So What's The Deal With The 30 Gram Protein Rule

Custom Search

Question : 30 Gram Protein Rule

Hey Will, I was told by a trainer in my gym that 30 grams of protein is the
upper limit a person can digest, but he could not tell me where that rule
comes from. He said it was a "known fact" and walked away when I
questioned his source. So what is the deal with this 30 gram rule? Is this guy
full of it or should I worry about it? My stats are: 5'9" and 220lbs with about
10% bodyfat. I lift weights (heavy!) 4 days per week and do aerobics 2-3 day
per week. Thank you, Daniel Lopez

It has been a long debated topic how much protein a person can digest at any
one time. Nutritionists and doctors have maintained for decades that "people
can only digest 30 grams at a time of protein and any additional protein is
wasted or converted to fat." So say the powers that be.

Now, I wish I could examine the study or research they are basing this advice
on so I could dispute it but I can't. Why you ask? Because in all my years of
searching the medical data banks, talking to researchers, and falling asleep
in the medical library after hours of reading, I have been unable to find exactly
where this advice comes from or what it's based on.

At one time, I went so far as to offer a reward to anyone who could show me a
recent study that showed that 30 grams of protein was the upper limit anyone
could digest, regardless of age, weight, and activity levels.

Why is it 30 grams? Why not 28 or 35? Are we saying that the digestive and
absorptive abilities of a 285 pound 23 year old football player is the same as
a 50 year old 115 pound women?

Now digestion is a very complex topic. Many people think you eat some
protein, it mixes with some acid or something, gets broken down into amino
acids, gets taken up into the body, and everyone is happy.

I wish it were that simple. As with all foods, the breakdown of protein starts in
the mouth with the simple chewing of food and the exposer to certain
enzymes. In the stomach, food mixes with enzymes and other factors such as
lipase, pepsin, intrinsic factor, and of course HCL (stomach acid).

It moves onto the small intestine and then the large intestine.The small nutrient
absorption and is made up of section such as the duodenum, jejunum, and
the ileum. Pancreatic enzymes (chymotrypsin, trypsin, etc.), bile salts, gastrin,
cholecystokinin, pepidases, as well as many others factors are released here.

The large intestine is composed of the ascending colon, transverse colon,
descending colon, and the sigmoid colon, which all play a part in absorbing
the nutrients we eat. Sound complicated? It is. Believe me, I am leaving out a
great deal of information so you wont fall asleep reading my little column!
Suffice it to say, digestion is a very complicated thing and there are many
places along the chain of digestion that can both enhance and degrade a
persons ability to absorb the foods we eat.

There is no reason to think that among this complicated process that there
are not wide individual differences in a persons ability to digest and absorb
protein. For some person who is inactive, elderly, and for what ever reason
lives with compromised digestion, 30 grams of protein at one sitting might
very well be too much for them to handle.

By the same token, assuming a 220lbs healthy athlete is unable to exceed 30
grams of protein in one sitting is neither proven by medial science or even
logical in my view. So what if the 30 gram rule turns out to be true? If we
examine some of the more recent studies on the protein requirements of
athletes done by researchers from both the United Sates and Canada , we
come to some recommended protein intakes that far exceed the RDAs,
some times by as mush as 225%!

These researchers came to the conclusion that protein intakes for athletes
should range from approximately 1.2 grams of protein per kilogram of
bodyweight for endurance athletes and up to 1.8g of protein per kg for
strength training athletes. For a 200 pound bodybuilder-a strength training
athlete-that would be approximately 164 grams of protein per day (most
bodybuilders I know eat considerably more protein per day, but that's for
another fight and another article...). Assuming that 30 grams of protein is the
most anyone can digest, absorb, and utilize, this person would have to split
his intake into about five meals (164 divided by 30 = 5.47). So, given the
advice by many people that 30 grams is all anyone can digest at a single
sitting, it appears a person can achieve the goal of 30 grams of protein per
meal even with the higher intakes recommended in the modern research
(assuming they are willing or able to eat five meals per day).

However, if you happen to eat more than that per meal as a healthy athlete I
don't think you have anything to worry about. I wont tell anyone. Me, I would
suggest you stick to the one gram per pound of bodyweight rule, which often
exceeds the research mentioned above. Also, read the "Protein Myth" article
at the BrinkZone site for more info on this topic.