T Nation

Surprising Protein Absorption Rates


The charts show that the absorption rates of casein, whey and their hydrolysates are not as dramatically different as we are often led to believe. What do you reckon?

Do you have an original source? That seems pretty interesting (after squinting for 10 minutes)

From the looks of it there isn’t much of a difference between regular and hydrolyzed whey, but the hydrolyzed casein does show a somewhat larger and more rapid increase initially. I would say though, that perhaps, as judged from these data, it would be more cost-effective to simply use a larger dose of regular whey to achieve the same response.

In any case, it’s something to think about.

This could also function as an eyesight test.

9 g/L of protein was used. That sucks.

[quote]WestCoast7 wrote:
This could also function as an eyesight test.[/quote]

lol!

[quote]silverhydra wrote:
Do you have an original source? That seems pretty interesting (after squinting for 10 minutes)[/quote]

Eur J Nutr. 2004 Jun;43(3):127-39. Epub 2004 Jan 6. Links
Gastric emptying, gastric secretion and enterogastrone response after administration of milk proteins or their peptide hydrolysates in humans.

Calbet JA, Holst JJ.
Copenhagen Muscle Research Center, Rigshospitalet, Copenhagen, Denmark. lopezcalbet@terra.es

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

AIM OF THE STUDY: 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.

METHODS: 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 degrees C).

RESULTS: 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 glucose-dependent 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.

CONCLUSIONS: 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.

[quote]WestCoast7 wrote:
This could also function as an eyesight test.[/quote]

it’s not so bad if you click on the pic to enlarge

[quote]BulletproofTiger wrote:
9 g/L of protein was used. That sucks.[/quote]

the 9g is nitrogen content per litre not protein

On most computers you can hold the control key and scroll the mouse wheel to kind of zoom/unzoom. Hope this helps somone

[quote]Rich Hand wrote:
BulletproofTiger wrote:
9 g/L of protein was used. That sucks.

the 9g is nitrogen content per litre not protein

[/quote]

Right - They’re using 38-39 grams of protein if my math is correct… (1069kJ*.6)/4.186calories/kJ =153.25 calories; 153.25 calories/4 grams of protein per calorie = ~38

The results are pretty odd indeed. The graphs do show that the hydros are up-taken more rapidly, but not by much.

This would surely make protein timing less significant.

It was 36 grams. Maybe this is enough to reach a an absorbtion max, regardless of protein type? Remember that these subjects were fasting and had their stomachs pumped beforehand, meaning that everything would flow quite rapidly through, especially a non-viscous liquid like a shake.

This blows me away, especially that casein appears to clear the gut so quickly (although to be fair the stomach was pumped, etc, so you have to consider that the body was more efficient at speeding protein through the digestive tract. Even so, the fast that the differences are so minor is astonishing. From the graph, it shows ~2,500 TAA (total amino acids) a the baseline amount. Is this a normal amount? If so, it looks like it takes a little over 2 hours you are near baseline.

I’ve often asked this question to sales reps for years. I wanted to know in terms of minutes post workout what the difference REALLY was given the whole anabolic window of opportunity. They could never really answer me so this is good to see. I always thought micro managing protein types wasn’t as high a priority that everyone makes it out to be. There are more important variables to worry about.

Right, so the whole benefit of hydros is that they show a spike at about 20 minutes, whereas the others just sort of reach a max and slowly level off. They all seem to reach around the same absorptivity though besides that. So, all it comes down to is that spike at 20 minutes.

Makes me wonder why consuming whey protein shakes all day doesn’t lead to the positive gains other foods and casein do when they apparently have a similar absorption rate.