Lots of people in bodybuilding subscribe to the 'more is better' philosophy for just about anything, protein included.

An intake of 1.5-2g/pound of bodyweight is not uncommon to see thrown around on many boards. And yet, there is pretty good data that your gut uptake, even of whey, is limited to about 10g/hour or so and is less than this for other proteins. Meaning that if you are consuming more than 250g of protein, you are flushing the excess down the crapper...

A Review of Issues of Dietary Protein Intake in Humans

Considerable debate has taken place over the safety and validity of increased protein intakes for both weight control and muscle synthesis. The advice to consume diets high in protein by some health professionals, media and popular diet books is given despite a lack of scientific data on the safety of increasing protein consumption. The key issues are the rate at which the gastrointestinal tract can absorb amino acids from dietary proteins (1.3 to 10 g/h) and the liver's capacity to deaminate proteins and produce urea for excretion of excess nitrogen. The accepted level of protein requirement of 0.8g ∙ kg-1 ∙ d-1 is based on structural requirements and ignores the use of protein for energy metabolism. High protein diets on the other hand advocate excessive levels of protein intake on the order of 200 to 400 g/d, which can equate to levels of approximately 5 g ∙ kg-1 ∙ d-1, which may exceed the liver?s capacity to convert excess nitrogen to urea. Dangers of excessive protein, defined as when protein constitutes > 35% of total energy intake, include hyperaminoacidemia, hyperammonemia, hyperinsulinemia nausea, diarrhea, and even death (the ?rabbit starvation syndrome?). The three different measures of defining protein intake, which should be viewed together are: absolute intake (g/d), intake related to body weight (g ∙ kg-1 ∙ d-1) and intake as a fraction of total energy (percent energy). A suggested maximum protein intake based on bodily needs, weight control evidence, and avoiding protein toxicity would be approximately of 25% of energy requirements at approximately 2 to 2.5 g ∙ kg-1 ∙ d-1, corresponding to 176 g protein per day for an 80 kg individual on a 12,000kJ/d diet. This is well below the theoretical maximum safe intake range for an 80 kg person (285 to 365 g/d).

Amino acid catabolism must occur in a way that does not elevate blood ammonia (26). Catabolism of amino acids occurs in the liver, which contains the urea cycle (26), however the rate of conversion of amino acid derived ammonia to urea is limited. Rudman et al. (27)

Early findings suggest that rapidly absorbed proteins such as free amino acids and WP, transiently and moderately inhibit protein breakdown (39, 53), yet stimulate protein synthesis by 68% [using nonoxidative leucine disposal (NOLD) as an index of protein synthesis] (54). Casein protein has been shown to inhibit protein breakdown by 30% for a 7-h postprandial period, and only slightly increase protein synthesis (38, 54). 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 (39, 54).

The misconception in the fitness and sports industries is that rapidly absorbed protein, such as WP and AA promote better protein anabolism. As the graph shows, slowly absorbed protein such as CAS and small amounts of WP (RPT-WP) provide four and nine times more protein synthesis than WP.

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 shown in Table 2 (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) (38), which corresponds to a maximal protein intake of 144 to 168 g/d.

The rate of amino acid absorption from protein is quite slow (~ 5 to 8 g/h, from Table 2) when compared to that of other macronutrients, with fatty acids at ~ 0.175 g ? kg-1 ? h-1 (~ 14 g/h) (55) and glucose 60 to 100 g/h (0.8 to 1.2 g carbohydrate ? kg-1 ? h-1) for an 80 kg individual (56). From our earlier calculations elucidating the maximal amounts of protein intake from MRUS, an 80 kg subject could theoretically tolerate up to 301 to 365 g of protein per day, but this would require an absorption rate of 12.5 to 15 g/h, an unlikely level given the results of the studies reported above.

The consumption of large amounts of protein by athletes and bodybuilders is not a new practice (13). Recent evidence suggests that increased protein intakes for endurance and strength-trained athletes can increase strength and recovery from exercise (14, 80, 81). In healthy adult men consuming small frequent meals providing protein at 2.5 g ? kg-1 ? d-1, there was a decreased protein breakdown, and increased protein synthesis of up to 63%, compared with intakes of 1g ? kg-1 ? d-1 (16). Subjects receiving 1g ? kg-1 ? d-1 underwent muscle protein breakdown with less evident changes in muscle protein synthesis. Some evidence suggests, however, that a high protein diet increases leucine oxidation (82, 83), while other data demonstrate that the slower digestion rate of protein (38, 54), and the timing of protein ingestion (with resistance training) (84) promote muscle protein synthesis.

Absorption rates of amino acids from the gut can vary from 1.4 g/h for raw egg white to 8 to 10 g/h for whey protein isolate. Slowly absorbed amino acids such as casein (~ 6 g/h) and repeated small doses of whey protein (2.9 g per 20 min, totaling ~ 7 g/h) promote leucine balance, a marker of protein balance, superior to that of a single dose of 30 g of whey protein or free amino acids which are both rapidly absorbed (8 to 10 g/h), and enhance amino acid oxidation. This gives us an initial understanding that although higher protein intakes are physiologically possible, and tolerable by the human body, they may not be functionally optimal in terms of building and preserving body protein. The general, although incorrect consensus among athletes and bodybuilders, is that rapid protein absorption corresponds to greater muscle building.

From the limited data available on amino acid absorption rates, and the physiological parameters of urea synthesis, the maximal safe protein intakes for humans have been estimated at ~ 285 g/d for an 80 kg male. It is not the intention of this article, however, to promote the consumption of large amounts of protein, but rather to prompt an investigation into what are the parameters of human amino acid kinetics. In the face of the rising tide of obesity in the Western world where energy consumption overrides energy expenditure, a more prudent and practical approach, which may still provide favorable outcomes, is a 25% protein energy diet, which would provide 118 g protein on an 8000 kJ/d diet at 1.5 g ? kg-1 ? d-1 for an 80 kg individual (Table 2).

Little data exists on the comprehensive metabolic effects of large amounts of dietary protein in the order of 300 to 400 g/d. Intakes of this magnitude would result in some degree of prolonged hyperaminoacidemia, hyperammonemia, hyperinsulinemia, and hyperglucagonemia, and some conversion to fat, but the metabolic and physiological consequences of such states are currently unknown. The upper limit of protein intake is widely debated, with many experts advocating levels up to 2.0 g ? kg-1 ? d-1 being quite safe (102, 117, 118) and that renal considerations are not an issue at this level in individuals with normal renal function.

Original source

Very interesting.

195g counting all sources at around 150--jus' sayin.

good read Benson, but I hate looking at kilojoules, I can take the kilograms, but kilojoules...bleh

for everyone else's use:

the 12,000 kJ diet comes out to about 2868kcal
the 8,000 kJ comes out to about 1912kcal

Edit: God do I ever bitch, that was barely even pertinent

Can you fix the link? Not working...

http://www.humankinetics.com/eJournalMedia/pdfs/5642.pdf

Firstly, great find Ben, this is a good read.

Secondly, is anyone that surprised with this? I've been advocating less is more for a while now in my personal interactions, particularly among endos. To much excess-related lore in the BB world has created too many fat BBers.

I take in about 250-270g, I'm on the anabolic diet so my protein intake is pretty high especially only being 160lbs.

The misnomer that you need more protein or you'll waste away is a great way to justify eating more, and sabotage a diet.

That said, protein is a less efficient fuel than carbs. Eating more protein isn't necessarily good because you need more protein, but because it can displace carbs, which can make staying lean (and healthy, as Benson pointed out in a thread citing research about the health benefits of lower carb diets) easier.

Exactly.

lets say you were to eat only protein, no fat no carbs, wouldn't your body turn protein into a carbohydrate?

Yes.

blah, didn't read it all, but if absorption is limited, then consumption is therefore also self-limiting, making it impossible to eat too much.

and as for rabbit starvation, i thought it had to do with a lack of fat in rabbit flesh, not an overconsumption of protein. who will die faster, a fat man on a fast, or a fat man eating only rabbit muscle? is he really going to suffer 'rabbit starvation' before he burns off all his own fat reserves?

Looks like getting high might slow things down a little -- maybe a positive thing, WRT the comments on small bits of whey over time being better than a bolus dose, which increased oxidation a bunch...

Damn high fat rat studies...
The role of endocannabinoids in the regulation of gastric emptying: alterations in mice fed a high-fat diet.
Di Marzo V, Capasso R, Matias I, Aviello G, Petrosino S, Borrelli F, Romano B, Orlando P, Capasso F, Izzo AA.

1Endocannabinoid Research Group, Institute of Biomolecular Chemistry, National Research Council, Pozzuoli, Naples, Italy.

Background and purpose:Endocannabinoids (via cannabinoid CB(1) receptor activation) are physiological regulators of intestinal motility and food intake. However, their role in the regulation of gastric emptying is largely unexplored. The purpose of the present study was to investigate the involvement of the endocannabinoid system in the regulation of gastric emptying in mice fed either a standard diet (STD) or a high-fat diet (HFD) for 14 weeks.Experimental approach:Gastric emptying was evaluated by measuring the amount of phenol red recovered in the stomach after oral challenge; CB(1) expression was analysed by quantitative reverse transcription-PCR; endocannabinoid (anandamide and 2-arachidonoyl glycerol) levels were measured by liquid chromatography-mass spectrometry.Key results:Gastric emptying was reduced by anandamide, an effect counteracted by the CB(1) receptor antagonist rimonabant, but not by the CB(2) receptor antagonist SR144528 or by the transient receptor potential vanilloid type 1 (TRPV1) antagonist 5'-iodoresiniferatoxin. The fatty acid amide hydrolase (FAAH) inhibitor N-arachidonoyl-5-hydroxytryptamine (but not the anandamide uptake inhibitor OMDM-2) reduced gastric emptying in a way partly reduced by rimonabant. Compared to STD mice, HFD mice exhibited significantly higher body weight and fasting glucose levels, delayed gastric emptying and lower anandamide and CB(1) mRNA levels. N-arachidonoylserotonin (but not rimonabant) affected gastric emptying more efficaciously in HFD than STD mice.Conclusions and implications:Gastric emptying is physiologically regulated by the endocannabinoid system, which is downregulated following a HFD leading to overweight.British Journal of Pharmacology advance online publication, 28 January 2008; doi:10.1038/sj.bjp.0707682.

PMID: 18223666 [PubMed - as supplied by publisher]

Edited to fix double post

interesting data on the absorption rates, that's 'useful' to know.

I also found this part to be interesting as well:

I'm 6'3" 260lbs, at 16% bodyfat. I train primarily for strength with a secondary bodybuilding emphasis. I have competed in strongman, and play rugby therefore I have a significant cardio component to my training.

I usually eat around 150gm protein when either growing or dieting. I used to prescribe to the 'more is better' mentality of protein but all that got me was a depleted wallet (from buying so much chicken).

I notice no difference in my recovery, my strength gain, or my bodycomp between 150gm protein/day and 300gm protein/day. Perhaps AAS are a factor.

I have found that a combination of whey + whole milk works very nicely....and it makes shakes taste awesome

If you're eating 6 times a day, which most of us do, you'll have continued anabolism whether you choose whey or casein.
IE./If you were eating one meal post workout and not another one again 3 hours later then of course casein would be better, but the spike of AAs delivered by whey has to be beneficial immediately post workout as long as you follow up with another meal 3 hours later.

I would choose whey post workout, and casein pre-bed.

But generally speaking, I believe the primary reason for whey being more popular is due to the powders of whey being more palatable than caseins d/t the thick texture and limited mixability.

my only grumble about this way of thinking is you have to replace the calories from somewhere. Many people's metabolisms don't deal with CHO very well. No matter what form of CHO I eat I will gain weight on it. Period. And not the good kind. If I keep CHO cyclic as I do now and keep fats low-moderate and protein a little higher I am able to eat more (volume wise) per day and stay leaner.

I go one better....I use 8oz of Hood Calorie Countdown milk...creamy shakes and minimal carbs...

unfortunately, then I would have to add some lactaid

Maybe not...the carbs they get rid of must mostly be in the form of lactose so you may find that Calorie Countdown milk doesn't bother you too much.

I don't see the Hood Calorie Countdown milk much any more.

I'll have to give it a try, as it is cheaper than lactose free milk...Mixing it with WP that has Aminogen helps

Well-chewed meat is a fast acting protein.

This may explain how I can eat two lbs of it and be hungry 3 hours later!

From bodyrecomposition.com:

Postprandial whole-body protein metabolism after a meat meal is influenced by chewing efficiency in elderly subjects1,2,3

Didier Rémond, Marie Machebeuf, Claude Yven, Caroline Buffière, Laurence Mioche, Laurent Mosoni and Philippe Patureau Mirand
1 From the Institut National de la Recherche Agronomique, UMR 1019, Unité de Nutrition Humaine, Centre de Clermont-Ferrand-Theix, Saint Genès-Champanelle, France


Background: The rate of protein digestion affects protein utilization in elderly subjects. Although meat is a widely consumed protein source, little is known of its digestion rate and how it can be affected by the chewing capacity of elderly subjects.

Objectives: We used a [1-13C]leucine balance with a single-meal protocol to assess the absorption rate of meat protein and to estimate the utilization of meat protein in elderly subjects with different chewing efficiency.

Design: Twenty elderly volunteers aged 60–75 y were involved in the study. Ten of them had healthy natural dentition, and the other 10 were edentulous and wore complete dentures. Whole-body fluxes of leucine, before and after the meal (120 g beef meat), were measured with the use of a [1-13C]leucine intravenous infusion.

Results: A rapid increase in plasma aminoacidemia and plasma leucine entry rate was observed after meat intake in dentate subjects. In complete denture wearers the increase in leucine entry rate was delayed (P < 0.05), and the amount of leucine appearing in peripheral blood during the whole postprandial period was lower than in dentate subjects (P < 0.01). Postprandial whole-body protein synthesis was lower in denture wearers than in dentate subjects (30% compared with 48% of leucine intake, respectively; P < 0.05).

Conclusion: Meat proteins could be classified as fast digested proteins. However, this property depends on the chewing capacity of elderly subjects. This study showed that meat protein utilization for protein synthesis can be impaired by a decrease in the chewing efficiency of elderly subjects.

Maybe you should try some Bass

You were close, turns out cod is the answer

Whereas whey, milk, and to some extent cheese ingestion
resulted in obvious amino acid responses, the remaining meals
(GH, GL, cod, and WWB) resulted in only small increases in
plasma amino acids. Generally, the amino acid responses to the
cod meal occurred 60 min after ingestion. In contrast, peak amino
acid responses to milk, whey, and cheese occurred more rapidly—
within 30–45 min after ingestion—which indicated that
milk proteins are highly digestible and result in a rapid release of
amino acids into the circulation

Although whey and cod proteins are similar with respect to the
content and distribution of amino acids, the postprandial plasma
pattern of amino acids differed substantially after the test meals
containing these proteins, most probably because of the different
digestion and absorption rates of these proteins. It is especially
interesting that several of the known insulinotropic amino acids
(leucine, valine, isoleucine, lysine,andthreonine)wereamongthose
amino acids that were observed to increase after the whey meal.

The free full-text is online

Glycemia and insulinemia in healthy subjects after lactoseequivalent
meals of milk and other food proteins: the role of plasma
amino acids and incretins1–3

So, here's another one...

Either

This 10 g/hr amino acid absorption rate can be affected by things like androgens or the PWO "window of opportunity"


Or

All the gearheads that preach about the body's increased "capacity to use protein" while on cycle are retarded, and they are misunderstanding
the rate-limiting step here.

Probably the latter, but you forgot to post the research!

EDIT: Just saw your edit

BUMP on androgens/PWO window and increased AA absorption kinetics? Otherwise why would whey hydrosylate be superior to slower PRO in the PWO window in trained individual (yall know the study)...

AND --

Consider the combination of this thread and the low-carb threads we have going currently.

Fat slows gastric emptying... so using a whey shake as an example (~24 g fast PRO), can we find the approximate amount of fat that could approximate the "2.3 g every 20 minutes" absorption rate that the RPT-WP method found superior? Whey + DAG at that ratio could be killer -- not sure if this ratio should be altered pre or PWO though.

As an aside, does anyone else wonder if these absorption kinetics match fairly well to the gastric release rate of a meat+fat meal (perhaps a common meal for evolutionary ancestors?)

If only ~10g of protein and ~15g of fat can be absorbed per hour, does that not set a daily limit of about 240g and 360g, respectively?

If it does then that's a maximum of 4300 cals per day that could be absorbed from those macronutrients, right?

In theory, yes. YMMV.

I eat 420g a day.

Do I win?

If its 420g of CHO, you sure do!

Bump.

BUMP on androgens/PWO window and increased AA absorption kinetics? Otherwise why would whey hydrosylate be superior to slower PRO in the PWO window in trained individual (yall know the study)...

-----------------------------------

I had posted this one in the IF thread:

Am J Physiol Regul Integr Comp Physiol. 2007 Nov 21; [Epub ahead of print]
Resistance training alters the response of fed-state mixed muscle protein synthesis in young men.
Tang JE, Perco JG, Moore DR, Wilkinson SB, Phillips SM.
Kinesiology, McMaster University, Hamilton, Canada.

Ten healthy young men (21.0 +/- 1.5 yr, 1.79 +/- 0.1 m, 82.7 +/- 14.7 kg, mean +/- SD) participated in eight weeks of intense unilateral resistance training (knee extension exercise) such that one leg was trained (T) and the other acted as an untrained (UT) control. After the eight weeks of training, infusions of L-[ring-d5] phenylalanine, L-[ring-(13)C6] phenylalanine, and d3 alpha-KIC were used to measure mixed muscle protein synthesis in the T and UT legs by the direct incorporation method (FSR). Protein synthesis was determined at rest, 4 and 28 h after an acute bout of resistance exercise performed at the same intensity relative to the gain in strength before and after training. Training increased mean muscle fibre cross-sectional area only in the T leg (type I: 16 +/- 10 %; type II: 20 +/- 19 %, P < 0.05). Muscle protein FSR in both legs at 4 h (T: 162 +/- 76 %; UT: 108 +/- 62 %, P < 0.01 versus rest) with the increase in the T leg being significantly higher than in the UT leg at this time (P < 0.01). At 28 h post-exercise, FSR in the T leg had returned to resting levels; however, the rate of protein synthesis in the UT leg remained elevated above resting (70 +/- 49%, P < 0.01). We conclude that resistance training attenuates the protein synthetic response to acute resistance exercise, despite higher initial increases in FSR, by shortening the duration for which protein synthesis is elevated. Key words: hypertrophy, feeding, weightlifting.

It would be nice to know what happens btw 4 and 28 hours. i.e. at what time does protein synthesis actually stops in the trained muslce?

This one is yours from the "post-exercise carbs a waste" thread:

Short-term insulin and nutritional energy provision do not stimulate muscle protein synthesis if blood amino acid availability decreases.
Bell JA, Fujita S, Volpi E, Cadenas JG, Rasmussen BB.

Sealy Center on Aging & Stark Diabetes Center, Department of Physical Therapy, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555-1144, USA.

Muscle protein synthesis requires energy and amino acids to proceed and can be stimulated by insulin under certain circumstances. We hypothesized that short-term provision of insulin and nutritional energy would stimulate muscle protein synthesis in healthy subjects only if amino acid availability did not decrease. Using stable isotope techniques, we compared the effects on muscle phenylalanine kinetics across the leg of an amino acid-lowering, high-energy (HE, n = 6, 162 +/- 20 kcal/h) hyperglycemic hyperlipidemic hyperinsulinemic clamp with systemic insulin infusion to a low-energy (LE, n = 6, 35 +/- 3 kcal/h, P < 0.05 vs. HE) euglycemic hyperinsulinemic clamp with local insulin infusion in the femoral artery. Basal blood phenylalanine concentrations and phenylalanine net balance, muscle protein breakdown, and synthesis (nmol.min(-1).100 g leg muscle(-1)) were not different between groups. During insulin infusion, femoral insulinemia increased to a similar extent between groups and blood phenylalanine concentration decreased 27 +/- 3% in the HE group but only 9 +/- 2% in the LE group (P < 0.01 HE vs. LE). Phenylalanine net balance increased in both groups, but the change was greater (P < 0.05) in the LE group. Muscle protein breakdown decreased in the HE group (58 +/- 12 to 35 +/- 7 nmol.min(-1).100 g leg muscle(-1)) and did not change in the LE group. Muscle protein synthesis was unchanged in the HE group (39 +/- 6 to 30 +/- 7 nmol.min(-1).100 g leg muscle(-1)) and increased (P < 0.05) in the LE group (41 +/- 9 to 114 +/- 26 nmol.min(-1).100 g leg muscle(-1)). We conclude that amino acid availability is an important factor in the regulation of muscle protein synthesis in response to insulin, as decreased blood amino acid concentrations override the positive effect of insulin on muscle protein synthesis even if excess energy is provided.

Taken together, a need for very rapid AA availability is suggested. [Given a 4-hour window, seems whey would be fast enough though.]

Contrast this, however, with the study showing whole milk to be more effective than skim PWO: http://www.mindandmuscle.net/forum/index.p...st&p=449315 .

And then this one ( http://www.mindandmuscle.net/forum/index.p...st&p=449402 ) suggesting that total milk protein is better than casein is better than whey (i.e. the slower the better).

Note the two milk studies were conducted with 'volunteers,' rather than trained individuals. That may make all the difference.

-----------------------------------

As an aside, does anyone else wonder if these absorption kinetics match fairly well to the gastric release rate of a meat+fat meal (perhaps a common meal for evolutionary ancestors?)

I posted a study in the first page of this thread suggesting that well-chewed meat is a fast-acting protein.

Well, we know about PRO synthesis being upregulated, we know that the AA pool size is critical and can be rate limiting, but my question still remains:

Is amino acid absorption (from the gut) altered PWO or with androgen use? Or does the 10g/hr stated in the OP still hold true?

And post workout, in trained individuals, I thought the faster the better (indicating altered absorption perhaps? -- I can't find the study ATM, I have it at home though so I'll post it later).

EDIT: And that study just says "fast protein" without including any numbers -- do you have the FT? Can we get numbers so as to compare with whey/casein/isolates/hydrolysates?

Abstract from study Dash sent is below.

The subjects added 0.68 g/lb of hydro-whey or casein, but only increased their total intake from about 0.8 g/lb to .95 g/lb. So whole food protein were replaced with supplements, and intakes remained low by body building standards. The hydro-whey group had better lean mass and strength gains, and dropped body fat.

From trueprotein.com: casein has 0.016 g Cystine/gram, hydro-whey high grade has 0.056g/g, and hydro-whey ultra grade has 0.1g/g. Whey is also higher in essential aminos than casein.

With ~70% of the protein intake coming from a supplement during the study, the above cannot be overlooked.

All we can really conclude is that replacing a large portion of whole food protein with hydro-whey is better than replacement with casein.

Would additional whole food protein have had the same effect?

--------------------------------------------------------------

THE EFFECT OF WHEY ISOLATE AND RESISTANCE TRAINING ON STRENGTH, BODY COMPOSITION AND PLASMA GLUTAMINE

It is well established that athletes undertaking intense resistance training programs require higher dietary protein intakes. However very few studies have addressed what type of protein is optimal to enhance stength gains from weight training exercise.

PURPOSE:
This study examined the effects of two commonly used dietary protein supplements, whey isolate and casein, on strength, body composition and plasma glutamine levels during a 10-week intense resistance training program.

METHODS:
In a randomized, double-blind protocol thirteen resistance-trained males (age: 25.5 ± 2.7, 26.1 ± 2.1 yrs; weight: 84.0 ± 2.0, 79.7 ± 4.2 mean ± SEM for whey (n = 6) and casein (n = 7) groups, respectively) supplemented their normal diet with either a 100% whey isolate or casein (1.5gms/kg body wt/day) for 10 weeks. All subjects undertook the same fully supervised resistance training program three days per week. Written three-day food recordings were completed by the bodybuilders to demonstrate that subject's normal eating patterns were maintained throughout the study. Strength was assessed by 1-RM in the barbell bench press, squat and pull down. Body composition was assessed by DEXA (QDR4500). Plasma glutamine levels were determined by an enzymatic method with spectroscopic detection. All assessments occurred in the week prior, to and the week following training.

RESULTS:
The whey isolate group achieved a significantly greater gain (P < 0.01) in lean mass (4.99 ± 0.25) than the casein group (0.81 ± 0.43kg). While both groups significantly increased (P < 0.05) strength in the three exercises assessed, the whey isolate group made greater strength increases (P < 0.05) in all three exercises compared to the casein group. The whey isolate group also showed a significant decrease (P < 0.05) in fat mass (-1.46 ± 0.52kg), whereas the casein group exhibited a slight rise (0.19 ± 0.27kg). Plasma glutamine levels, pre and post training, did not change in either group.

CONCLUSION:
The major finding of this study was that a 100% whey isolate protein supplement was more effective at increasing muscle mass and strength and decreasing fat mass than a casein protein supplement in resistance trained athletes. Both types of protein appear to prevent a decline in plasma glutamine levels that have previously been reported with intense exercise training. Supported by AST Sports Science.

fiber.

Don't forget, that the study above was in recreational bodybuilders -- much more applicable to our type of people than the average study.

True, but I wish they would do one of these studies right for a change.

For purposes of complete-ness: the 0.68 g/lb of protein supplement was divided breakfast, lunch, dinner, and PWO. Missed that on the first read through.

---------------

Elapsed time between feeding and appearance of leucine/aminos in serum would be a fair measure of rate of intestinal absorption, right? There's data on this, but apparently no direct measure of intestinal transport of aminos.

(From the last study we have hydro-whey beating out casein.)

All this has led me right back to where I started - that a mix of slow and fast proteins are best both after training and at rest. Whether it's casein + whey or casein + hydro-whey, don't see it making much of a difference.

I could not find leucine appearance data following a workout in trained subjects, but the study from Strength and Conditioning Research makes it a moot point.

------------------------------------------

Data on appearance of Leucine without prior workout below. Data on leucine appearance after training was not found.

Whey increases protein synthesis; casein decreases breakdown.

Young subjects ingest 30g whey or 40g casein after 10 hour fast, no workout beforehand although normal exercise and diet was maintained in days before the study.

Casein with 382 micro-mol leucine per kg

Leucine elevated 77%+-24% @ 100 minutes and 61%+-30% at 300 minutes

Whey with 380 micro-mol leucine per kg

Leucine elevated 236% +- 56% at 100 minutes and 29%+-11%

-----------------------

Slow and fast dietary proteins differently modulate postprandial protein accretion
Proc. Natl. Acad. Sci. USA Vol. 94, pp. 14930–14935, December 1997

Postprandial amino acid increases over baseline were identical whether the proteins were labeled or not. Those increases were different between CAS and WP (Table 2). The two protein meals were matched for leucine content but were not isonitrogenous, and amino acid intake was higher with CAS. Despite this higher amino acid intake, amino acid concentrations increased less with CAS than with WP at 100 min. By contrast, at 300 min, most amino acids remained at higher concentrations with CAS whereas they returned to basal levels with WP. These two particular plasma amino acid profiles also are illustrated by leucine concentration determined at each time point in Fig. 2A.

Plasma insulin levels similarly increased after both meals. The values were, at 0, 40, and 300 min, 6.2 6 2.4, 16.8 6 12.8, and 6.3 6 3.4 microU/ml, and 7.5 6 1.3, 19.8 6 5.3, and 6.1 6 1.4 microU/ml for CAS and WP, respectively. Note: In the whey group, protein breakdown still occurs even when insulin is elevated.)

Total NOLD (i.e., total protein synthesis) was stimulated by 68% and 31% (average from 40 to 140 min) with WP and CAS, respectively, the difference between the two diets being not significant although there was a trend for a higher protein synthesis with WP.

Under the conditions of this study, i.e., a single protein meal with no energy added, two dietary proteins have different metabolic fates and uses. After WP ingestion, the plasma appearance of dietary amino acids is fast, high, and transient. This amino acid pattern is associated with an increased protein synthesis and oxidation and no change in protein breakdown. By contrast, the plasma appearance of dietary amino acids after a CAS meal is slower, lower, and prolonged with a different whole body metabolic response: Protein synthesis slightly increases, oxidation is moderately stimulated, but protein breakdown is markedly inhibited. The latter metabolic profile results in a better leucine balance.

In the next study, whey + casein beats out whey, even when BCAAs and glutamine are added to the whey. Now, there's no data on casein + whey vs. hydro-whey or vs casein + hydro-whey. Think it's safe to assume that if mix of fast and slow is best, casein and hydro-whey would be better than hydro-whey alone.

Journal of Strength and Conditioning Research, 2006, 20(3), 643–653 _ 2006 National Strength & Conditioning Association

THE EFFECTS OF PROTEIN AND AMINO ACID SUPPLEMENTA ION ON PERFORMANCE AND TRAINING ADAPTATIONS DURING TEN WEEKS OF RESISTANCE TRAINING

ABSTRACT. The purpose of this study was to examine the effects of whey protein supplementation on body composition, muscular strength, muscular endurance, and anaerobic capacity during 10 weeks of resistance training. Thirty-six resistance-
trained males (31.0 _ 8.0 years, 179.1 _ 8.0 cm, 84.0 _ 12.9 kg, 17.8 _ 6.6%) followed a 4 days-per-week split body part resistance training program for 10 weeks. Three groups of supplements were randomly assigned, prior to the beginning of the exercise program, in a double-blind manner to all subjects: 48 g per day carbohydrate placebo (P), 40 of whey protein and 8 g/day of casein (WC), or 40 g/d of whey protein, 3 g/day branched-chain amino acids, and 5 g/day L-glutamine (WBG). At 0, 5, and 10 weeks, subjects were tested for fasting blood samples, body mass, body composition using dual-energy x-ray absorptiometry (DEXA), 1 repetition maximum (1RM) bench and leg press, 80% 1RM maximal repetitions to fatigue for bench press and leg press, and 30-second Wingate anaerobic capacity tests. No changes ( p _ 0.05) were noted in all groups for energy intake, training volume, blood parameters, and anaerobic capacity. WC experienced the greatest increases in DEXA lean mass (P _ 0.0 _ 0.9; WC _ 1.9 _ 0.6; WBG _ _0.1 _ 0.3 kg, p _ 0.05) and DEXA fat-free mass (P _ 0.1 _ 1.0; WC _ 1.8 _ 0.6; WBG _ _0.1 _ 0.2 kg, p _ 0.05). Significant increases in 1RM bench press and leg press were observed in all groups after 10 weeks. In this study, the combination of whey and casein protein promoted the greatest increases in fat-free mass after 10 weeks of heavy resistance training. Athletes, coaches, and nutritionists can use these findings to increase fat-free mass and to improve body composition during resistance training.



If anyone has data on casein + whey vs. casein + hydro-whey, that would seal the deal.

Perhaps. Imagine a transport mechanism for certain aminos (for example) that acted quickly, but was easily saturated. In this case, time would be a poor indicator, because although the appearance might be near instantaneous, if the system is saturated at 1g/hr, it's not doing much.

Different aminos will have different absorption kinetics, I would assume (not sure about intestinal, but for example intracellular BCAAs are transported by system L don't seem to have any factors that increase the rate of transport, whereas other transport mechanisms for other aminos use a Na+ antiport system that can be manipulated I assume).

Looking at the graphs for leucine appearance after meat, whey, and casein ingestion - meat spikes leucine like whey for the first two hours but keeps leucine elevated for four hours like casein does. i.e. meat mimics a mix of casein and whey.

I am reminded of the study concluding that milk is as effective as casein + whey. Might the same be seen with beef?

Damn, I might have saved myself an hour or so of research.

Well, absoption kinetics and transporters should make for interesting reading ... at a later date. Lost is coming on soon - brain is turning off.

you are forgetting something - digestion issues (esp. post workout)

Posted this in the wrong thread last night

Casein + whey for the win! (On basis of taste and price over hydro-whey)

No difference between intestinal absorption speed of hydro-whey vs. whey.

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Gastric emptying, gastric secretion and enterogastrone response after administration of milk proteins or their peptide hydrolysates in humans

Abstract:
The influence of protein fractionation on gastric emptying and rate of appearance of their constituent amino acids in peripheral blood remains unknown.

To examine the influence of the degree of protein fractionation on gastric emptying, gastric secretion, amino acid absorption and enterogastrone response, after the intragastric administration of complete cow milk proteins or their respective peptide hydrolysates in man.

Six healthy males were randomized to receive one of the following four solutions: whey whole protein (W), casein whole protein ©, whey peptide hydrolysate (WHY) or casein hydrolysate (CAHY). All solutions were matched for volume (600 mL), nitrogen content (9.3 g/L), energy density (1069–1092 kJ/L), osmolality (288–306 mosmol/kg), pH (6.9–7.0) and temperature (37 °C).

Solutions were emptied at similar rates, with mean half-times of (mean ± SEM) 21.4 ± 1.3, 19.3 ± 2.2, 18.0 ± 2.5 and 19.4 ± 2.8 min, for the WHY, CAHY, C and W, respectively. The rates of intestinal absorption of water and amino acids were similar with the exception of the casein protein solution, for which the speed of intestinal amino acid absorption was slower (p < 0.05). The peptide hydrolysates elicited about 50% more gastric secretion than the whole protein solutions (p < 0.05),which was accompanied by higher glucosedependent insulinotropic polipeptide (GIP) plasma levels during the first 20 min of the gastric emptying process. Similar glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) plasma responses were elicited by the four solutions.

The rate of gastric emptying and the plasma GLP-1 and PYY responses to feeding with cow milk protein solutions in humans are independent of the degree of protein fractionation and are not altered by small differences in the amino acid composition or protein solubility. In contrast, the GIP response is accentuated when milk proteins are delivered as peptide hydrolysates.

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In The Protein Book, Lyle suggests that, barring mass consumption of a single amino acid, transporter saturation/competition is unlikely. Also, intestinal absorption rates are given for a few protein sources: (in g/hr)

Cooked egg 2.9
Milk protein 3.5
Casein 6.1
Whey isolate 8-10
Pork tenderloin 10 (!)

Finally, references suggesting that high protein consumption will lead to faster digestion and absorption over time are given.

Very nice -- I like!

?? As in SNS stops gastric motility? Isn't this avoided by ingesting free aminos, which can be absorbed directly?



In the big picture, is this good? Referring to the OP's suggestion that fast PROs also switch on increased oxidation, resulting in a lower overall N balance?

Fast PRO is great PWO, when we have that small window in trained individuals, but at other times we want casein-type stuff, right?