Friday, January 4, 2013

Science Round-Up Seconds: Looking at Fast, Slow & Total Protein Intake Again. More Than 2g/kg Protein = Madness?

Just out: Part I of my interview with Sean Casey from CasePerformance. This part of the three-part interview includes a basic protocol that may help you get your macronutrient and energy intake right (I put an emphasis on the word "basic", here ;-).
If you have not downloaded the podcast of yesterday's installment of the SuppVersity Science Round-Up (show starts at ~70min), I suggest that you do that first, because I am not going to repeat what I have said on air already, but will be serving you a second course, instead of the seconds or a "reheated" news from yesterday. Thus listening to the show first will help you understand the relationship between the digestive speed of various proteins and the potential disadvantage of fast digesting amino acids (and proteins) in terms of the net protein retention. And to make the "news dish" even more palatable I am going to season the data and conclusions from the review I mentioned on air with some additional sources and references, as well as two recent studies on protein intake (one with a focus on the elderly).

Just in case you are missing something: Since I personally consider the other studies I did not mention yesterday boring compared to this one, I will focus solely on protein intake and postpone the interesting study snippets to tomorrow's installment of On Short Notice.

As I already mentioned yesterday, the data on protein digestion times and much of what I am going to discuss today comes from a 2006 review of the literature by Bilsborough and Mann (Bilsborough. 2006). Being what it is, namely a review, it does obviously have the downside of deriving the data from various studies. So take the exact values (specifically those in figure 1) with some of the often-cited 'healthy skepticism'. The same goes for the scientists' conclusions, of which the unquestionably most important and probably undisputed one is:
"Rapidly absorbed amino acids despite stimulating greater protein synthesis, also stimulate greater amino acid oxidation, and hence results in a lower net protein gain, than slowly absorbed protein (54). Leucine balance, a measurable endpoint for protein balance, is indicated in Figure 1, which shows slowly absorbed amino acids (~ 6 to 7 g/h), such as CAS and 2.3 g of WP repeatedly taken orally every 20 min (RPT-WP), provide significantly better protein balance than rapidly absorbed amino acids." (my emphasis in Bilsborough. 2006)
Another hypothesis, which does certainly make sense, bu is probably not going to be very popular in the fitness and boydbuilding community is invoked within the following considerations Bilsborough and Mann put on paper:
Figure 1: Protein uptake (mind the different scales on top vs. bottom) from different protein sources in g/h (Bilsborough. 2006)
"This 'slow' and 'fast' protein concept provides some clearer evidence that although human physiology may allow for rapid and increased absorption rate of  amino acids, as in the case of WP (8 to 10 g/h), this fast absorption is not strongly correlated with a 'maximal protein balance,' as incorrectly interpreted by fitness enthusiasts, athletes, and bodybuilders. Using the findings of amino acid absorption rates (using leucine balance as a measurable endpoint for protein balance), a maximal amino acid intake measured by the inhibition of proteolysis and increase in postprandial protein gain, may only be ~ 6 to 7 g/h (as described by RPT-WP, and casein), which corresponds to a maximal protein intake of 144 to 168 g/d." (my emphasis in Bilsborough. 2006)
We tend to ignore and overread things, we don't like, so let me briefly repeat the most important message here: If postprandial protein gain maxes out at 6-7g/h and the day has no more than 24h you math would tell you that eating more than 144-168g of protein per day is bogus.

"You are kiddin' me!? More than 168g/protein per day is bogus?"

Figure 2: The existing differences in fractional protein synthesis (FSR) are "biologically probably insignificant" - in other words given they have the same muscle mass sprinters, bodybuilders and even endurance athletes have the same FSR (Mittendorfer. 2006)
To support their argument that the exuberant protein intake, as it is praticed by fitness enthusiasts, athletes, and bodybuilders who have an incorrect understanding of the relation between fast absorption of proteins and "maximal protein balance" is total bogus, Bilsborough and Mann cite a previous paper by Rennie who reports that the increase in protein synthesis saturates even when amino acids are infused directly and continuously into the blood stream at ~12 g/h for an 80kg individual (Rennie. 2001).

In a similar context, Mittendorfer et al. report in a 2005 paper that the protein synthesis rates in human muscles are neither determined by anatomical location nor fiber-type composition, as the differences they observed were <15% and thus "biologically probably insignificant" (Mittendorfer. 2006). The relative increase in sarcoplasmic and myofibrillar protein synthesis were +100% and +200%, respectively (see figure 1 on the right). It may be possible that you can squeeze a little more after a workout, but let's be honest, you also got to sleep and I would hope you are not even remotely considering hooking yourself up with an AA infusion over night ;-)

"So is protein bad for me?"

Two notes on more recent studies: Deutz and Wolfe are soon going to publish an "opinion paper" in the Journal of Clinical Nutrition that's titled "Is there a maximal anabolic response to protein intake with a meal?" Their answer that it isn't is however misleading, because they are dealing with "high protein meals" of 30g and total protein intakes of 1.5g/kg (Deutz. 2012). Of much greater significance not just in the context of this individual blogpost, but also with respect to the dietary guidelines and thus public health is a paper by Volpi et al. in the Journals of Gerontology in which they demand that the guidelines for protein intake in the elderly have to be revised (Volpi. 2012). Just like me they put a much greater emphasis on the importance of hitting the threshold intake (~30g total protein) with every meal than on the total amount of protein in the diet and point out that the data from the latest NHANES study clearly suggests that older individuals reach this threshold - if anything - with dinner.
Don't get me wrong I don't want to put you off protein (both literally as well as metaphorically ;-) - but there is a physical reality out there that is full of thresholds, which are often more than just upper limits and you can hardly argue with Bilsborough and Mann as far as their conclusion with respect to physically active people and their effort to build and preserve body protein is concerned:
"Diminished reserves of TCAI through restricted carbohydrate intake [which would become necessary if you don't won't to overeat with too much carbs on top of all the protein] could potentially bring about an early onset of fatigue, decrease exercise performance, and promote muscle catabolism. As protein absorption of real foods is approximately 1 to 4 g/h, and fat is absorbed at approximately 14 to 18 g/h, the need for adequate glucose to prevent muscle gluconeogenesis and hence preserve lean muscle is important and further supports the need for a minimum carbohydrate intake, especially for active people. A carbohydrate intake of 120 to 150 g/d could be sufficient with active people consuming > 150 g/d from a large variety of cereals, whole grains, fresh fruit, and vegetables." (Bilsborough. 2006)
Actually I believe there is no additional "bottom line" necessary here (aside from picking the right "whole grains" and "cereals", of course): Protein is the building block for lean muscle tissue, but what happens on a construction site if you have plenty of building blocks, but neither electricity (carbs), nor gasoline (fats) to power the devices (let alone beer to satisfy the workers *rofl*)? Right, nothing happens! And in the end you can be happy if the part of the house that's already standing won't whither away and fall apart...

I guess among you there will be only few who still fall into the category of mislead protein worshipers, but just to make sue: 2g/kg is more than enough and my longstanding suggestion that 1.5g/kg would do as well - if it's from EAA rich protein sources, even better - still stands.


References:
  • Bilsborough S, Mann N. A review of issues of dietary protein intake in humans. Int J Sport Nutr Exerc Metab. 2006 Apr;16(2):129-52.
  • Deutz NE, Wolfe RR. Is there a maximal anabolic response to protein intake with a meal? Clin Nutr. 2012 Dec 1.
  • Mittendorfer B, Andersen JL, Plomgaard P, Saltin B, Babraj JA, Smith K, Rennie MJ. Protein synthesis rates in human muscles: neither anatomical location nor fibre-type composition are major determinants. J Physiol. 2005 Feb 15;563(Pt 1):203-11.
  • Rennie MJ. Control of muscle protein synthesis as a result of contractile activity and amino acid availability: implications for protein requirements. Int J Sport Nutr Exerc Metab. 2001 Dec;11 Suppl:S170-6. 
  • Volpi E, Campbell WW, Dwyer JT, Johnson MA, Jensen GL, Morley JE, Wolfe RR. Is the Optimal Level of Protein Intake for Older Adults Greater Than the Recommended Dietary Allowance? J Gerontol A Biol Sci Med Sci. 2012 Nov 26.

28 comments:

  1. "..focus on the elderly" - Thanks for thinking of me! BTW, our May baby will be a boy, and yes I will then be 72.

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  2. But what about from a natural Bodybuilding perspective?... all naturals when dieting will routinely increase there intake of protein

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    1. you know the old computer game "Lemmings"? Remove the green hair and add some muscle to these creatures and you have the answer

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  3. And Captain Obvious strikes once again. Yeah...

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  4. I just wanted to thank you for highlighting the tryptophan/neurotransmitter issue pertaining to BCAA consumption in your most recent SR podcast. I ditched all the aminos looking back I have to say it was a royal waste of money which gave me crazy bouts of depression, anxiety and low mood.
    Great timing for a post such as this one, I was considering getting some casein hydro [pepto pro] to sip on pre and during my workout. In the light of your findings, however, I might give it a miss and save money on what is offering a substandard net protein balance.

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  5. I am keen to re-join the gym again, I have two worries though.

    1) I've read a bit about CNS fatigue. I will never lift heavy enough to get CNS fatigue. It has made me wonder though, if lifting weights has an effect on mood, neurotransmitters or cognitive health?

    2) I've read that weightlifting causes GERD. I suffers severe GERD. I've read this is because of tensing the stomach/abdomen or holding your breath.

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    1. what people usually refer to as "CNS fatigue" is in fact parasympathetic overtraining and that's usually a result of high volume training and most likely occurs in response to the "training in the fat burning zone", I keep bashing over and over for its stupidity. I rarely recommend BB.com articles, but this is an exception => http://www.bodybuilding.com/fun/berardi22.htm

      Gerd is mostly a consequence of a hernia you may get esp from deadlifting and squatting to heavy while holding your breath. Just learn to master the moves appropriately and you are good to go. People are stupid, they think "When I move the maximal weight from A to B, I train optimally" - that's not only unproductive, it's also downright dangerous

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    2. So wieghtlifting or aerobic exercise has no negative effect on neurotransmitters or cognitive health, as long as you don't overtrain?

      How do I "master the moves", so that Gerd isn't a consequence of weight training?

      Thanks

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    3. If anything, exercise will improve cognitive function. And "master the moves" by "working the muscle". Don't just move weight but focus on performing the lift properly. Start with a low weight and build up so you don't over-do it.

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    4. The BB article says that lifting, unlike aerobic exercise, doesn't increase cortisol. How then would it cause CNS fatigue? The article summarises that CNS fatigue is caused by stress. It does mention that lifting requires neural demand.

      By "master the moves" did you mean what primalkid said, or were you referring to not holding the breath. It is vital that lifting weights doesn't aggravate my gerd, as I get pretty strong reflux.

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    5. Also, if lifting requires neural demand, does this mean even light weightlifting coul impair cognitive function or mood?

      I don't see this as being likely but thought I should ask.

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  6. Does that mean that a meal with 100g+ of real food protein is wasted money or will it just take longer to digest?

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    1. if it does not give you diarrhea it will be digested, so it's not wasted. Don't worry. Just takes longer - the "exact" duration of the digestive process determined by the type of protein and a couple of other factors (e.g. a whole piece of meat will digest longer than the same meat pulverized ;-)

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  7. Extreme newbie question - just to clarify, the protein absorption talked about here is different to protein retention? As my inital thoughts were along the lines of - what caloric conditions exist for this limit of 6-7g p/h to be reached? Because as i understood it, in caloric deficit protein retention dropped, so presumably to reach the rate of 6-7g p/h extra dietary protein would be required?

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    1. yep, correct. Absorbtion is what your digestive tract assembles from the food you eat. Which makes the rest of your question(s) obsolete. You cannot store 6-7g/h as muscle tissue - unfortunately. Take a look at the data in figure 2. That's what you can actually store (FSR = fractional protein synthesis in muscle)

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    2. Thanks a lot for clearing that up, i'm just getting started learning about athletic led nutrition, and sites like yours are a gold mine, although i end up hitting a ceiling of understanding quicker than i'd like sometimes! :)

      Thanks again.

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  8. The high glutamine and alanine content in said high quality proteins would be more than enough to fuel significant gluconeogenesis to keep the requirements for fat and carbohydrate far lower than stated here, at the same time, excess protein will still be oxidized, and taking into account that the Dietary energy expenditure of protein is about 150% higher than carbs and 800% higher than fats, would result in a less (or more depending on your viewpoint) favourable energy balance and greater satiety. While there is no need to go "low carb" or "low fat" (whatever started those fads), the benefits of "high protein" exceed simple contributions to FSR.

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  9. If 30 grams of protein needs to be taken in every meal, what about carbs ? Should we eat
    a) a certain amount of carbs in every meal (split our carbs to all meals),
    b) most, if not all of them, only after resistance training or
    c) take most of them at a certain time of day only e.g in breakfast ?

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    1. Since I annoy Adel with these kinds of questions all the time, let me attempt to answer one and hopefully spare him the task of doing so haha.

      a) the amount of carbs you eat per meal is totally dependent on your preferences and the number of meals. There is some science that suggests that "saving" your carbs for dinner and only eating fats earlier in the day (protein spaced evenly) is optimal. The Biorythm Diet by Borge Fagerli (http://www.reactivetrainingsystems.com/articles/nutrition/10480-the-biorhythm-diet) and carbohydrate back-loading are examples of this.

      b) It is definitely advantageous to eat MOST of your carbs post-workout (not immediately PWO, but in the feeding window that follows) because insulin sensitivity will be higher in the muscles and lead to better partitioning, not to mention you will have depleted glycogen and need replenishment.

      c) Coming off what I said in (b), this would most likely apply to "rest" days or days reserved for light cardio. In this case, we must refer back to (a). The idea of breakfast is literally breaking the fast from sleeping. It is not that its the first meal of the day, but that liver glycogen will be lower and partitioning effects lead to better usage of the carbs you eat. This comes full-circle to the idea of carb back-loading. By not "breaking the fast" with carbs, your body is forced to remain reliant on fats for energy, but since your brain can only use glucose or ketones for energy (and the later takes time to have any significant influence), your liver will still pump out its glycogen stores. By the time dinner roles around, you will be even more liver glycogen depleted and when you stuff your face with carbs, your body will shuttle them all away as glycogen. That's the bottom line anyway, read the biorythm diet in the link I posted above if you want the science part of it.

      Hope this helps!

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    2. Thank you for your reply, Primalkid !I appreciate your input in Suppversity and have learnt a lot from your comments. I will study the Biorythm diet and try it for a few weeks.

      I have to admit that the more I read results of studies in PubMed the more confused I get. Some mice studies show that carbs and especially fats should not be eaten in the end of the active period and the main portion of a day's meals should be taken during the beginning and early in the active period. That's why I am afraid to start eating carbs in the evenings (especially if I have not lifted weights that day). For some reason I crave for carbs in the mornings (porridge, yam yam) and the mere thought of eating meat and/or eggs in the mornings makes me feel sick. Maybe it is a question of habits or maybe it is my body telling me what it needs. Anyhow I will try the mentioned diet and find out if my body gets accustomed to it.

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    3. You have to remember that mice are not humans. More recent work has shown eating carbohydrates at dinner rather than breakfast is superior for weight loss and metabolic flexibility.

      That said, I more or less follow the biorythm diet TEMPLATE (not the actual diet, but some of the concepts from it) and I am on a bulking diet. I can say that "carb-loading" at dinner has helped keep me lean with consistent strength gains in the gym. But everyone is different, see how you respond.

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    4. you will also have to keep in mind that the total amount of carbs these poor rodents are fat is much higher (as it is by the way supposed to be for a rodent).

      I am also not yet sure if the statement that carbs at dinner would be GENERALLY better than at dinner is right - specifically outside of a diet scenario (=eating less than you need). If you diet it has the advantage that you will burn body fat during the day and help your metabolism not to crash by filling back up in the evening

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  10. are there any ways to calculate the amount of carbs needed on an individual basis? i've read several times that "about 100g" is a good starting point to avoid glucoegensis, but that seems arbitary, is there a calculation for someone to follow?

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    1. It really depends on personal goals and characteristics. Whether you are cutting or bulking, insulin sensitivity, training intensity, duration, etc.

      "In general, assuming zero or very low levels of activity, an intake of 100-120 grams of carbohydrates per day will prevent the development of ketosis, just providing the brain with enough carbohydrates to function ‘normally’. So, for folks who want (or need) to just avoid ketosis, 100-120 grams per day will act as a practical limit. Again, this won’t quite work as a recommendation for people involved in high-intensity activity since not all of the incoming carbs will be available for the brain." - Lyle McDonald "How Many Carbohydrates do you Need?" (http://www.bodyrecomposition.com/nutrition/how-many-carbohydrates-do-you-need.html)

      I highly recommend you read the article I quoted from. The site also has many other nutrition resources you may find helpful.

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    2. The BB article mention's that lifting requires neural demand. If lifting requires neural demand, does this mean even light weightlifting could impair cognitive function or mood? I don't see this as being likely but thought I should ask. I understand aerobic exercise is good for the brain, I would love to know if anaerobic is.

      You said that if I "learn to master the moves", I won't get GERD. What did you mean by this? It is vital that lifting weights doesn't aggravate my gerd, as I get pretty strong reflux.

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    3. neural demand has little to nothing to do with your ability to think - only if you are totally overtraining that will become hampered. So no problem with lifting.

      "master the moves" means - get a certified trainer and have him teach you how to do it (or ask someone you are watching at the gym, who does thing right to check your form) - I can tell you that by just looking in the mirror it's almost impossible to correct all mistakes you may be making. Most importantly don't hold your breath that's probably no1 in causing hernias and thus GERD

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  11. High-protein diet has been associated with depression. Dr. Andro, how should a bodybuilder suffering from depression form his diet ? Protein is needed to build muscle but very high protein and low carbohydrate meals prevent absorption of tryptophan because of the increased competition for transit between amino acids. What would be the ideal diet for those suffering from depression (who are plenty as depression seems to be a plague of modern society) ?

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  12. For building muscles it is better to eat slower protein sources (high in EAA) than faster?

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