Bustin Broscience - a new article series by the Appnuts

[EasyEJL]

Bustin Broscience
where rep points don't matter

The appnuts got together and dedcided we wanted to give some back to the community, and so we're starting a new regular feature called Bustin Broscience. We're going to take bits of common broscience and examine them, try to find scientific justifications to either support or contradict them. We'll present it to you in a clean easy to read format, giving you more tools to work with. I expect we'll all learn a few things we didn't know (or get scientific evidence for things we felt were true) over the course of this series of articles. Our first topic is "You can only absorb 25 grams of protein in one meal" by EasyEJL, Applied Nutriceuticals Rep.

[EasyEJL]

Its something I?m sure you?ve all heard before although the exact number used varies. ?You can only absorb ___ grams of protein in one meal,? with 25g being probably the most commonly used number. Like with many pieces of broscience, the real answer is a lot more complex. Lets start with the simplest part of this, ignoring bodybuilding entirely. For men, the USRDA for protein is .8g/kg. That equates to 72g of protein for a 200lb male. Divided into 3 meals, that would only come to 24g per meal, which falls inside the 25g per meal myth. But that of course is the minimum recommended, not a maximum absorbable.

From what I?ve seen, I believe the myth started with some of the early studies on egg protein absorption. For whatever reason, 25g is the commonly used amount for egg protein studies, which is the amount roughly in 3 jumbo eggs, or 4 large eggs. There are numerous studies done with the egg protein showing various amounts escaping digestion. A fair example is this one Amount and fate of egg protein escaping assimilation in the small intestine of humans -- Evenepoel et al. 277 (5): 935 -- AJP - Gastrointestinal and Liver Physiology . The important piece to keep in mind is that even in this case the protein absorption throughout the digestive tract occurs over a 72 hour period given the time it takes to pass through the intestines, with a total recovery of approx 5% of the protein leaving the body rather than being used. But even with egg?s high bioavailability and rapid absorption, you don?t see peak levels until 3 hours or so post intake.

With other protein forms such as milk based (casein, whey, etc), you have both different digestion rates, as well as different absorption rates. This study Compared with casein or total milk protein, digestion of milk soluble proteins is too rapid to sustain the anabolic postprandial amino acid requirement -- Lacroix et al. 84 (5): 1070 -- American Journal of Clinical Nutrition specifically was looking at milk based proteins. What is interesting for the sake of this myth is the figure 3 graph of changes to serum amino acids. The milk soluble protein isolate reached a peak serum BCAA level 3x higher than either casein or total milk protein within 1 hour and remained 2x as high through the second hour. It dropped back to below the level of the other proteins by 4 hours. This was based on approx 22g of protein in each of the types. The important point demonstrated is that amino acid levels are able to be elevated significantly higher than what 22g of casein will raise it in a single meal. Note that the total milk protein and casein both showed elevated BCAA levels out to 8 hours, and overall elevated amino acid levels to 7 hours, showing how long a single meal can take to travel through digestion.

A similar study The digestion rate of protein is an independent regulating factor of postprandial protein retention -- Dangin et al. 280 (2): E340 -- AJP - Endocrinology and Metabolism was done using free amino acids, whey, casein and repeated whey meals. These were done with 30g. Even with the free form amino acids, peak plasma concentration of leucine (remember, this is basically eating a spoonful of leucine) wasn?t until 60 minutes.

A compilation of protein studies is available as a separate study here http://www.humankinetics.com/eJourna.../pdfs/5642.pdf which gives some pretty specific numbers for protein absorption rates. Using caseins they show an approximate rate of 6g/hr, with whey at the top being 8-10g/hr. Using those as maximums per day, you can probably reach (in 3 meals) as much as 50g of casein, and still utilize it all. Whey on the other hand dose show the fast spike but relatively fast drop as well, so although there is a theoretical higher grams per hour its washout is also higher, requiring more frequent meals to maintain the absorption, so probably 25-30g as whey every 3 hours gets you optimal absorption.

So what does this all mean? Well, for starters its pretty obvious that with casein supplying aminos for as much as 9 hours post-meal and a max absorption in normal healthy individuals NOT weight training of around 6 grams per hour means that a meal as large as 54g of casein can be almost entirely absorbed. As far as fish, poultry or beef goes, there aren?t nearly as many studies done, and none that are so granular in terms of timing. Given that eggs have around a 3g/hr rate, and pea/soy go from 3-4g/hr that it is not at all unreasonable to assume that animal sources have somewhere in the range of 3-10g/hr.

The piece missing from any studies I could find which could make a significant difference is the addition of carbohydrates and/or fats. Is it possible that with the addition of fats or fiber that a larger amount of whey proteins can be taken in a meal, with overall movement of the protein from stomach to amino acids in bloodstream would be slowed down enough that the 10g per hour could be maintained for 5 or 6 hours keeping the 10g/hr bloodstream absorption? I think it is likely to be the case, and hope that someday we see some studies done with more real world scenarios than fasted whey only meals.

So is the myth busted? You bet, its definitely possible to take in as much as 50-60g of casein in a single serving, and use the vast majority of it, and that is for a non-weight training individual. With increased protein turnover in a bodybuilder, its likely that you can absorb even more. The other thing I learned as I researched this that may interest many of the rest of you is as below

?An important question then must be posed: ?Does a more rapidly absorbable protein result in greater in vivo protein synthesis?? This is a central issue of large protein consumption with fitness enthusiasts, athletes, and bodybuilders. Early findings suggest that rapidly absorbed proteins such as free amino acids and WP, transiently and moderately inhibit protein breakdown, yet stimulate protein synthesis by 68% [using nonoxidative leucine disposal (NOLD) as an index of protein synthesis]. Casein protein has been shown to inhibit protein breakdown by 30% for a 7-h postprandial period, and only slightly increase protein synthesis. 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. 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.?

A quickie summary of this is that although casein seems to only slightly increase protein synthesis, overall there is a better net protein gain than with faster absorbed proteins sich as whey, unless you feel like taking 3g of whey every 20 minutes. So I may be changing a bit more of what little I take in protein shakes now for more casein, or a mixed casein/whey source.

Broscience Busted - There is no particular evidence that 25, 30, 40 or even 50g is a maximum absorbable in a single meal, the type of protein has a lot more bearing. As much as 60 or 70g protein from casein could be taken in and still be used over the next 8 hours even in a non-weightlifting individual.

[EasyEJL]

Hope you enjoy that first article, there will be more in the series coming regularly in the future. Any comments, questions or suggestions feel free to let us know. It was interesting for me to research this, as i'm still a bit surprised as to how long even BCAAs or whey take to get to bloodstream (for all that people say they are fast), and how relatively rapidly casein gets there.

[RosieCheeScott]

Great start to the series

[LP36]

In on this!

[NO HYPE]

The average maximum absorption rate of whey protein has been observed at around 10 grams per-hour [and less for casein].

http://forum.bodybuilding.com/showpo...1&postcount=33

[Beejis60]

http://forum.bodybuilding.com/showpo...1&postcount=33

That's just whey though; what about meats, eggs, etc?

[NO HYPE]

That's just whey though; what about meats, eggs, etc?

Yeah, I wasn't arguing any aforementioned points.... just throwing this out there for the relevance.

[Outside backer]

glad to see you here No Hype I know you know your ****

[NO HYPE]

glad to see you here No Hype I know you know your ****

Do I have to load creatine?

[Cable Curling CincoUno]

Do I have to load creatine?

not if you spike insulin

[Beejis60]

not if you spike insulin

With 100g sugar, that is.

[EasyEJL]

Do I have to load creatine?

it has to get in the trucks somehow

[EasyEJL]

That's just whey though; what about meats, eggs, etc?

Nobody stands to make extra money off the bodybuilding industry by showing that beef digests over a longer period.... so less likely to see studies funded.

[NO HYPE]

Nobody stands to make extra money off the bodybuilding industry by showing that beef digests over a longer period.... so less likely to see studies funded.

Most supplement companies have nothing to do with the funding of scientific research.

[NO HYPE]

where rep points don't matter

Negged.

[RosieCheeScott]

Do I have to load creatine?

It's not necessary, but can be done to maximize the creatine within the muscle.

[DaveGabe24]

Great idea App Nuts...I think this will be a great place to link future newbs to

[rpen22]

That's just whey though; what about meats, eggs, etc?

Estimated intestinal absorption rates of different protein sources:
Raw egg protein-->1.4g/hr
Cooked egg protein-->2.9g/hr
Pea protein-->3.5g/hr
Milk protein-->3.5g/hr
Soy protein isolate-->3.9g/hr
Casein isolate-->6.1g/hr
Whey isolate-->8-10g/hr
Tenderloin pork steak-->10.0g/hr

*Stolen from The Protein Book by Lyle McDonald*

[Cable Curling CincoUno]

*Stolen from The Protein Book by Lyle McDonald*

blasphemy. even if I eat 60gs of protein from pork I still need to eat 2 hours later to keep a steady flow of aminoz or I will go catabolic immediately.

[rpen22]

blasphemy. even if I eat 60gs of protein from pork I still need to eat 2 hours later to keep a steady flow of aminoz or I will go catabolic immediately.

Thats where teh waxzy maize starch comes in. You need to spike teh insulin levelz to keep you anabolic.

[NO HYPE]

It's not necessary, but can be done to maximize the creatine within the muscle.

Oh hai there.

Thanks for the honest response [despite the fact that I was merely being a sarcastic ass].

A loading phase of 20g per-day, will saturate PCr values in about 5-6 days, while a dose of about 3g per-day takes about a month [1].

[1] Green A, Hultman E, Macdonald IA, et al. (1996). Carbohydrate ingestion augments skeletal muscle creatine accumulation during creatine supplementation in man. Am J Physiol 1996;271:E821-6.

Is there truly a need for daily creatine supplementation?

[NO HYPE]

glad to see you here No Hype I know you know your ****

Much appreciated OB.

[Black_Label]

I am finally here!

I remember worrying about this topic when i started lifting...

[Beejis60]

*Stolen from The Protein Book by Lyle McDonald*

That seems to be backward from the brologic around here; the eggs are supposed to be fast, blah blah. From where does Lyle get this info? I know it says estimated, but there has to be something that leads him to estimate this stuff.

[donorrell]

That seems to be backward from the brologic around here; the eggs are supposed to be fast, blah blah. From where does Lyle get this info? I know it says estimated, but there has to be something that leads him to estimate this stuff.

I agree. I'm particularly surprised by pork showing the highest absorption rate, which makes be suspect.

[Black_Label]

That seems to be backward from the brologic around here; the eggs are supposed to be fast, blah blah. From where does Lyle get this info? I know it says estimated, but there has to be something that leads him to estimate this stuff.

That chart seems misleading for many reason.

I can barely articulate my words to describe what i am thinking about it ><


If you ate 50 grams of both, as i learned your body can use more of the egg protein (90ish%) vs say beef (60ish%)

so in the end you have 45g egg and 30g beef. So the egg is absorbed slower, but you have more than beef.


I dont know, still is not adding up right

[leonidas300]

Where is Alan Arragon when you need him.

[rpen22]

That seems to be backward from the brologic around here; the eggs are supposed to be fast, blah blah. From where does Lyle get this info? I know it says estimated, but there has to be something that leads him to estimate this stuff.

He says that the two egg proteins and the pork numbers are "quite preliminary as some of the studies used fairly indirect measurements to estimate protein digestion rate". He goes on to say that those aren't taking into account GI adaptations to high protein in terms of gastric emptying and max transport capacity. "The more calories the athlete habitually consumes, the faster they digested their meals".

[Cable Curling CincoUno]

He says that the two egg proteins and the pork numbers are "quite preliminary as some of the studies used fairly indirect measurements to estimate protein digestion rate". He goes on to say that those aren't taking into account GI adaptations to high protein in terms of gastric emptying and max transport capacity. "The more calories the athlete habitually consumes, the faster they digested their meals".

Are there references he gives in the back? I don't have the Protein Book yet. He must, it's Lyle for christ's sake.

"The more calories the athlete habitually consumes, the faster they digested their meals"
-that part sort of surprised me. I thought it would of had more to do with the hypothalamus adapting to frequent feedings (6-8 meals vs 2-3 meals) than just calories consumed. I remember Dr. Houser describing it like this:

[1] Multiple small feedings q 2-3 hours ---> gastroneuronal communication senses consistent nutrient flow ---> increased GI transit to accomodate; allowance for greater metabolic efficiency

[2] Few feedings say q 6-8 hours (prototypical 3 square meals per day) ---> gastroneuronal communication senses pause in nutrient flow (essential "starvation mode" though this is an absolute terrible misnomer and one of my pet peeves when I see it referenced this way, because this isn't exactly what happens, but the true process is beyond the scope of this post) ---> decreased GI transit (slow progression through GI tract to allow for greater surface area contact with particulate manner for as best an absorption it can be offered, though highly inefficient.