High and Low Dose of L-Arginine Equally Ineffective in Promoting Nitric Oxide Synthesis in Young Active Men at Rest - GH and IGF-1 Response Negligible.

Image 1: Arginine based first generation
"nitric oxide booster", such as BSN's
NO-Xplode still have a huge fanbase

"No NO from l-arginine", you probably remember this or similar headlines from a few years ago, when the first studies seemed to indicate that l-arginine, the main "working" ingredient in all the (over-)hyped nitric oxide (NO) boosters that had become an integral part of the line-up of each and every major supplement producer was found not to increase the amount of nitric oxide in their consumers' bloodstream. Although these results stand in stark contrast to the early studies using intravenous infusion of l-arginine, which established the myth of the NO and growth hormone boosting effects of 2-amino-5-guanidinovaleric acid (l-arginine),  a 2007 study by Malinauskas et al. (Malinauskas. 2007) found that 8% of the male student athletes who participated in their survey were still interested in the ingestion of l-arginine containing supplements. Thus, it does not come as a surprise that - even with the rise of the so-called 2nd generation pre-workout products - the classic, l-arginine based products such as NO XPlode, SuperPump and Co. still have a huge fanbase, the majority of whose members, asked about why they are taking the respective product, will certainly answer "for the pump".

A very recent study by Scott C. Forbes and Gordon J. Bell , published in the Journal of Appl. Physiol. Nutr. Metab. (Forbes. 2011), is yet only the latest in series of investigations, which puts into question, how much of a placebo effect may be involved in the real-world observations of "enormous pumps and vasolidation" many consumers of l-arginine based preworkout products report. 14 weight training (4 sessions per week) male participants, who had been free from other nutritional supplements for at least 12 weeks participated in the study. In a double-blind repeated measure design with 3 testing conditions (baseline, placebo/l-arginine, l-arginine/placebo) that were separated by 7 days, the subjects received either high or low dose (0.075 (low) or 0.150g/kg (high)) l-arginine or placebo (flour) solved in 500ml of water after a 10 hour fast. Interestingly,

plasma concentrations significantly increased (p < 0.05) to a similar level [+178% and +204%] above resting values, respectively)at all time points in both the low- and high-dose conditions, while there was no change in the placebo condition over time.

Or, in other words, there was a tight regulation of maximal l-arginine levels in the plasma of the subjects, either via decreased absorption or increased metabolism of the orally ingested l-arginine (it is estimated that with increasing doses >40% of the ingested arginine is degraded by the small intestine). 

Apart from the issue of gastro-intestinal distress, simply increasing the dosage will thus not further increase the availability of arginine in the blood stream, which at the concentration that were observed in this study also failed to induce "a significant main effect for insulin (p < 0.05)". Previous studies using intravenously administered arginine had shown increased insulin secretion and, in some cases, onset hypoglycemia. In absence of these insulinogenic effects, however, there were also

no significant difference over time or between conditions for GH (Fig. 3), IGF-1 (Fig. 4), or glucose, (p > 0.05);

all that, despite the fact that the area under the curve (iAUC), a measure for the total amount of l-arginine that was taken up and metabolized by the subjects, did in fact reveal "a significant difference between the L-arginine conditions and placebo and between the high and low relative doses." With regard to the nitric oxide production, this dose dependent increase in plasma arginine levels turned out to be useless, or in fact counterproductive, as contrary to expectation the  area under the curve (iAUC) "for NOx with the high relative dose was significantly lower than that for the low dose of L-arginine" - a clear sign that "overuse" of large amounts l-arginine could diminishes the already negligible on nitric oxide production at rest.

Listen live to SHR tomorrow, Thursday @ 12:00PM ET

Before totally discarding arginine, however, I suggest you tune in to tomorrow's episode of Super Human Radio. In the 2nd installment of the "Amino Acids for Super Humans" series, I will provide further insights into what we really know about arginine and its "metabolic children" ornithine and citrulline and how they may effect how you look, feel and perform in and outside the gym.

Unexpected Performance Increments in Elite Wrestlers in Response to Well-Timed Arginine Supplementation: 5.8% Increased Time to Exhaustion, No Recution in O2 Cost!

Science is still wrestling with evidence in favor vs. against l-arginine

Actually the study at hand is not really exciting, the researchers from the Near East University Medical School in Cyprus recruited nine male national and international level wrestlers put them on more or less standardized diets, forbid them to work out and or use caffeine, stimulants or other ergogenic supplements and fed them 1.5g arginine per 10kg body weight (that's 12grams for someone with a body weight of 80kg).

Aside from the dosage, which would be on the higher side compared to the average arginine trial, there were no significant differences to study protocols you know.

Lear more about L-arginine at the SuppVersity!

No N.O. W/ Arginine

Arginine vs. High Lipids

Arginine Blunts GH?!

Arginine for Satiety?

Arginine vs. T2DM

Arginine for Fat Loss?

The subjects reported to the laboratory fasted in the AM, they have followed identical diets before both the active and the placebo trial and they had to perform one of those arduous pedal until you drop exercise tests on a cycle ergometer...

There was one difference, however. The subjects were not allowed to start working out immediately after they'd washed down the arginine / placebo supplement. Instead, they had to wait for sixty minutes for the arginine peak in plasma (Gannon. 2002).

Figure 1: Time to exhaustion and lactate levels increased, the VO2 costs of which you could expect that they decreased and would thus allow for the increased time to exhaustion, on the other hand, didn't change (Yavuz. 2014)

And voila! As you can see in Figure 1, Yavuz, Turnagol and Demirel observed a significant performance increase in the arginine trial.

In that, it is quite astonishing that these improvements occurred in the absence of changes in VO2 consumption. A reduction in O2 cost, as it was reported by Bailey et al. (2009) would after all be the most obvious explanation of the ergogenic effects of arginine.

Suggested Read: Arginine a BAT Building WAT Killer & Repartitioning Agent? Plus: The Arginine Enriched Biscuits Diet ;-) | read more

Bottom line: Previous results of studies with arginine supplementation on performance are rather inconsistent and it is difficult to say whether these differences can be explained by the length of the supplementation period, the combination of arginine with different components, different doses of arginine, different exercise protocols, different fitness levels of subjects (endurance trained athletes, physically active healthy men, or combat sports athletes as in the study at hand). Even the hitherto overlooked exact timing of supplementation and workout could make all the difference - so in case you still have a truckload of arginine lying around at home, remember to take it on an empty stomach and 60 minutes before your workouts.

Reference:

• Bailey, Stephen J., et al. "Dietary nitrate supplementation reduces the O2 cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans." Journal of Applied Physiology 107.4 (2009): 1144-1155.
• Gannon, Mary C., Jennifer A. Nuttall, and Frank Q. Nuttall. "Oral arginine does not stimulate an increase in insulin concentration but delays glucose disposal." The American journal of clinical nutrition 76.5 (2002): 1016-1022.
• Yavuz, H. U., H. Turnagol, and A. H. Demirel. "PRE-EXERCISE ARGININE SUPPLEMENTATION INCREASES TIME TO EXHAUSTION IN ELITE MALE WRESTLERS." Biol. Sport 31 (2014): 187-191.

8g+ (HED) of Arginine Boost Glucose Clearance & Triples GLP-1 Release in Lean and Obese Mice. Plus: 14+ Studies On Things Arginine Can Do For Diabetics & Athletes

Type II diabetes and insulin resistance has long become an issue for lean individuals as well. But can you really abuse your "pump supplement" as a means to stash away your post-workout carbs at a significantly increased pace?

Statements like "XY boosts" and figures like "+30%" are real attention-grabbers. I mean 200mg/dl glucose vs. 300mg/dl glucose after a 2g/kg glucose load that must certainly be significant, right? Well, as always, there are exceptions to the rule, but I can reassure you: it's not the case with the latest study from the College of Medicine at the University of Cincinnati (Clemmensen. 2013). How I know that? Well the I wrote about the real world significance of the increased glucose clearance, as well as the brown-adipose-tissue building and white adipose tissue burning effects of arginine, previously (see "Arginine: BAT Builder and WAT Killer" & "Arginine Enriched Biscuits for Diabetics"). Thus, the most recent revelation that the conditionally essential amino acid that's notorious for its non-existent effects on the pump is able to increase the GLP-1 response to a sugary meal and thus double the glucose clearance in lean mice only adds to what SuppVersity readers knew all along:

There is way more to arginine than "the pump"

Being aware that everybody believes to know exactly that the big bad insulin is the reason for the current obesity epidemic, I guess it's better to remind you that this is not just an unwarranted over-generalization, but completely beside the point. So I suggest you (re-)read "The "Pro-Insulinogenic" Effects of Non-Nutritive Sweeteners + Mechanisms & Consequences" (just do it!), if you feel like running away, when you take a closer look at the right hand side of figure 1:

Figure 1: AUC under the glucose curve (left), actual glucose response after oral glucose tolerance test 15min after the ingestion of arginine in lean and obese mice (middle) and insulin response to arginine and subsequent ingestion of dextrose during the OGGT (right; Clemmensen. 2013)

What you are seeing here is an insulin SPIKE that deserves to be written in capital letters, but the way it ameliorates the surge in blood glucose in the diet-induced obese (~type II diabetic) mice could actually protect the rodents from developing many of the neurological and endocrine side effects of high blood glucose levels and not insulin, which has only recently been demonstrated to ameliorate the cognitive decline in dementia and Alzheimer's (Craft. 2012).

I know you are not dietary obese

Figure 2: GLP-1 response in the lean mice in the study at hand (foreground, top-right; Clemmensen. 2013) and selected effects of GLP-1 (background; from byettahcp.com)

Now, while the data on the right hand side of figure 1 may be relevant for your obese neighbor,  we are actually more interested in the data on the left, which does, by the way, make it quite clear that the problem with being obese is not an increase in insulin release, but the mere fact that even that is not going to help you clear the sugar out of the blood stream.

Compared to the obese mice, where we see a slight, but at 60min significant improvement in glucose clearance, the lean mice did not even give the 2g/kg body weight of glucose they received a chance to accumulate in their blood. Rather than that, they cleared it almost instantly.

The researchers hypothesis that this effect was mediated by the concomitant up to 3x increase in GLP-1 production was supported by a follow up experiment using a genetically modified strain of mice that lacks the GLP-1 receptor, in whom the corresponding improvements in blood glucose management were absent. In the discussion of their results, the researchers add:

Suggested read: "Glycemic Load, the GI's Complex Brother, Turns Out to Be A Good Predictor of Postprandial GLP-1 and GIP Response" | read more

"The GLP-1 incretin effect has traditionally been ascribed to effects on intestinal L cells elicited by ingested carbohydrate, but the findings reported here support the involvement of gut hormones to link protein ingestion with insulin secretion.

This has also been recently suggested in studies of humans consuming meals of specific macronutrient composition (Carrel. 2011).

Also, we have recently reported that long-term dietary supplementation with L-arginine improves glucose metabolism in mice exposed to a low-protein diet (Clemmensen. 2012)." (Clemmensen. 2013)

Despite the fact that GLP-1 analogues have been used with quite some success in the treatment of type II diabetes in the recent years, our understanding of the far-reaching effects of this "satiety hormone" is still far from being comprehensive (suggested read: "Eat More, Burn More and Lose Fat Like on Crack w/ GLP-1"). What we do know is that it occupies a central position in the control of our energy intake, though. And I am pretty sure is not the SuppVersity post about glucagon-like peptide 1 (GLP-1), you are about to read.

---

But does that even work for you? For (pre-)diabetics we can rely on data from Piatti et al. (2001) who found a 34% increase in insulin clearance after one months on 3g/day l-arginine and data from Lucotti (2006) who observed that the addition of 8.3g of l-arginine to a hypocaloric diet + exercise regimen boosted the loss of fat mass and and waist circumference while increasing the lean mass retention and improving daily glucose and fructosamine profiles, significantly. For the sick / obese we do also have human (H) and rodent studies (R) supporting

• 

  Whenever the word "vascularity" appears on one of the boards, this image pops up. Now we know that arginine alone won't make your veins pop, but could it be that we have hitherto overlooked that it could help you meet another more important criteria to look like that - namely to drop body fat? Learn more in a previous SuppVersity article on arginine's BAT building and WAT killing effects and it's use as a repartitioning Agent (read more)

  an anti-platelet effect of 8.4g arginine per day in hypercholesterolemic humans (Wolf. 1997; H)
• indirect anti-oxidant effects of 2x3g arginine per day in in diabetic patients with atherosclerotic peripheral arterial disease of lower extremities (Jablecka. 2012; H)
• an ameliorative effect on diabetes induced gastrointestinal malfunction (Míguez. 2004; R)
• improved wound healing when administered alone (Witte. 2002; R) or with proline (Raynaud-Simon. 2012; R)
• significantly reduced body fat mass in rodent model of diet induced diabesity (Fu. 2005; R)
• beneficial effects on the hypertensive offspring of diabetic dams (Cavanal. 2007; R) 
• direct mechanistic effects that inhibit the storage of fat in white adipose tissue (Tan. 2012; R + H + PIG)
• reductions in diabetes induced bone loss (Pennisi. 2009; R)
• amelioration of the negative effects on insulin sensitivity in response to a low (no typo!) salt diet (Ruivo. 2006; R)

The benefits for lean individuals are not that clear, studies like Gater et al. (1992), for example, tested the effect of the purportedly GH boosting combination of arginine + lysine and saw no effects in their healthy young participants. Other studies did however find ...

• 

  Suggested read: "Post-Workout Glycogen Repletion - The Role of Protein, Leucine, Phenylalanine and Insulin." | read more

  a reduced oxidation of glucose when well-trained cyclists used a mixture of 1 g carbohydrate/kg body mass and 0.08 g arginine-hydrochloride/kg body weight to refuel their muscle glycogen after a workout (Yaspelkis. 1999)
• significantly lowered blood pressure and improved renal function and carbohydrate metabolism in healthy volunteers (Siani. 2000)
• significantly increased rates of glucose disposal during exercise in trained cyclists (McConell. 2006; Linden. 2011)
• direct beneficial effects on glucose and fatty acid metabolism in muscle cells (de Castro Barbosa. 2013)
• reduced blood lactate accumulation & oxygen consumption during submax. exercise after prolonged intake of L-arginine-L-aspartate (Burtscher. 2005)

So, if it there was not the likely possibility that many of these benefits occur only with a low(ish) protein intake,  I would say: Arginine can do a lot of interesting things for you. With a possible beneficial effect on post-workout glycogen repletion being what I consider most significant for the lean physical culturist. There is yet one thing arginine cannot do and that's worth remembering, because it tells you something about the supplement business: It won't increase the pump.


References:

• Burtscher M, Brunner F, Faulhaber M, Hotter B, Likar R. The prolonged intake of L-arginine-L-aspartate reduces blood lactate accumulation and oxygen consumption during submaximal exercise. J Sports Sci Med. 2005; 4(3), 314-322.
• Carrel G, Egli L, Tran C, et al.Contributions of fat and protein to the incretin effect of a mixed meal. Am J Clin Nutr. 2011;94(4):997–1003. 
• Cavanal Mde F, Gomes GN, Forti AL, Rocha SO, Franco Mdo C, Fortes ZB, Gil FZ. The influence of L-arginine on blood pressure, vascular nitric oxide and renal morphometry in the offspring from diabetic mothers. Pediatr Res. 2007 Aug;62(2):145-50.
• Clemmensen C, Madsen AN, Smajilovic S, Holst B, Bräuner-Osborne H.L-Arginine improves multiple physiological parameters in mice exposed to diet-induced metabolic disturbances.Amino Acids. 2012;43(3):1265–1275.
• Clemmensen C, Smajilovic S, Smith EP, Woods SC, Bräuner-Osborne H, Seeley RJ, D’Alessio DA, Ryan KK. Oral L-Arginine Stimulates GLP-1 Secretion to Improve Glucose Tolerance in Male Mice. Endocrinology. First published ahead of print August 19, 2013.
• Craft S, Baker LD, Montine TJ, Minoshima S, Watson GS, Claxton A, Arbuckle M, Callaghan M, Tsai E, Plymate SR, Green PS, Leverenz J, Cross D, Gerton B. Intranasal insulin therapy for Alzheimer disease and amnestic mild cognitive impairment: a pilot clinical trial. Arch Neurol. 2012 Jan;69(1):29-38.
• de Castro Barbosa T, Jiang LQ, Zierath JR, Nunes MT. L-Arginine enhances glucose and lipid metabolism in rat L6 myotubes via the NO/ c-GMP pathway. Metabolism. 2013 Jan;62(1):79-89.
• Fu WJ, Haynes TE, Kohli R, Hu J, Shi W, Spencer TE, Carroll RJ, Meininger CJ, Wu G. Dietary L-arginine supplementation reduces fat mass in Zucker diabetic fatty rats. J Nutr. 2005 Apr;135(4):714-21.
• Gater DR, Gater DA, Uribe JM, Bunt JC. Effects of arginine/lysine supplementation and resistance training on glucose tolerance. J Appl Physiol. 1992 Apr;72(4):1279-84.
• Jabłecka A, Bogdański P, Balcer N, Cieślewicz A, Skołuda A, Musialik K. The effect of oral L-arginine supplementation on fasting glucose, HbA1c, nitric oxide and total antioxidant status in diabetic patients with atherosclerotic peripheral arterial disease of lower extremities. Eur Rev Med Pharmacol Sci. 2012 Mar;16(3):342-50.
• Linden KC, Wadley GD, Garnham AP, McConell GK. Effect of l-arginine infusion on glucose disposal during exercise in humans. Med Sci Sports Exerc. 2011 Sep;43(9):1626-34.
• Lucotti P, Setola E, Monti LD, Galluccio E, Costa S, Sandoli EP, Fermo I, Rabaiotti G, Gatti R, Piatti P. Beneficial effects of a long-term oral L-arginine treatment added to a hypocaloric diet and exercise training program in obese, insulin-resistant type 2 diabetic patients. Am J Physiol Endocrinol Metab. 2006 Nov;291(5):E906-12. 
• McConell GK, Huynh NN, Lee-Young RS, Canny BJ, Wadley GD. L-Arginine infusion increases glucose clearance during prolonged exercise in humans. Am J Physiol Endocrinol Metab. 2006 Jan;290(1):E60-E66.
• Míguez I, Mariño G, Rodríguez B, Taboada C. Effects of dietary L-arginine supplementation on serum lipids and intestinal enzyme activities in diabetic rats. J Physiol Biochem. 2004 Mar;60(1):31-7.
• Pennisi P, Clementi G, Prato A, Luca T, Martinez G, Mangiafico RA, Pulvirenti I, Muratore F, Fiore CE. L-arginine supplementation normalizes bone turnover and preserves bone mass in streptozotocin-induced diabetic rats. J Endocrinol Invest. 2009 Jun;32(6):546-51.
• Piatti PM, Monti LD, Valsecchi G, Magni F, Setola E, Marchesi F, Galli-Kienle M, Pozza G, Alberti KG. Long-term oral L-arginine administration improves peripheral and hepatic insulin sensitivity in type 2 diabetic patients. Diabetes Care. 2001 May;24(5):875-80. 
• Raynaud-Simon A, Belabed L, Le Naour G, Marc J, Capron F, Cynober L, Darquy S. Arginine plus proline supplementation elicits metabolic adaptation that favors wound healing in diabetic rats. Am J Physiol Regul Integr Comp Physiol. 2012 Nov 15;303(10):R1053-61.
• Siani A, Pagano E, Iacone R, Iacoviello L, Scopacasa F, Strazzullo P. Blood pressure and metabolic changes during dietary L-arginine supplementation in humans. Am J Hypertens. 2000 May;13(5 Pt 1):547-51. 
• Tan B, Li X, Yin Y, Wu Z, Liu C, Tekwe CD, Wu G. Regulatory roles for L-arginine in reducing white adipose tissue. Front Biosci (Landmark Ed). 2012 Jun 1;17:2237-46. Review.
• Witte MB, Thornton FJ, Tantry U, Barbul A. L-Arginine supplementation enhances diabetic wound healing: involvement of the nitric oxide synthase and arginase pathways. Metabolism. 2002 Oct;51(10):1269-73.
• Wolf A, Zalpour C, Theilmeier G, Wang BY, Ma A, Anderson B, Tsao PS, Cooke JP. Dietary L-arginine supplementation normalizes platelet aggregation in hypercholesterolemic humans. J Am Coll Cardiol. 1997 Mar 1;29(3):479-85.
• Yaspelkis BB 3rd, Ivy JL. The effect of a carbohydrate--arginine supplement on postexercise carbohydrate metabolism. Int J Sport Nutr. 1999 Sep;9(3):241-50.

Arginine a BAT Building WAT Killer & Repartitioning Agent? Plus: The Arginine Enriched Biscuits Diet ;-)

Whenever the word "vascularity" appears on one of the boards, this image pops up. Now we know that arginine alone won't make your veins pop, but could it be that we have hitherto overlooked that it could help you meet another more important criteria to look like that - namely to drop body fat?

In a 2012 paper Mohammad Alizadeh and his colleagues published a paper in the Annals of Nutrition & Metbabolism. The paper deals with the effects of the addition of 5g/day l-arginine to hypocaloric diets in a group of 84 premenopausal women, where the supplement regimen led to significantly greater reductions in visceral obesity (8cm vs. just 4cm reduction in waist circumference within 6 weeks; cf. Alizadeh. 2012). I filed the paper in my "candidates" folder and forgot about it - simply too much interesting news to cover everything.

Now, almost a year later, Lucilla D. Monti et al. have published yet another paper on l-arginine in the latest issue of the scientific journal Metabolism (Monti. 2013). "A pilot study in healthy subjects and a cross-over study in subjects with impaired glucose tolerance and metabolic syndrome" as the title tells us and reason enough for me to take another look at an amino acid that has gotten sort of a bad rep as a supplemental non-starter, because the marketing machinery of the bodybuilding supplement producer has been pimping it as an "nitric oxide (NO) booster" (which is similar to saying that bricks were 'house builders' by the way).

Arginine cookies the saviors of the human race!?

Just so there is no misunderstanding here, while arginine may be more useful as a weight loss tool (esp. for the insulin resistant), it is neither an NO booster, nor a fat burner in the sense that it would "actively" do anything to elicit the named effects. The additional 4cm the arginine stripped off the waists of the initially mentioned ~28-44year-old women, for example, occurred in the context of a diet containing 500kcal less than the baseline diet (that's about -20% and the average subject ended up eating ~2000kcal/day).

Figure 1: As this illustration goes to show you, nitric oxide (NO) play and important role in the activation of PPAR-alpha and will thus determine (among other factors) if your immature fat cells become ugly passive and potentially health threatening stores or metabolically active brown adipose tissue (based on Wu. 2012).

Nevertheless, it is unquestionably interesting that Zhenlong Wu et al. remark in one of the more recent reviews on the fat loss effects of l-arginine that the inconspicuous nitric oxide precursor has the hardly known ability to

"increases mammalian BAT growth and development via mechanisms involving gene expression, nitric oxide signaling, and protein synthesis [, so that t]his enhances the oxidation of energy substrates and, thus, reduces white fat accretion in the body." (Wu. 2012)

Usually I would discard these effects as "most likely irrelevant for virtually BAT free mammals" like humans (even those among us with a "high" amount of brown adipose tissue have way less of it than the average "mammal" does; this is particularly true if you compare us to our small hairy mammalian brethren that are living in lab cages ;-).

With the positive effects that have already been observed in past human studies and the "growth promoting effect" arginine is supposed to have on mammalian brown adipose tissue (cf. figure 1), the potential weight loss and ensuing health benefits of the "conditionally essential" (meaning you must consume it in significant amounts under certain circumstances, like bein very sick, burned, hurt, etc. though your body can theoretically produce it on its own) amino acid appear to be well-worth being mentioned in a SuppVersity article again (again, because I already mentioned these effects as an aside in Part II of the Amino Acids for Super Humans Series back in 2011.

Back to the cookies then

After this lengthy general introduction, let's now finally have a look at the Monti study (Monti. 2013). Now, despite the auspicious term "pilot study" in the title of the Italian researcher latest paper, the idea to add some l-arginine to cookies, biscuits and other stuff is actually not really new. In 2011, already, he same research group has published a paper on this concept with initial data on the acute response to the ingestion of arginine enriched biscuits (see previous SuppVersity post). So, the "pilot trial" is actually nothing but a slightly revamped version of the initial test in 7 healthy subjects, plus a 2-week extension in which the scientists probed the effects of the chronic ingestion of their biscuits on 15 obese subjects (8 men, 7 women, aged 62.5±3.5years; BMI ~30kg/m²; 36% body fat) with impaired glucose tolerance (IGT) and metabolic syndrome (MS).

Figure 2: Weight loss, fat loss and insulin sensitivity (*I divided the actual values on the Matsuda index by 10 so that they would fit into the same graph), as well as glucose response during an OGGT (Monti. 2013)

While the results of the former trial were very similar to those in the pilot of the pilot study (see previous SuppVersity post), the data in figure 1 goes to show you that the "long-term" (14-days, with a wash out period of another 14 days and a cross-over afterwards, so that every subject was tested both for the effects of the placebo and the acuve treatment), were promising and statistically significant, but far from representing a solution to the diabesity epidemic.

During each of the two 14-day intervention periods, the obese volunteers had consumed identically packaged L-arginine-enriched biscuits containing 6.6g l-arginine, 21.9g carbohydrates (15g available
carbohydrates and 6.9g resistant starch), 3.6g protein, 7.5g fat or an isoenergetic biscuit without the 6.6g of l-arginine as morning and afternoon snack . The additional 171kcal provided by the biscuits were included in the daily allowance of the subjects who followed a 55% carbohydrate, 25%–30% fat and 15%–20% protein diet that contained a total of 1,600kcal during the whole 6-week study period (the study used a randomized cross over design with a 2-week washout in-between).

Let's get back to a more general perspective

Not just because I'd hope that most of you don't have just as much weight to lose as the participants of the Monti study, but also in view of statements like "[a]nother added value of the biscuit is the low protein content (6.1% vs. 20%–50%)" (Monti. 2013) in the discussion of the paper, I don't want to go into more details on this particular study, but rather return to a more general analysis of the metabolic effects of l-arginine in these last paragraphs. I mean, it should be obvious that the important most important question here is: "Is there any metabolic benefit of arginine supplementation, or not?

The results of the Monti study clearly show that there is (and that despite the fact that its authors' don't appear to have a grasp of the latest research results). Monti's paper does yet not describe the only experiment, the results of which would suggest that there is more to arginine than nitric oxide - or, if we go by the overview in figure 1, that there is more to nitric oxide than the pump.

• In June 2012, researchers from the Poznan University of Medical Sciences in Poland, for example, published a paper in which they report that the provision of 9g/day of the nitric oxide precursor l-arginine for 3-months lead to statistically highly significant improvements in insulin sensitivity and a non-significant 1% reduction in body fat in the absence of any changes in dietary or activity patterns in patients with visceral obesity (BMI 39kg/m²). It did yet not, as the scientists had speculated reduce the expression of tumor necrosis factor alpha (TNF-alpha), so that we have to assume that the beneficial effects on glucose management were not mediated by any hitherto largely ignored direct anti-inflammatory effects of the amino acid the Swiss chemist Ernst Schultze discovered in 1886 (Bogdanski. 2012). 
• In the American Journal of Physiology. Endocrinology and Metabolism Lucotti et al. reported in 2006 that the addition of l-arginine (8.3g/day) to a combined diet plus exercise program for 21 days had highly beneficial effects on the study outcome, promoted the loss in fat mass (3kg vs. 2kg) and waist circumference (10cm vs. 3cm; no typo!), helped preserve lean mass (0kg vs. 2kg muscle loss) and improved the mean daily glucose profiles and the amount of fructosamine, a glycated serum protein and marker of poor glucose control, in the blood (Lucotti. 2006). Moreover, the supplementaion protocol increased the nitric oxide production, the andioxidant capacity and the adiponectin levels and improved the adiponectin-to-leptin ratio of the 25 women and 8 men (all obese, BMI ~39kg/m²) who participated in the study. 
• In addition, studies on rodents and pigs have conclusively shown that arginine supplementation can increase the use and decrease the storage of fatty acids in different dietary scenarios (Fu. 2005; Jobgen. 2009; Tan. 2011).

One thing we should not forget, though is that there may in fact be something like an "arginine timing" effect, which could play a role in it's effect on body composition. In the scientific journal Amino Acids Smajilovic et al. report only recently that the l-arginine induced release of insulin is not mediated by a direct interaction of the alpha-amino acid with the amino acid receptors on the pancreas. Now, despite the fact that we do not know how, the mere fact that arginine will produce an immediate release of insulin tells us that it's use before / with a meal, would be more beneficial than during periods of fasting. This is particularly true for people who are either developing or at risk of developing insulin resistance and type II diabetes. After all, the decline in the early insulin response to the meal has been implicated as one of the first and most important steps in the etiology of type II diabetes (Pratley. 2001; Del Prato. 2002).

Is timing crucial and what about the arginine induced insulin release?

Maybe it's even it's effect on the health of your intestines (read more about that) that helps weight loss, who knows?

Unfortunately, few studies report whether the arginine was ingested before or with a meal. What we do know from the Monti study, however,  is that it's presence in the meal (which would be equal to the co-ingestion of supplemental l-arginine) tripled the amount of body fat the dieting subjects lost in the course of the two week intervention (2.02kg vs. 0.70kg). In conjunction with the previously mentioned ability to boos pancreatic insulin production, this observation would invalidate the still widely heralded assumption that a robust, appropriate early insulin response (critics would call it a "spike") would be something to be avoided at all costs - if it were, the l-arginine should have decreased the efficacy of the diet, right?

What we should however keep in mind, though is that a robust initial insulin response will lead to a faster reduction of blood glucose in into the normal range. That it turn will (ideally) render the release of even more insulin obsolete so that the initial spike will actually allow you to avoid the far more detrimental chronically (or in a "healthy" individual "long-term") elevation of insulin and can thus have the bring about the exact opposite of what most people believe it will do: weight loss, or a reduction in weight gain!

"So does it work and if so how? Can't be insulin, alone, can it?"

It is nevertheless unlikely that the increased acute response of the pancreas is the only mechanism (I would bet probably not even the most important one) by which increases in the amount of arginine in the diet facilitate and as examples like the study by Bogdanski et al. (Bogdanski. 2012) even trigger weight loss (remember: the obese subjects in this study did not do anything but take 9g/day of supplemental l-arginine three times a day).

Effects by which arginine could promote fat loss and body recompositioning: Stimulation of lypolysis (release fat from adipose tissue); activation of genes that are responsible for the oxidation of fatty acids; interaction with PGC-1 alpha and triggers mitochondrial biogenesis and the "browning" of fat; regulation of adipocyte-muscle crosstalk resulting in an energy repartitioning effect away from the adipose and towards the muscle tissue; activation of the AMPK pathway, resulting in improvements in both lipid and glucose metabolism.

According to a review by Tan et al., both the additive (dieting + arginine = better fat loss), as well as the "stand alone" (simply adding arginine on top of whatever diet you are following) effects of the nitric oxide precursor could be brought about by a combination of various factors (Tan. 2012). We have already seen in figure one that the nitric oxide exerts direct agonistic effects on PPAR-alpha. We also know that other substances such as fish oil and TTA (see "TTA + Fish Oil - Fat Burning Super Fats?"), which are likewise PPAR-alpha agonists will also promote the oxidation of fatty acids (specifically in the liver). Now, if you add the list of metabolic benefits, the scientists from the Institute of Subtropical Agriculture at the Chinese Academy of Sciences in Changsha and their colleagues from the Texas A&M University have compiled (see infobox on the right), you will have to concede that your pre-workout nitric oxide booster would - at least on paper - make a pretty decent "fat burner", if all these effects, most of which have been observed in either rodents or pigs could be replicated in human beings.

Bottom line: For the metabolically deranged, the evidence is there. For followers of physical culture, on the other hand, there is as of yet no clear cut proof for the fat burning or repartitioning effects of l-arginine. Ah, and just in case you consider your little N=1 experiment with whatever pre-workout supplement evidence that it does not work - forget about that. With the minuscule amounts of l-arginine most of these products contain you can hardly make a difference when your basal diet does deliver tons of arginine, already (plus: you were probably taking it at the wrong time, namely on empty before a workout).

So do I suggest you buy a 5kg pouch of bulk l-arginine and go through it within 2 weeks? No, certainly not. You better wait until more data becomes available. For now, it would suffice if you don't fall for the anti-hype that's at least in part instigated by the same supplement companies that have been pimping l-arginine a couple of years ago as the ueber-supplement and an absolute must have for any serious trainee. I mean if you had the choice between six pack abs lasting 24/7 and a pump, what would you pick? I thought so... therefore this new area of application, could turn out to be way more exciting than the never-established, but highly marketed NO-boosting effects of l-arginine.

References:

• Alizadeh M, Safaeiyan A, Ostadrahimi A, Estakhri R, Daneghian S, Ghaffari A, Gargari BP. Effect of L-arginine and selenium added to a hypocaloric diet enriched with legumes on cardiovascular disease risk factors in women with central obesity: a randomized, double-blind, placebo-controlled trial. Ann Nutr Metab. 2012;60(2):157-68.
• Bogdanski P, Suliburska J, Grabanska K, Musialik K, Cieslewicz A, Skoluda A, Jablecka A. Effect of 3-month L-arginine supplementation on insulin resistance and tumor necrosis factor activity in patients with visceral obesity. Eur Rev Med Pharmacol Sci. 2012 Jun;16(6):816-23.
• Del Prato S, Marchetti P, Bonadonna RC. Phasic insulin release and metabolic regulation in type 2 diabetes. Diabetes. 2002 Feb;51 Suppl 1:S109-16.
• Fu WJ, Haynes TE, Kohli R, Hu J, Shi W, Spencer TE, Carroll RJ, Meininger CJ, Wu G. Dietary L-arginine supplementation reduces fat mass in Zucker diabetic fatty rats. J Nutr. 2005 Apr;135(4):714-21.
• Jobgen W, Fu WJ, Gao H, Li P, Meininger CJ, Smith SB, Spencer TE, Wu G. High fat feeding and dietary L-arginine supplementation differentially regulate gene expression in rat white adipose tissue. Amino Acids. 2009 May;37(1):187-98.
• Lucotti P, Setola E, Monti LD, Galluccio E, Costa S, Sandoli EP, Fermo I, Rabaiotti G, Gatti R, Piatti P. Beneficial effects of a long-term oral L-arginine treatment added to a hypocaloric diet and exercise training program in obese, insulin-resistant type 2 diabetic patients. Am J Physiol Endocrinol Metab. 2006 Nov;291(5):E906-12.
• Monti LD, Casiraghi MC, Setola E, Galluccio E, Pagani MA, Quaglia L, Bosi E, Piatti P. l-Arginine enriched biscuits improve endothelial function and glucose metabolism: A pilot study in healthy subjects and a cross-over study in subjects with impaired glucose tolerance and metabolic syndrome. Metabolism. 2013; 62:255–26.
• Pratley RE, Weyer C. The role of impaired early insulin secretion in the pathogenesis of Type II diabetes mellitus. Diabetologia. 2001 Aug;44(8):929-45.
• Tan B, Yin Y, Liu Z, Tang W, Xu H, Kong X, Li X, Yao K, Gu W, Smith SB, Wu G. Dietary L-arginine supplementation differentially regulates expression of lipid-metabolic genes in porcine adipose tissue and skeletal muscle. J Nutr Biochem. 2011 May;22(5):441-5.
• Tan B, Li X, Yin Y, Wu Z, Liu C, Tekwe CD, Wu G. Regulatory roles for L-arginine in reducing white adipose tissue. Front Biosci. 2012 Jun 1;17:2237-46.

Arginine Blunts Growth Hormone Response to Resistance Training: Will the -41% Reduction in Post-Workout Growth Hormone Release Hamper Your Strength & Size Gains?

Arginine-based pre-workout products are more popular with guys than with girls. Could this be the reason that only women complain about unlovedly rapid muscle gains? ;-)

No, this is not a typo! The verb in the headline of today's SuppVersity article really is "to blunt", as in "to neutralize partially" (OED Online 2013). I have to admit that I was also surprised, when I spotted the study over in the "ahead of print" section of the International Journal of Sports Nutrition and Exercise Metabolism. Unless Forbes, Harber and Bell, of whom you will learn later that they've already conducted another 'arginine study', messed up, the results of their most recent experiment do yet leave little doubt: Arginine, an amino acid that is used to test the function of the GH-releasing somatotropic cells within the lateral wings of the anterior pituitary, does - when it is administered at a dosage of 0.075 g·kg-1 body mass right before an acute bout of resistance exercise (3 sets of 8 exercises, 10 repetitions at ~75% 1RM) attenuate the post-workout growth hormone surge in strength trained individuals (Forbes. Nov 2013).

You want more details? Here you go...

With ~5-6g of arginine being taken before a workout that consists of 3 sets of 8 classic strength training exercises that are performed for 10 repetitions and at an intensity ~75% of the personal 1RM of the 14 strength trained men [age: 25±4 y; body mass: 81.4±9.0 kg; height: 179.4±6.9 cm; and training experience: 6.3±3.4 y], the researchers from the Faculty of Physical Education & Recreation at the University of Alberta in Edmonton, Alberta, Canada designed an experimental setup which comes "shockingly" close to what the average and extraordinaire gymrat is doing, when he or she is hitting the grind.

Figure 1: Level of arginine, GHRH and IGF-1 at T = 0, 15, 30, 60 min of rest-recovery + integrated area under the curve for growth hormone (iAUC GH); all values expressed relative to placebo control (Forbes. Nov 2013)

Against that background the question whether you and the rest of the millions of hobby athletes who spend hundreds of bucks on pre-workout products every year have been hampering their own progress is, as hilarious as it may sound, not a totally unwarranted one. I mean, we can hardly ignore the statistically highly significant -41% reduction in total growth hormone secretion in the one hour "anabolic window" after the workout, Forbes and his colleagues measured - can we?

What do we make of these results?

Most of you will probably remember the often referenced results of West & Phillips, whose 12-week resistance training intervention in the course of which the researchers from the Exercise Metabolism Research Group at the Department of Kinesiology of the McMaster University in Hamilton, Ontario,  made the following observations (West. 2012):

• 

  Suggested Read: "Anabolic Workouts Revisited!" | more

  No correlations between GH, testosterone or IGF-1 and the lean mass gains of their 56 recreationally active young men, who were not actively participating in any weightlifting
  activities <8 months before the study.
• Significant correlations between GH and the increase in type I (slow twitch, oxidative) muscle fibers, but no correlation between testosterone, IGF-1 and cortisol.
• Significant correlations between GH, as well as cortisol and the increase in type II (fast twitch, gylcolytic) muscle fibers, but no correlation between testosterone and IGF-1.

Unlike Forbes, Harber and Bell in the study at hand, West and Phillips measured the hormone levels for up to 2h after the workout. It is thus possible, but in view of the progression of the GH levels in the Forbes study relatively unlikely, that we'd see a rapid increase in the 2nd hour of the rest period and thus an increase in the total amount of GH that's released in response to the combination protocol (arginine + exercise).

Is the decrease the result of a previous GH "overload"?

With respect to the possible involvement of an auto-negative feedback, which is another, previously suggested explanation for this phenomenon, of which I had to realize during my research for this article that it has been covered in the literature before (Kanalay. 2008), Forbes et al. remark that their data would basically exclude the possibility that "the GH suppression was not due to a GH or IGF-1 induced autonegative feedback loop." (Forbes. Nov 2013)

It may not be the perfect muscle builder and maybe not even something you want to take in the vicinity of a workout, but there is still promising data on the metabolic effects of arginine esp. for (pre-)diabetics | more

In other words, Forbes et al. exclude the possibility that the subjects experienced a rapid increase in growth hormone as we would see it in response to the intravenous injection of arginine (10x increase with 20g/m² surface area of the 12 normal men in a 1996 study by Rahim et al.) that would then have shut down the GH production just as the exogenous administration of steroids would shut down your natural testosterone production.

If we focus on the available data, the conclusion of the researchers from the University of Alberta is certainly right. If we do take into account that we are talking about post workout supplementation and remind outselves that "the somatotrope is also known to have a refractory period" (Kanaley. 2008), it should be obvious that post-workout measurements, alone, cannot exclude the possibility that the GH spike that's responsible for the auto-negative feedback occurred during, not after the workout.

In other words: Instead of focusing exclusively on the post-workout GH levels, Forbes, Harber and Bell would actually have had to measure the pre & intra-workout GH response, as well. The GH spike that would cause the auto-negative feedback could after all have been caused by a sudden drop in blood glucose in response to the insulin sensitizing effects of arginine and the 'glucose hungry' strength training session.

Auto-negative feedback is still possible, but isn't there something else?

An alternative explanation for the lowered growth hormone response may come from a closer reading of the 'prequel' to this study. In January, Forbes et al. published a paper with the same supplement, but a different exercise protocol. Instead of hitting the weights, their 15 aerobically trained male subjects cycled for 60 min at 80% of their personal VO2_max - again, immediately after ingesting 5-6g of l-arginine (0.075g/kg body weight).

Is there anything arginine is good for, if it's not a muscle builder and it's effects on nitric oxide are overblown? There is a previous SuppVersity article that would suggest so: "Arginine a BAT Building WAT Killer & Repartitioning Agent?" | more

Contrary to the strength training routine, the (relatively) high intensity cycling had identical effects on the hormonal, metabolic and cardio-respiratory markers of the subjects, the two things that differed, though, were

• the rate of fatty acid oxidation at the onset of the workout, which was reduced in the l-arginine group, and
• the levels of the sugar alcohol glycerol at the 45-min time point, which were slightly, but significantly increased

These observations stand in line with the effects McConell et al.  observed in a 2006 study in response to the infusion of l-arginine.

The arginine infusion increased the glucose uptake and blunted the increase in nonesterified fatty acid and glycerol concentrations during 120min of cycling at 72% of the VO2max which were followed immediately by a 15-min "all-out" cycling performance bout (McConell. 2013). Whether it also changed the GH response is however something I can't tell you, because reseachers from the The University of Melbourne did not measure the effect the arginine infusion had on the growth hormone levels of their study participants. I would yet guess that it will have been similar to the one on the cycling study Forbes did. This, in turn, would suggest that the effect depends on (a) duration and energy expenditure, or (b) the substrate utilization during the workout (lifting weights = glycolytic; cycling = rather oxidative). In the end both of these are related to the reliance on fat, not glucose / glycogen to fuel the energetic demands of your workout and as you all know the acute provision of  glucose is the prerogative of glucocorticoids (i.e. cortisol), not GH.

There may be another reason arginine does not make you "big": It's one out of three amino acids that have an especially pronounced satiety effect | learn about the others!

I can't exactly tell you why, but I can tell you that... I openly admit that I was surprised by the results of the study at hand. I  surprised that I missed this (side) effect of arginine, before, but I am not worried that the arginine supplements you may be or may have been taking are / were  hampering your training success.

 If that was the case one of the many "real-world" arginine supplementation studies, where the study outcome wasn't some funky hormonal marker of which we still don't know whether / to which extent it actually affects skeletal muscle hypertrophy, would have shown a trend for decreasing performance, lean mass and strength gains with arginine supplementation - this, I can assure you was not the case.

In fact, those of you who remember one of my posts on the 'arginine powered' VPX preworkout products (learn more), will remember that the scientists observed, if anything, opposing, i.e. beneficial effects from complex preworkout products as most of you will be using. A somewhat different picture emerges for the 'arginine only studies' where "only" three out of five acute supplementation and four out of eight chronic supplementation studies showed measurable, but in many cases negligible performance gains (Alvares. 2011). And the null-effect the authors of the other papers observed is no reason to be concerned, either.

References:

• Álvares TS, Meirelles CM, Bhambhani YN, Paschoalin VM, Gomes PS. L-Arginine as a potential ergogenic aid in healthy subjects. Sports Med. 2011 Mar 1;41(3):233-48.
• "blunt, v.". OED Online. September 2013. Oxford University Press. http://www.oed.com/view/Entry/20664?rskey=iZQVcA&result=3&isAdvanced=false (accessed November 19, 2013).
• Forbes SC, Harber V, Bell GJ. The acute effects of L-arginine on hormonal and metabolic responses during submaximal exercise in trained cyclists. Int J Sport Nutr Exerc Metab. 2013 Aug;23(4):369-77. Epub 2013 Jan 8.
• Forbes SC, Harber V, Bell GJ. Oral L-Arginine Prior To Resistance Exercise Blunts Growth Hormone in Strength Trained Males. Int J Sport Nutr Exerc Metab. 2013 Nov 13. [Epub ahead of print]
• Kanaley JA. Growth hormone, arginine and exercise. Curr Opin Clin Nutr Metab Care. 2008 Jan;11(1):50-4. Review.
• McConell GK, Huynh NN, Lee-Young RS, Canny BJ, Wadley GD. L-Arginine infusion increases glucose clearance during prolonged exercise in humans. Am J Physiol Endocrinol Metab. 2006
• Rahim A, Toogood AA, Shalet SM. The assessment of growth hormone status in normal young adult males using a variety of provocative agents. Clin Endocrinol (Oxf). 1996 Nov;45(5):557-62.
• West DW, Phillips SM. Associations of exercise-induced hormone profiles and gains in strength and hypertrophy in a large cohort after weight training. Eur J Appl Physiol. 2012 Jul;112(7):2693-702.

L-Arginine - 6g/Day Boost Cholesterol- & Non-Esterified Fatty Acid Lowering Effects of Resistance Training. Are Classic Pre-Workouts Actually "Health Supplements"?

Lifting will improve your blood lipids, l-arginine will boost the effect.

In the spirit of Tuesday's post on the potential negative effects of nitrate supplements on weight loss (learn more + see box below for some important clarifications), I would like to invite you to take a look at the effects of "short-term  L-arginine  supplementation  on  lipid  profile  and  inflammatory proteins after acute resistance exercise in overweight men" as they are about to be reported in one of the future issues of e-SPEN, the European e-Journal of Clinical Nutrition and Metabolism by Nascimento et al. (Nascimento. 2014) - it's not essentially new, but actually quite a nice reminder of the fat that what I said about l-arginine in the nitrate article was not all made up.

An addendum to the nitrate study: Even a persistent 5% reduction in RMR would not necessarily inhibit weight loss + you can argue that your body needs less energy / oxygen, because it works more effectively and contrary to common believe that's what a true ergogenic should do!

In the introduction to the said article, I already hinted at and linked to the potential weight loss benefits of l-arginine. In spite of the fact that it is literally useless as an NO-booster (remember without increase in NOS, the enzyme that produces NO from arginine, simply piling up more arginine in your blood will only lead to increases in uric acid), previous studies have already shown that L-arg improves the metabolic profile of people with suboptimal health status.

• Schulze et al.. for example, observed that l-arginine speed up the triglyceride-lowering effect of simvastatin in patients with elevated plasma triglycerides (Schulze. 2009)

• El-Kirsh et al. found that both, L‐arginine and L‐citrulline supplementation ameliorated the biochemical parameters and blunted arthesclerotic lesions in high‐fat and high‐cholesterol‐fed rats (El-Kirsh. 2011)

Other studies report beneficial effects on blood pressure and - as discussed in the anti-diabetes series - an ameliorating effect on the blood glucose levels of diabetic and/or insulin resistant individuals (McKnight. 2010; Dong. 2011).

So, the results of this most recent study don't really come as a surprise

In view of what we already knew about l-arginine, the results of the Nascimento study, i.e. reductions in  LDL cholesterol and NEFA levels, in response to the ingestion of 3x2g of pure l-arginine per day in this double blind, randomized crossover study don't come as a surprise.

Figure 1: Changes in triglycerides, total & LDL cholesterol and NEFA levels in response to exercise, only (control) and exercise + arginine (arginine) supplementation; figures in boxes ind. inter-group diff. (Nascrimento. 2014)

What's "news", though, is the interaction with exercise that sheds a whole new light the good old NO-Xplode (learn more, but keep in mind that one characteristic feature of this products is and was being totally underdosed) and its identical clones! I mean, who would have expected that he was buying a health supplement that potentiates the beneficial effects of exercise, in this case...

• 

  The official SuppVersity Supplement Shoot-Out!
  The longstanding veteran, NOXplode AVPT,
  is challenged by a clone of its own, 
  NOXplode 2.0 Advanced Strength -
  which will be the last pre-workout standing?

  four acute, machine-based resistance training sessions
• stretching + general warm-up and cool down before / after sessions
• three sets of 12 repetitions; 60% of the 1RM; 60s rest between sets
• starting with large, ending with small muscle groups
• large muscle groups: Chest press, leg press, pull down, leg extensions
• small muscle groups: Deltoid machine, leg curl, biceps curl, triceps pulley

...on the potentially artherogenic low-density lipoprotein (LPL) and the amount of pro-diabetic non-esterified fatty acids in his bloodstream? You did? Well... I should have anticipated that, Mr & Mr Smar Alec ;-)

There is one question left to answer: What exactly is the mechanism here? I know that some of you won't care - as long as it works - but let's be honest, wouldn't it be nice to know? Well, acute and chronic exercise increase have already been shown to increase the activity of lecithin-cholesterol aciltransferase (L- CAT), the enzyme responsible for the cholesterol ester transfer to HDL, which will then evacuate the cholestrol from the circulation. If this effect is either increased or the transport facilitated by l-arginine, this would explain the reduction in LDL the researchers observed in the study at hand.

Figure 2: The short-term improvements in adiponectin Nascrimento et al. observed stand in line with the well-known long-term improvements in blood glucose management.

Moreover, studies by Tan et al. (2011) suggest that L-arginine will have direct effects on the expression of fat-metabolic genes in skeletal muscle and white adipose tissue, which favor lipogenesis in the muscle (not a problem if those lipids are subsequently burned as fuel during workouts) and a reduced storage of fat in the adipose organ. In conjunction with its proven ability to stimulate mitochondrial biogenesis and brown adipose tissue development (McKnight. 2010) and the previously discussed effects on WAT,  hyperphagia,  improved insulin sensitivity and - much contrary to nitrate (learn more) - increased energy expenditure (albeit only on low protein diets; Clemmensen. 2012). In sum these effects would appear to be profound enough to explain the observations in the study at hand, and those I reported in previous SuppVersity articles on l-arginine - specifically those discussing the potential fat burning (more) and anti-diabetic / glucose lowering effects (more).

Whether that's reason enough for you to begin supplementing again, is yet probably a question of your current metabolic state... if you are by no means like the seven overweight, hypertensive men, non-smoking and sedentary with a mean age of 46±5 yrs and a body weight of 93.1±12.0 kg, ain't insulin resistance, or have high cholesterol levels, it's pretty unlikely that you will see huge benefits.

References:

• Clemmensen, Christoffer, et al. "L-Arginine improves multiple physiological parameters in mice exposed to diet-induced metabolic disturbances." Amino acids 43.3 (2012): 1265-1275.
• Dong, Jia-Yi, et al. "Effect of oral L-arginine supplementation on blood pressure: a meta-analysis of randomized, double-blind, placebo-controlled trials." American heart journal 162.6 (2011): 959-965.
• El‐Kirsh, Amal Ashmawy Ahmed, et al. "The effect of L‐arginine or L‐citrulline supplementation on biochemical parameters and the vascular aortic wall in high‐fat and high‐cholesterol‐fed rats." Cell biochemistry and function 29.5 (2011): 414-428.
• McKnight, Jason R., et al. "Beneficial effects of L-arginine on reducing obesity: potential mechanisms and important implications for human health." Amino acids 39.2 (2010): 349-357.
• Schulze, Friedrich, et al. "L-Arginine enhances the triglyceride-lowering effect of simvastatin in patients with elevated plasma triglycerides." Nutrition research 29.5 (2009): 291-297.
• Tan, Bie, et al. "Dietary L-arginine supplementation differentially regulates expression of lipid-metabolic genes in porcine adipose tissue and skeletal muscle." The Journal of nutritional biochemistry 22.5 (2011): 441-445.

Intra-Workout Supplementation: Increased Carbohydrate Oxidation with L-Arginine, Lower Fat Oxidation with Glucose & Lowest Rate of Perceived Exertion with Plain Water

Image 1: This bird certainly knows about the importance of adequate hydration ;-)

Have you been at the gym today? If so, what kind of beverage have you been sipping in the rest-periods between your sets, your sprints or during your regenerative (not fat burning ;-) "classic" cardio exercise? Was it Funky XYZ the latest and greatest intra-workout product on the market? If so, you better check out its ingredients, who knows maybe the "latest and greatest" turns out to be quite counterproductive towards the goals you have been setting after reading one of the last two installments of the Intermittent Thoughts? Let's assume you are the "Peter Griffin"-type of chubby - in that case, I hope that your Funky XYZ did not contain glucose, maltodextrin, waxy maize, or any other of the sugars of which the supp companies are going to tell you that they "superior" to the white poison your granny uses in her delicious muffins. Why? Well, according to a soon to be published study by scientists from the Massey University in Wellington, New Zealand, as little as 12g of glucose will reduce the amount of endogenous fatty acid (i.e. the stuff your body is using to hide your abs ;-) oxidation by -22%! Sounds terrible, doesn't it? Well, let's look at some details to decide whether those -22% will really make a difference and what effects the presence of l-arginine and l-glutamine in your intra-workout supplement could have had.

150 min @ 177 Watt + Glucose + (Glutamine or L-Arginine) = ???

Figure 1: Composition of the intra-workout supplement; sodium citrate base + 12g glucose (glucose) and additional 1g l-glutamine (Glu + L-Glutamine) or 0.1g l-arginine (Glu + L-arginine)

It stands out of question that adequate hydration is of utmost importance, when it comes to maximizing athletic performance (incidentally, the same is true, when it comes to "burning fat"). What athletes should drink before (pre-hydration), during (hydration) and after your workouts (re-hydration) is thusly one of the classic topics of exercise science and the recent study by D.S. Rowlands et al. is thusly probably #1001 on the never-ending list of investigations into the optimal mineral and nutrient composition of intra-workout drinks. For us, it is of interest, because it is one of the few which investigated the differential effect of the amino acids l-arginine and l-glutamine on substrate utilization, plasma glucose, lactate and sodium levels and rates of perceived exhaustion in eight male cyclists and triathletes during 150min (!) of cycling at 50% of the individually predetermined peak power (this is noteworthy, because 50% of their peak power equalled 177 W, which is not exactly "light" exercise), in the course of which the athletes consume 150ml of a fluid containing a 0.95g sodium base and either 12g of glucose alone or a combination of glucose and either 1g of l-glutamine or 0.1g of l-arginine (cf. figure 1).

Figure 2: Oxygen consumption (L/min) and substrate utilization (g/min) in 8 trained cyclists / triathletes during 150 min of cycling at 177W with 150ml of four different intra-workout drinks (data adapted from Rowlands. 2011)

As a seasoned student of the SuppVersity, it should not surprise you that the exogenous (i.e. from the outside) supply of glucose produced a -22% shift in substrate oxidation from fatty acids to the now more readily available carbohydrates (cf. figure 2). What you have probably not expected, though, is that the addition of the minuscule amount of l-arginine (which is btw. about what you will get with many of the proprietary blends in the still incredibly popular "NO-boosters") would promote this shift by increasing the total amount of oxidized carbohydrates by another ~10% over the 12g glucose solution alone.

Figure 3: Comparison of total / relative substrate utilization for the 12g glucose + 0.1g arginine, the 12g glucose and the water + sodium citrate groups (data adapted from Rowlands. 2011)

Now you are stunned, hah? So after all it is yet not your fault that you cannot see your abs. It's your NO-suppement! Well, not exactly. I mean take a look at the way I arranged the data in figure 3. You will probably acknowledge that the 12g glucose + 0.1g l-arginine group "burned" more energy - if you want it in calories (remember this is stupid ;-) 0.68kcal/min or 102kcal during the whole session and then come back to the -22% reduced fatty acid oxidation and lament: "But Dr. Andro, they burned 22% less fat than the water-only group! Now I know why I don't get lean." If that is your train of thought, I would invite you to continue the idiotic kcal number crunching and calculate on how much fat the poor l-arginine group would have missed to burn... well, it's the "exorbitant" amount of 170mg/min or - for the whole session 25.5g! While this may be more than one tablespoon of coconut oil, I guess you will probably admit that this probably is not the reason your abs are still covered by a thick layer of flabby adipose tissue, won't you?

Arginine reduces oxygen cost at the expense of glucose

Now, the real interesting findings of the studies are thusly not the changes in substrate utilization but rather the profound impact the addition of the two amino acids had on the lactate levels during the 150min of cycling (cf. figure 4) and the rates of perceived exertion (RPE).

Figure 4: Plasma lactate levels (mmol/L) in 8 trained cyclists / triathletes during 150 min of cycling at 177W with 150ml of four different intra-workout drinks (data adapted from Rowlands. 2011)

The latter (RPE), and this is actually quite surprising, were minimal in the water + sodium citrate group and maximal in the 12g glucose + 1g l-glutamine group (0.8 pts greater on a 0-7 scale). The RPE values of the arginine group, on the other hand, were only marginally elevated and that despite the significant increase in glucose clearance, which, by the way, has also been observed by McConell et al. (McConell. 2006) and Linden et al. (Linden. 2010). 

In view of recent studies such as Greer et al. (Greer. 2011), who observed a small, but statistically significant decreases in endurance during a strength training circuit in response to Arginine-Alpha-Keto-Glutarate (AAKG) supplementation, it is yet very unlikely that the observed effects of an arginine-enriched glucose containing intra-workout supplement observed in this study "have the potential to benefit endurance exercise performance" (which is what the scientists, much to my surprise, conclude). Another thing is yet more than likely, I would even say it is 100% certain: Neither the results of this nor of any future study will change the sales ranks on Bodybuilding.com & Co., where the purported NO-Boosters (and factual stimulants) still are the front-runners of the "TOP 10 selling products" ;-)

Beyond Nitric Oxide II: Arginine & Citrulline Modulate Blood Lipids & Liver Fatty Acid Composition And Ameliorate Aortic Lipid Deposition in High Fat Fed Rats

Image 1: The mouse on the left probably
had too little arginine in its high fat diet
(just kiddin' ;-)

This is a follow up not on yesterday's third, but on the second installment of the Amino Acids for Super Humans series on Carl Lenore's Super Human Radio. In that episode I had already alluded to the metabolic benefits of arginine and citrulline supplementation, which reach far beyond their purported use as ergogenic aids and nitric oxide booster. A very recent study (El Kirsh. 2011) published a week ago ahead of print in the online issue of Cell Biochemistry & Function confirmed and expanded on the results of previous studies which showed beneficial effects on parameters of organ (specifically heart and liver) in rodent models.

6 groups of rats fed either a normal diet or the dubious "high fat" diet, scientists use to induce obesity along with the characteristic symptoms of the metabolic syndrome (insulin resistance, arteriosclerosis, etc.) were fed one of the following diets:

• group 1: normal food, no supplement
• group 2: normal food, arginine (100mg/kg; human equivalent 16mg/kg)
• group 3: normal food, citrulline (100mg/kg)
• group 4: high fat diet (HFD), no supplement
• group 5: high fat diet (HFD), arginine (100mg/kg)
• group 6: high fat diet (HFD), citrulline (100mg/kg)

Both the negative effects of the high fat diet, as well as the ameliorative effects of arginine and citrulline on serum transaminase levels (indicators of liver "activity" /high levels are mostly interpreted as signs of liver damage), triglycerides, cholesterol levels and indices of atherosclerosis were profound:

HFD feeding increased significantly serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities, urea and all lipid profiles and decreased significantly serum high-density lipoprotein-cholesterol (HDL-c) and non significantly serum nitric oxide levels. L-arginine or L-citrulline administration reversed the increase in serum AST and ALT activities, urea and all lipid profiles.

As it can be seen in figure 1, the positive effects of arginine and citrulline even went beyond the mere amelioration of the detrimental effects of the high fat diet by increasing HDL-c and nitric oxide levels, decreasing the count of dangerous V-LDL particles even compared to normal diet and modulating the relative percentages of 18 : 0, 20 : 0 and 22 : 6 to 16 : 0 fatty acids in the livers of the rats on the high fat diet.

Figure 1: Triglyceride and cholesterol levels of rats fed normal chow (control) and rats on a high fat diet (HFD) supplemented with either arginine (HFD+Arg) or citrulline (HFD+Cit) (data adapted from El Kirsh. 2011)

Moreover, the beneficial effects on heart health that are generally ascribed to such improvement in blood and tissue markers could actually be confirmed by light and transmission electron microscopic images of the thoracic aorta. While the HFD group that did not receive supplemental arginine or citrulline "demonstrated structural changes in the endothelial cells of the intimal layer, medial smooth muscle cells as well as in the adventitial layer", there was only "little structural alterations in animals supplemented with L-arginine or L-citrulline along with HFC feeding".

Taken together, these and the results I reported in the aforementioned episode of Amino Acids for Super Humans should well be able to change your perspective on your favorite pre-workout product forever - even if it does not give you the pump the fancy ad you saw when you bought it promised, it may well save your organs from the consequences of one or another dietary faux pas. I hope, I do not have to tell you, though, that it would border on or rather be plain nutritional idiocy, if you used arginine and citrulline to make up for the consumption of the famous westernized high fat, high carb, low protein fast food diet (which would be similar to the HFD the rats consumes)!

Synephrine More Ergogenic, Than Thermogenic? Pump Supps Revisited - L-Arginine, L-Citrulline and Respective Whey-Peptides & -Nitrates | ISSN Research Review '15 #2

Synephrine, arginine, citrulline - Which pre-workout ensures that you're "on fire"?

As I pointed out previously, my initial idea to cherry pick only the most interesting study results that were presented in form of of poster presentations at the Twelfth International Society of Sports Nutrition (ISSN) Conference and Expo in 2015 didn't work out. The number of interesting studies is is simply too much for a single SuppVersity article to discuss them all.

Accordingly, I am now posting the 2nd serving of what is going to be a multi-part series of articles with brief discussions of the most significant results of the >20 studies and short references to those that didn't make the SuppVersity cut in this, previous and future installments of this series for one reason or another.

Read more about ISSN and other studies at the SuppVersity

Vitargo, Red Bull, Creatine & More | ISSN'15 #1

Pump Supps & Synephrine & X | ISSN'15 #2

High Protein, Body Comp & X | ISSN'15 #3

Keto Diet Re- search Update | ISSN'15 #4

The Misquantified Self & More | ISSN'15 #5

BCAA, Cholos-trum, Probiotics & Co | ISSN'15 #6

• Synephrine More Ergogenic Than Thermogenic? There was not just one, but two poster presentations and a full paper that has been published only days ago on synephrine containing supplements at the ISSN meeting and on the ISSN website, respectively. Synephrine? Yes, that's the supplemental non-starter, ah... I mean allegedly powerful fat burner from orange peels. The one with promising fat loss results in rodents, but discouraging results in practice.
  
  Luckily, the studies that were presented in form of posters by scientists from the Texas A&M University (Jung. 2015 & Dalton. 2015) at the ISSN meeting did not deal with synephrine as fat burner. Rather than that, Jung et al. and Dalton et al. took a look at the short- and long-term safety of synephrine as a pre-workout. A pre-workout that contained either 3g beta alanine, 2g creatine nitrate, 2g arginine AKG, 300mg N-acetyl tyrosine, 270mg caffeine, and 15mg Mucuna pruriens, alone (PLA) or the same baseline ingredients and synephrine.
  

  

  Figure 1: Number of reps on sets 1-3 & 4-6 in the control and treatment conditions (Ratamess. 2015)

  Now, the fact that some synephrine in your preworkout won't kill you is not really exciting. I have to admit that. What is exciting... at least sort of, though is the fact that the questionable thermogenic turned out to be an effective ergogenic in the already published and thematically related study by Ratamess and colleagues (Ratamess. 2015). A study that shows that p-synephrine of which previous studies indicate that it is a potent, but highly selective β-3 adrenoreceptor may nor be the best fat burner (the good old ephedrine was a pan-receptor activator and clenbuterol & co target the β-3 receptor, maybe that's also why the fat loss results are rather disappointing) , but at least an underestimated ergogenic.

Is p-synephrine different from synephrine? That's a good question without a clear question. Most supplements that list synephrine on the label actually contain P-hydroxy-α-{methylaminomethyl}-benzylalcohol aka p-synephrine, a protoalkaloid compound that differs from m-synephrine and o-synephrine structurally and comes in form of to stereoisomers in most supplements - the l-enantiomer and the d-enantiomer as the racemate d,l-synephrine. While the latter have been shown to be present in bitter orange, other forms, like the m,s-isomer may are suspected to be adulterations from synthetic phenylephrine supplement producers use to "spike" (Allison. 2005) their products (I assume this was not the case with the samples the researchers in the study at hand used, but the chaos wrt to the types of synephrine puts a huge "?" behind the assumption that you'll see the same effects from any given synephrine or synephrine + caffeine supplement. 

• As the data in Figure 1 goes to show you, the p-synephrine supplement, which was administered to twelve healthy, college-aged men at a dosage of 100mg either alone (S) or in conjunction with 100 mg caffeine (SCF) for three days. On the day on which the subjects participated in a standardized resistance exercise protocol consisting of 6 sets of squats for up to 10 repetitions per set using 80 % of their one repetition-maximum (1RM) with 2 min of rest in between sets, the supplement was ingested 45 minutes before the workout. In comparison to the placebo treatment synephrine alone triggered a significant increase in total repetitions and volume load. When synephrine was combined with 200 mg of caffeine, it also increased the mean power and velocity of squat performance. What did not change in response to either synephrine alone or caffeine and synephrine, though, were the blood lactate levels or the rate of perceived (RPE) exertion the subjects reported on the usual visual analogue scales.
  
  For me personally, that's a surprising result. For the scientists it "indicate[s that] supplementation with S and SCF can enhance local muscle endurance during resistance exercise" (Ratamess. 2015); and I have to admit: They are right. One thing you should keep in mind, though, is that unlike caffeine, where you often see reductions in RPE and thus an effect you will feel, synephrine will - even if it works - do its purported "magic" more subtly.
• The Latest on "Pump Supplements" - Creatine, Arginine, Citrulline, Nitrates -- To make sure that this series is not turning into a 12-part article, I will address the results of Moon's, Suzuki's and Vogel's results in one item (since Moon's paper basically summarizes the results of studies by Falcone and Joy, I won't discuss those separately) .
  
  

  

  Figure 2: Increases in blood flow volume (BFV) 33 minutes after the ingestion of 1.87g of RC, 3.67g of CP (citrulline content 1.87g), 1.87g of RA, or 3.07g of AP (arginine content 1.87g) before 3 sets of 15 arm curls (Moon. 2015).

  Moon et al.'s comparison of citrulline's and arginine's ability to increase the exercise-induced vasodilation and blood flow yielded unsurprising results that confirm that citrulline-based ingredients are more effective than arginine-based ingredients for modulating vasodilation and blood flow. Now that alone wouldn't be news-worthy if the scientists had not tested the effects of both, rawe L-citrulline (RC) and raw L-arginine (RA) and, citrulline and arginine bound to a whey peptide (CP and AP, respectively).
  
  I guess I am not going to surprise you, when I tell you that regular arginine was the worst vasodilator in this quartet. What is more surprising, though, is the extent to which the peptide bonding increased the vasodilating effects of regular citrulline and even arginine. With the the former producing 2x higher increases in vessel diameter and 9% higher increases in blood glow volume than regular citrulline (let's not even mention regular arginine | see Figure 2) the effects are pronounced enough to be potentially "feelable" and "visible" during a workout.
  
  

  

  Citrulline & Glutathione - GSH Amplifies & Prolongs CIT's NO Boosting Effects During + After Biceps Workout | learn more.

  Against that background I would be curious to see, whether the likewise recently reported performance enhancing effects of citrulline Suzuki et al.'s observed in twenty two well-trained young men who consumed 2.4 g / day of L-citrulline or placebo for 7 days and they took 2.4 g of L-citrulline or placebo 1 hour before 4 km cycling time trial on day 8 would be enhanced by bonding citrulline to whey peptides.
  
  I mean, if citrulline-whey-peptides appear to offer the same effects citrulline does, but at a higher efficacy, their beneficial effect on cycling time trial performance of which the Suzuki et al. argue that it was mediated by an up-regulation of plasma NO availability should be superior to that of raw citrulline, as well, right?
  
  And now that we are already talking about what really matters, i.e. performance enhancements, not increases in blood flow, it would also be interesting to see a follow up on the last "pump supplement" study to be mentioned in this installment of the ISSN Research Review: A study by Vogel et al.'s on the vasolidating effects of an arginine-nitrate based pre-workout supplements that shows significant increases in brachial artery diameter. Increases that are quantitatively similar to those Moon et al. observed for citrulline-whey-peptides in the previously discussed study. That does not mean, though that they are equally effective, though. To be able to say that we would need a study in which both agents are compared head-to-head. Unless this study is done and a follow up on Vogel's study proves that the increases in blood flow will actually produce significant performance gains, the only thing I can say about arginine nitrate is: It's interesting, but with respect to its ergogenic effects more studies have to be done.

You don't believe citrulline can do anything for you? Check this out: 8g/day Citrulline Increase Leg Workout Performance - More Reps on Leg Press, Hack Squat & Leg Ext. in Exp. Gymrats (more)! It is thus by no means useful for "cosmetic pumps", only 

Studies that didn't make the cut in this issue are Brooke Bouza et al.'s study on the exercise and calorie information on menus (Bouza. 2015) as well as O'Conner et al.'s tart-cherry study (O'Connor. 2015). That's not because there were methodological issues or something. It's much simpler: The notion that "exercise and calorie information on menus is not enough to improve food choices in Hispanic adults" (Bouza. 2015) is about as unsurprising as the word "potentially" (O'Connor. 2015) in the conclusion of O'Connor's study is daunting. And by the way, now that you know that tart cherry "potentially increases running performance and attenuates post-race markers of inflammation" you actually know the most relevant finding of O'Connor's study, right? | Comment on Facebook!

References:

• Allison, D. B., et al. "Exactly which synephrine alkaloids does Citrus aurantium (bitter orange) contain?." International journal of obesity 29.4 (2005): 443-446.
• Bouza, Brooke, et al. "Exercise and calorie information on menus is not enough to improve food choices in Hispanic adults." Journal of the International Society of Sports Nutrition 12.Suppl 1 (2015): P3.
• Dalton, R., et al. "Safety and efficacy of a pre-wrkout dietary supplement with and without synephrine." Journal of the International Society of Sports Nutrition 12.Suppl 1 (2015): P5.
• Falcone, Paul H., et al. "Acute hemodynamic effects of L-arginine, arginine nitrate, and arginine peptide on exercise-induced vasodilation and blood flow in healthy men." Journal of the International Society of Sports Nutrition 12.Suppl 1 (2015): P10.
• Joy, Jordan M., et al. "A comparison of raw citrulline and citrulline peptide for increasing exercise-induced vasodilation and blood flow." Journal of the International Society of Sports Nutrition 12.Suppl 1 (2015): P18.
• Jung, Y. P., et al. "Effects of 8 weeks pre-workout dietary supplement ingestion with and without synephrine on blood chemistry panel." Journal of the International Society of Sports Nutrition 12.Suppl 1 (2015): P4.
• Moon, Jordan R., et al. "A comparison of citrulline and arginine for increasing exercise-induced vasolidation and blood flow." Journal of the International Society of Sports Nutrition 12.Suppl 1 (2015): P6.
• O'Connor, A., et al. "Short-term powdered tart cherry supplementation encircling an acute endurance challenge potentially increases running performance and attenuates post-race markers of inflammation." Journal of the International Society of Sports Nutrition 12.Suppl 1 (2015): P7.
• Suzuki, Takashi, et al. "Oral L-citrulline supplementation enhances cycling time trial performance in healthy well-trained males." Journal of the International Society of Sports Nutrition 12.Suppl 1 (2015): P52.
• Vogel, Roxanne M., et al. "Acute hemodynamic effects of a multi-ingredient performance supplement on brachial artery vasodilation and blood flow volume following elbow flexion exercise in healthy young men." Journal of the International Society of Sports Nutrition 12.Suppl 1 (2015): P28.