Wednesday, July 22, 2009
One of the more pervasive ideas about bodybuilding diets is the notion that high protein intakes are a health risk. Dire warnings about higher than recommended protein intakes causing increased rates of bone loss and “stress” to the kidneys, have been shown to be false by extensive and ac- curate studies. Nonetheless, this misunderstanding persists.
In fact, recent research has shown potential health uses for higher protein
intakes. Other studies continue to suggest that higher protein intakes dur-
ing a diet may be superior to other diets for fat loss, though the use of
high protein diets for weight loss is still debated in nutritional and medical
One review study that examined the above issues, “Optimal Intakes of Pro-
tein in the Human Diet,” came to some interesting conclusions on the issue
of protein and its potential health uses and safety issues.
The study outlined an extensive body of recent data showing that high
protein diets may, in fact, be bene cial for reducing blood pressure and
stroke mortality. Though some early studies appeared to show that higher
protein intakes caused an excretion of calcium, which would ultimately
lead to bone loss, recent studies have debunked that assertion. On the
matter of bone loss, the review paper concludes:
“For bone health, the established views of risk of high protein intakes are not
supported by newly-emerging data, with bene ts indicated in the elderly.”
Interestingly, a large body of research is now showing that the elderly may
in fact require higher intakes of protein than is currently being recom-
Regarding the potential for protein to stress the kidneys, though research
suggests that people with pre-existing kidney disease should avoid high
protein diets, no data has ever shown kidney function to be compromised
in healthy adults and the above review study con rms this nding. A re-
cent study that examined the renal (kidney) function of athletes who follow
a high protein diet– that is, protein intake well above the US RDA – found
no negative e ects on the kidney function of these athletes.
So what’s the take-home from the above? It is arguable whether or not ath-
letes require additional protein to maintain their lean muscle mass and/or
increase it, though most modern research appears to con rm they indeed
should eat additional protein.
The point is, regardless of whether or not athletes need additional protein,
higher protein intakes do not appear to pose any health hazards to healthy
active people. And higher protein intakes may in fact have health uses of
their own as has been found in a plethora of emerging research.
Another myth concerns how much protein a person can digest at any one
time. Nutritionists and doctors maintained for decades that, “people can
only digest 30 grams at a time of protein and any additional protein is
Now, I wish I could examine the study or research they are basing this ad-
vice on so I could dispute it, but I can’t.
Why, do you ask? Because in all my years of searching the medical data
banks, talking to researchers and falling asleep in the medical library af-
ter hours of reading, I have been unable to nd exactly where this advice
comes from or what it’s based on.
At one time, I went so far as to o er 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 ability of a 285 pound, 23 year old football player is the same as
a 50 year old, 115 pound woman?
But to be completely fair, let’s assume for the moment that the 30 grams
rule turns out to be true. As discussed earlier, some of the studies done
by researchers over the last decade on the protein requirements of ath-
letes recommend intakes that exceed the RDAs by as much as 225 percent!
These range from approximately 1.2 grams of protein per kilogram of body
weight for endurance athletes, and up to 1.8g of protein per kg for strength
For a 200 pound bodybuilder – a strength training athlete – that would be
approximately 164 grams of protein per day. Assuming that 30 grams of
protein is the most anyone can digest, absorb and utilize at a time, this
person would need to split his intake into about 5 - 6 meals (164 divided by
30 = 5.47) - which is what most bodybuilders do anyway.
In other words, even if the “rule” was true, there would be no cause for con-
cern that much protein would be wasted, since the intake per meal would
still be under (or close to) the theoretical “limit.”
Nonetheless, the assumption that a 200+ lb. healthy athlete is unable to
exceed 30 grams of protein in one sitting is neither proven by medical sci-
ence nor even logical in my view.
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 ami-
no 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 exposure to certain
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 intestine is con-
sidered the major anatomical site of food digestion and nutrient absorp-
tion and is made up of sections such as the duodenum, jejunum, and the
Pancreatic enzymes (chymotrypsin, trypsin, etc.), bile salts, gastrin, chole-
cystokinin, peptidases, 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 absorb-
ing the nutrients we eat.
Sound complicated? It is. Believe me, I am leaving out a great deal of infor-
mation so you won’t fall asleep!
Su ce 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
person’s ability to absorb the foods we eat. This is a complex process, so
there are likely to be wide individual di erences in the ability to digest and
absorb protein. For the person who is inactive or lives with compromised
digestion (for whatever reason), 30 grams of protein at one sitting might
very well be too much to handle.
Even that’s speculation, however. A 1999 study, “Protein pulse feeding
improves protein retention in elderly women” fed 15 elderly women 80%
of their total daily protein intake in a single meal (lunch). The result was
improved nitrogen retention vs. the same total protein intake spread out
over 4 meals. The researchers fed the women 1.7 g protein/kg of fat-free
mass. If we assume the women in the study were small and frail, with a lean
mass of only 40 kg (88 lb.), their intake works out to 68 g protein per day.
In the experiment, they consumed 80% of that total in a single meal. That
would be a bit over 54 g protein at one sitting. Now maybe 100% wasn’t
digested/absorbed, but most of it must have been - as their nitrogen status
was better than when they consumed the protein in smaller increments
throughout the day.
So if elderly women were able to digest and utilize more than 30 grams of
protein in a single meal, why wouldn’t a healthy, active man or woman be
So if you happen to eat more than 30 g of protein per meal, I don’t think
you have anything to worry about. I won’t tell anyone.