Friday, December 12, 2014

No Advantage of Bolus Ingestion of EAAs in Young Men!? Cereal Bread Not Better for Weight Control. Saturated Fat & the Heart. Plus: Serine for Your Weekend Alcohol Binge!

The "muscle full effect" indicates you don't have to consume 4 scoops at once.
With the publication of the latest issue of The Journal of Nutrition came a handful of interesting scientific papers I will briefly introduce in today's SuppVersity Nutrition Science Update.

The corresponding studies deal with the link of saturated fat to heart disease (Puaschitz. 2014), the effects of proteinogenic amino acid serine (one of the non-essential amino acids) on homocysteine metabolism in a rodent model of alcoholic fatty liver disease (Sim. 2014).

And when we're through with those, we will take a closer look at the effects of cereal enriched breads on the appetite ratings and postprandial glucose, insulin, and gastrointestinal hormone responses related to hunger and satiety in healthy men and women (Gonzalez-Anton. 2014), and the "muscle full effect", or rather limits to maximal protein synthesis in man (Mitchell. 2014).
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  • Saturated fat and your heart - Right from the Haukeland University Hospital in Norway comes a new study that investigated the associations between self-reported dietary SFA intake and risk of subsequent coronary events and mortality in patients with coronary artery disease (CAD).

    The study included patients who participated in the Western Norway B-Vitamin Intervention Trial and completed a 169-item semiquantitative food-frequency questionnaire after coronary angiography - 2412 patients, total, 81% men, 19% women with a mean age of 61.7 y.
    After a median follow-up of 4.8 y, a total of 292 (12%) patients experienced at least one major coronary event during follow-up.  And while a gigh intake of SFAs was associated with a number of risk factors at baseline, "there were no significant associations between SFA intake and risk of coronary events [age- and sex-adjusted HR (95% CI) was 0.85 (0.61, 1.18) for the upper vs. lower SFA quartile] or any secondary endpoint. Estimates were not appreciably changed after multivariate adjustments" (Puaschitz. 2014).
    Figure 1: Hazard ratios according to % saturated fat intake of total energy intake compared to minimal saturated fat intake (HR = 100%) in 2412 subjects (Puaschitz. 2014).
    In other words, if you ask researchers from Northern Europe, their answer to the question, whether our high intake of saturated fats is the reason we are dying prematurely from heart disease is "no". This stand in line with a recent review of the current evidence by O'Keffee et al. who point highlight that the different results (which often depend on the country, where the studies are conducted) may be attributable to the fact that "not all SFA are created equal and the food sources of SFA". Accordingly the researchers from the King's College in London, the Luke’s/Roosevelt Hospital, the New York Nutrition Obesity Research Centre and the Columbia University in New York recommend that "individual characteristics of the SFA, such as chain length, should be considered in dietary recommendations" (O’Keeffe. 2014)... and I would like to add: In every future study, as well.

    I mean, this and the foods from which the subjects in the study at hand got the majority of their saturated fat intake may well be the reason that there was a statistically significant correlation between high fat intakes and the occurernce of coronary artery disease (remember: all participants had CAD, already) in the cohort Western Norway B-Vitamin Intervention Trial.
  • L-Serine as super-supplement for binge drinkers? At least in rodents the provision of 200mg/kg body weight (for humans this would be ~1.2-1.5g/day) serine in the diet led to an attenuation of alcohol-induced increases in serum homocysteine and hepatic triglyceride (TG) concentrations (>5-fold in the control mice) by 60.0% and 47.5%, respectively.
    Figure 2: Liver triglyceride levels, serum ALT and serum homocysteine levels in control mice (C) and "binge drinking mice" (EV) with and without 20mg/kg (ES20) and 200mg/kg (ES200) serine in their diets (Sim. 2014)
    Moreover, in the chronic ethanol study, l-serine also decreased hepatic neutral lipid accumulation by 63.3% compared with the ethanol group and ramped up the glutathione and S-adenosylmethionine content of the liver by 94.0% and 30.6%, respectively.

    If we assume that serine is only half as powerful, when it is given to humans, I would recommend you drink your Vodka Red Bull with serine in the future ;-)
  • Super-satiating cereal enriched breads - I guess "super-satuating" is an exaggeration, but there is no doubt that the addition of variety of cereal flours (wheat, oat, and spelt) and 22% dried fruits (figs, apricots, raisins, and prunes) to regular bread lead to a significant improvement of appetite control by reducing hunger and enhancing satiety in 30 healthy adults (17 men and 13 women) aged 19–32 y with body mass index of 19.2–28.5 who participated in an experiment that was conducted at the University of Granada in Spain (Gonzalez-Anton. 2014).
    Figure 3: The hormonal changes would indicate increased satiety, the subjects reported increased satiety, but their 4h energy intake was identical in both condition (Gonzalez-Anton. 2014)
    Whether the decrease in prospective consumption and increased satiety is enough to have long-term benefits on weight control is yet questionable, because the subsequent ad libitum energy intake in a 4 h period after the ingestion of the "enriched" bread did not differ from that in the control condition, even though the postprandial blood glucose, insulin, ghrelin, were lower and the pancreatic polypeptide AUC (an indicator of satiety) was higher than with the control bread.

    Speaking of insulin: In view of the fact that the latter actually is a satiety hormone and its release is closely related to glucagon-like peptide (GLP) 1 and gastric inhibitory polypeptide (GIP) where the AUC (areas under the curve) were lowered as well, it's eventually maybe not too surprising that the "enriched" bread was not better than the regular one.
  • Muscle full? What's limiting protein Synthesis? Scientists from the Clinical, Metabolic, and Molecular Physiology, MRC–Arthritis Research UK Centre of Excellence for Musculoskeletal Ageing Research at the University of Nottingham and the Royal Derby Hospital in the United Kingdom recently determined the effect of Bolus (=all the aminos at once) vs. Spread EAA feeding in young men, hypothesizing that muscle-full is regulated by a dose-, not delivery profile–, dependent mechanism; and what they found was surprising for us - not for the researchers, though:
    Figure 4: Even though the study was conducted in young men, the overall dosage of 15g may potentially have had an effect on the outcome. On the other hand: If you "overdose" it would actually be more likely for spread protein ingestion to have superior effects. Against that background the "low" dose of "only" 15g of pure EAAs is not an argument that would falsify the results of the study at hand (Mitchell. 2014)
    "Despite distinct plasma and muscle profiles, Bolus feeding provided no anabolic advantage over Spread feeding (or vice versa); these findings are in keeping with our hypothesis of there being an intrinsic muscle-full state in young men at rest.

    Bolus feeding led to rapid aminoacidemia with a brisk upstroke and high peak plasma EAA and leucine concentrations. Spread feeding, by comparison, resulted in lower, later peak concentrations. Despite this, identical MPS responses were observed, even with the same latency (of ~90 min) and amplitude.

    Furthermore, with both feeding strategies, basal MPS was observed 180 min after consumption of either Bolus or the initial Spread doses. This preceded the peak Spread plasma EAAs, in keeping with the onset of a muscle-full state.
    As the scientists point out, their results do thus "suggest that, in healthy young men, it is dose dependent mechanisms that regulate the size of the anabolic response to feeding and that this response" and that this dose-dependent anabolic response "is not perturbed by later arriving, lower-amplitude aminoacidemia." The researchers also highlight hat it would seem "vital to have such a mechanism in place"; because of the "stability of muscle mass from year to year in healthy younger populations" (Mitchell. 2014). Eventually, the differences may well be explained by the existence of three distinct phases in the postprandial period, the scientists argue:
    Figure 5: Absolute changes in FSR from fasted (2120 to 0 min) to fed (0 to 240 min) (A), actual FSRs (B) and plasma EAA and insulin concentrations, phospho- 4EBP1 Thr65/70 and muscle protein synthetic rates, normalized to their own data spans shown on the same axis (C and D) in young men after consumption of 15 g of mixed-EAA meals by Bolus or Spread treatment. The black arrows represent ingestion of 15 g EAAs once, and the gray arrows represent ingestion of 3.75 g EAAs 4 times (Mitchell. 2014)
    "After the onset of essential aminoacidemia, a latent period exists when a significant negative arteriovenous EAA balance is detectable (Mitchell. 2013) but incorporation of EAAs into newly synthesized myofibrillar proteins is not. The existence of a similar latent period in response to Bolus and Spread EAA ingestion suggests that providing time for adequate intracellular EAA accumulation, even with rapid aminoacidemia with Bolus, is crucial before MPS can be ‘‘switched on.’’ After this latent period, a transient stimulation in MPS, lasting ;90 min (Bohé. 2001), occurs before the onset of the muscle-full state restores basal MPS despite sustained, near-peak postprandial EAA availability" (Mitchell. 2014).
    Put simply, it takes long enough for the muscle protein synthesis to gain full speed to incorporate all the amino acids the healthy subjects received in 4x45min boluses.

    Practically speaking this does not necessarily mean that you should give up your previous protein feeding strategies. With intact proteins, of which you know that they are more than the sum of their EAA parts (see "Whey Beyond Brawn"), studies by Moore et al. (2012 | learn more) and Burke et al. (2012 | learn more) yielded different results... albeit with less frequent biopsies that were taken across the postprandial period and thus a lower temporal resolution that does not exclude that said studies simply overlooked the dose-dependency of the muscle-full effect Mitchell et al. demonstrate in the study at hand.
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So what are the take home messages from today's research update? I guess the one you will be most interested in, is the related to the Mitchell study which indicates that protein timing and / or the importance of bolus ingestions may previously have been overrated - at least in the short run. We should not forget, after all, that this is a result that would stand in line with Alan Aragon's & Brad Schoenfeld's recent review (Aragon. 2014  on nutrient timing which found a significant effect for the amount of protein people consume, but no evidence of the purported importance of protein timing.

This is yet not the only myth that is tumbling. The idea of heart disease triggering saturated fats and the notion that you could make bread a superfood by adding cereals and dried fruits did not get away unscathed either. With the impressive effects of serine in the rodent study by Sim et al. (2014), we do have another myth to bother with - one of which I would like to remind you that it has to remain a myth until the results have been confirmed in human beings | Comment on Facebook!
References:
  • Aragon, Alan Albert, and Brad Jon Schoenfeld. "Nutrient timing revisited: is there a post-exercise anabolic window." J Int Soc Sports Nutr 10.1 (2013): 5.
  • Bohé, Julien, et al. "Latency and duration of stimulation of human muscle protein synthesis during continuous infusion of amino acids." The Journal of physiology 532.2 (2001): 575-579.
  • Burke LM, Hawley JA, Ross ML, Moore DR, Phillips SM, Slater GR, Stellingwerff T, Tipton KD, Garnham AP, Coffey VG. Preexercise aminoacidemia and muscle protein synthesis after resistance exercise. Med Sci Sports Exerc. 2012 Oct;44(10):1968-77.
  • O’Keeffe, Majella, and Marie-Pierre St-Onge. "Saturated Fat and Cardiovascular Disease: A Review of Current Evidence." Current Cardiovascular Risk Reports 7.2 (2013): 154-162. 
  • Mitchell, William Kyle, et al. "Development of a new Sonovue™ contrast‐enhanced ultrasound approach reveals temporal and age‐related features of muscle microvascular responses to feeding." Physiological reports 1.5 (2013). 
  • Mitchell, William Kyle et al. "A Dose- rather than Delivery Profile–Dependent Mechanism Regulates the ‘‘Muscle-Full’’ Effect in Response to Oral Essential Amino Acid Intake in Young Men."J. Nutr. February 1, 2015
  • Moore DR, Areta J, Coffey VG, Stellingwerff T, Phillips SM, Burke LM, Cléroux M, Godin JP, Hawley JA. Daytime pattern of post-exercise protein intake affects whole-body protein turnover in resistance-trained males. Nutr Metab (Lond). 2012 Oct 16;9(1):91.
  • Puaschitz et al. "Dietary Intake of Saturated Fat Is Not Associated with Risk of Coronary Events or Mortality in Patients with Established Coronary Artery Disease." J. Nutr. February 1, 2015 jn.114.203505
  • Sim, et al. "l-Serine Supplementation Attenuates Alcoholic Fatty Liver by Enhancing Homocysteine Metabolism in Mice and Rats." J. Nutr. February 1, 2015 jn.114.199711.