Protein?

[Deadgame]

Ok the human body, so I have heard can only absorb between 20 to 25 grams of protein.

So if you eat a steak that has 100 grams of protein does this mean your only going to absorb around the 20 to 25 gram mark?

In other words do you have to take in a large amount of protein the get the target 20 to 25 gram mark?

If I am using a protein shake with just 20 grams in it is my body absurbing all of it? Do you think I would be waisting money on a shake with say 40grams?

[oddball182]

Originally posted by Deadgame
Ok the human body, so I have heard can only absorb between 20 to 25 grams of protein.

So if you eat a steak that has 100 grams of protein does this mean your only going to absorb around the 20 to 25 gram mark?

In other words do you have to take in a large amount of protein the get the target 20 to 25 gram mark?

If I am using a protein shake with just 20 grams in it is my body absurbing all of it? Do you think I would be waisting money on a shake with say 40grams?

to my knowladge there have been no studies that actually proove how much protein the body can digest in one sitting, but im am quite sure its more then 25g.

[xil]

Originally posted by Deadgame
Ok the human body, so I have heard can only absorb between 20 to 25 grams of protein.

So if you eat a steak that has 100 grams of protein does this mean your only going to absorb around the 20 to 25 gram mark?

In other words do you have to take in a large amount of protein the get the target 20 to 25 gram mark?

If I am using a protein shake with just 20 grams in it is my body absurbing all of it? Do you think I would be waisting money on a shake with say 40grams?

That's just an old wives tale that your body only absorbs 25grams of protein... so no, you will not be wasting your money with the shake and your body will continue to absorb the 40g of protein

[robertthoburn]

Originally posted by Deadgame
Ok the human body, so I have heard can only absorb between 20 to 25 grams of protein.

So if you eat a steak that has 100 grams of protein does this mean your only going to absorb around the 20 to 25 gram mark?

In other words do you have to take in a large amount of protein the get the target 20 to 25 gram mark?

If I am using a protein shake with just 20 grams in it is my body absurbing all of it? Do you think I would be waisting money on a shake with say 40grams?

Hi, Deadgame. That's an interesting question, one that is commonly asked and debated. What's interesting about the question is that the claim it stems from it isn't very clear.

I'm not at all criticizing you, Deadgame. Again, what I'm criticizing is the claim.

Think about it: "The body can only absorb 30 grams of protein in one setting." (I used 30 grams, because that's the most commonly cited figure I've heard.)

How do we define "one setting"?

There is no "one setting" in so far as the body is concerned. There is a gastrointestinal tract, which consist of your stomach, your small and large intestines.

When you eat protein, like any other macronutrient, it makes its way down your gastrointestinal tract. There, it is progressively 'torn apart' (digested), into smaller, more manageable pieces. 'Smaller, more manageable' meaning amino acids and small chains of amino acids ('peptides') that can be absorbed by the cells lining your intestine before passing into the blood stream.

How much of the protein you eat during "one setting" actually gets absorbed depends on a host of factors, including the way you actually measure "absorption", the duration of "one setting" (1 hour? 5 hours? until the gut is empty?), whether the protein is intact or hydrolyzed, and more.

Several years ago while working at MuscleTech I looked into this issue (I had nothing else to do). I remember finding a study dating back to the 1960s or 1970s or something like that where the researchers determined that it took a good 7-8 hours for a single patty of hamburger meat to be absorbed in humans. With this in mind, what's your definition of "one setting?"

Is a "setting" as long as it takes to digest all of the protein that you ate? Or do we draw a line in the sand at, say, 1 hour, and claim "enough is enough....this setting is over!" At that point, of course, only a fraction of the protein may have been absorbed. Thus, if a "setting" = 1 hour surrounding a meal, then the "only 30 grams protein can be absorbed in one setting" rule might not be all that far off when you consider the aforementioned study.

Another, possibly more relevant, study I found during my search was published by Zhao et al. (1997) in the Journal of Nutrition.

These researchers used dogs as their subjects. Of course, dogs aren't humans (though they may act like it at times). Correct me if I'm wrong, but they have shorter intestines than do humans. This makes extrapolating the findings to humans iffy, at best. Nevertheless...

Zhao et al. directly delivered, or 'perfused', either hydrolyzed or intact soy protein into the dogs' intestines over 120 minutes (2 hours). They found that the more hydrolyzed (less intact) was the protein, the more efficiently it was absorbed. They also found that the efficiency of absorption was not affected significantly by the load (amount) of protein delivered to the intestine. More on this in a second.

When the researchers perfused solutions containing 50-200 grams of soy protein/L into the dogs' intestines, 82.6-87.4% of the intact soy was absorbed. When they infused hydrolyzed soy protein solutions (100-400 g/L), 89.0-92.3% of the protein was absorbed. What this tells us is that under these particular conditions, the efficiency of protein absorption was pretty good whether the protein was intact (like most of the protein we eat) or hydrolyzed.

Now, just a second ago I said that Zhao et al. found that the efficiency of protein absorption was independent of the quantity of protein delivered to the intestine. If this is the case, you would expect the absolute amount of protein absorbed to increase as more protein is delivered to the intestine. And that's exactly what was found.

Zhao et al. reported that for hydrolyzed soy protein, 'maximal protein absorption' was reached at a protein load of 72 g (300 g/L). Increasing the load to 96 g (400 g/L) did not lead to significantly more protein getting absorbed (300 vs. 400 g/L: 47.0 ± 5.0 vs. 52.0 ± 5.9 g).

They also found that when the protein was delivered in an intact form, first half of the small intestine absorbed less of it as compared to the hydrolyzed protein. Thus, when intact protein was perfused into the intestine, more remained unabsorbed at more distal portions of the intestine than with hydrolyzed protein.

When Zhao et al. bumped up the protein load from 24 (100 g/L) to 48 g (200 g/L), the absolute amount of protein absorbed only rose very slightly --from 16 to 16.7 g when given intact. When hydrolyzed protein was given, however, it increaesd from 18.6 to 35.3 g.

Now, when you consider the time frame the perfusion was carried out over (120 minutes), all of a sudden the "30 gram" rule doesn't seem so crazy. But humans have different gastrointestinal tracts than do dogs (longer, I think), so we can't leap to any great conclusions just yet.

Also keep in mind that virtually all of the protein most human beings eat is "intact", i.e., not hydrolyzed. Just because less intact protein is absorbed in the first half of your small intestine, this does not mean that the second half won't absorb what arrives there. Zhao et al. reported that the intact protein actually slowed gastrointestinal transit. It kind of put the 'brakes' on the muscles linging the dogs' intestines, thereby enabling the protein to sit there a bit longer and get absorbed.

Remember, too, that the efficiency of protein absorption in Zhao et al.'s study remained pretty solid even when more protein was being delivered to the intestine. Still, it wasn't 100% efficient (no biological processes are), so the more protein 'fed' to the dogs, the more may have ended up being 'wasted'.

I apologize for not being able to come to a definitive conclusion. Unfortunately, there just isn't a plethora of research out their on this matter to allow it.

My intention in sharing the experiments above with you was to show you that when "one setting" is actually defined with a specific time frame, there will inevitably be limits to how much protein one human being can absorb in that "setting". As Zhao et al. and other studies suggest, the 30 gram rule may not be all that far off at all. Or, I could be wrong.

Hope this provides some useful, or at least, interesting insights.

Kindest regards,
Rob

REFERENCE CITED
Zhao X-T, McCamish MA, Miller RH, Wang L, Lin HC (1997). Intestinal transit and absorption of soy protein in dogs depend on load and degree of protein hydrolysis. J Nutr, 127: 2350-2356.

[Deadgame]

Wow great post Rob and thanks!

[str8flexed]

Originally posted by Deadgame
Ok the human body, so I have heard can only absorb between 20 to 25 grams of protein.

So if you eat a steak that has 100 grams of protein does this mean your only going to absorb around the 20 to 25 gram mark?

In other words do you have to take in a large amount of protein the get the target 20 to 25 gram mark?

If I am using a protein shake with just 20 grams in it is my body absurbing all of it? Do you think I would be waisting money on a shake with say 40grams?

you have heard wrong

[bkman4]

Your intestines are something like 23ft long. The reason you have a stomach is so you can be digesting your last meal and still pack yourself full of food. We evolved to make use of whatever we could get our hands on...if we didnt'...

[Chris_82]

great post rob, very helpfull.

[robertthoburn]

Originally posted by Chris_82
great post rob, very helpfull.

Thank you

[Meddller]

Is it possible to have too much protein powder in a day? What is a safe amount of protein to get from protein powder per day?

[str8flexed]

Is it possible to have too much protein powder in a day? What is a safe amount of protein to get from protein powder per day?

short answer... no. So long as you don't have any digestive problems with it... you could get all your protein from shakes if you wanted too.

[Evanarios]

Is it possible to have too much protein powder in a day? What is a safe amount of protein to get from protein powder per day?

I don't really know if there is "too" much protein. But eating

1g of Protein for Every Pound you weigh is pretty good...