Date: Thu, 1 Oct 92 10:53:24 EDT
From: wheeler@super.org (Ferrell S. Wheeler)
To: tms@cs.umd.edu
Subject: PCRM Protein



THE PROTEIN MYTH

     In the past, some people believed one could never get too much protein.
In the early 1900's, Americans were told to eat well over 100 grams of
protein a day. And as recently as the 1950's, health-conscious people were
encouraged to boost their protein intake. The reality is that the average
American takes in twice the amount of protein he or she needs. Excess
protein has been linked with osteoporosis, kidney disease, calcium stones
in the urinary tract, and some cancers. Despite all this, many people still
worry about getting enough protein. 

* The Building Blocks of Life
     People build the proteins of their bodies from amino acids, which, in
turn, come from the proteins they eat. Protein is abundant in nearly all
of the foods people eat. A varied diet of beans, peas, lentils, grains, and
vegetables contains all of the essential amino acids. Animal products are
high in protein, but are undesirable because of their high fat and
cholesterol content. Fat and cholesterol promote heart disease, cancer, and
many other health problems. One can easily meet the body's protein
requirements with plant foods. It used to be believed that various plant
foods had to be eaten together to get their full protein value, but many
nutrition authorities, including the American Dietetic Association, have
determined that intentional combining is not necessary.1 As long as one's
diet includes a variety of grains, legumes, and vegetables, protein needs
are easily met. 

* The Trouble With Too Much Protein
     The average American diet contains meat and dairy products. As a result,
it is too high in protein. This can lead to a number of serious health
problems:

Kidney Disease
     When people eat too much protein, they take in more nitrogen than they
need. This places a strain on the kidneys which must expel the extra
nitrogen through urine. People with kidney disease are encouraged to eat
low-protein diets.2 Such a diet reduces the excess levels of nitrogen and
thus can help prevent kidney disease too.

Cancer
     Although fat is the dietary substance most often singled out for
increasing one's risk for cancer, protein also plays a role. Populations
that eat meat regularly are at an increased risk for colon cancer,3 and
researchers believe that the fat, protein, natural carcinogens, and the
absence of fiber in meat all play roles. In 1982, the National Research
Council noted a link between cancer and protein.4

Osteoporosis and Kidney Stones
     Diets that are rich in protein, especially animal protein,5 are known to
cause people to excrete more calcium than normal through their urine6 and
increase the risk of osteoporosis. Countries with lower-protein diets have
lower rates of osteoporosis and hip fractures.7 This holds true even in
countries with low calcium intake.
     Increased calcium excretion increases risk for kidney stones. Researchers
in England found that by adding about five ounces of fish (about 34 grams
of protein) to a normal diet the risk of forming urinary tract stones
increased by as much as 250 percent.8
     For a long time it was thought that athletes needed much more protein
than other people. The truth is that athletes need only slightly more
protein, which is easily obtained in the larger servings athletes require
for their higher caloric intake. Vegetarian diets are great for athletes.
     To consume a diet that contains enough, but not too much, protein, simply
replace animal products with grains, vegetables, legumes (peas, beans, and
lentils), and fruits. As long as one is eating a variety of plant foods in
sufficient quantity to maintain one's weight, the body gets plenty of
protein.

References:

1. Position of the American Dietetic Association: Vegetarian diets. J Am
Diet Assoc, 1988;88:351-355.
2. El Nahas AM, Coles GA. Dietary treatment of chronic renal failure: ten
unanswered questions. The Lancet, 15 March 1986:597-600.
3. Pellet PL. Protein requirements in humans. Am J Clin Nutr, 1990;51:723-
37.
4. Committee on Diet, Nutrition, and Cancer of the National Research
Council. Diet, Nutrition, and Cancer. Washington, DC, 1982.
5. Zemel MB. Calcium utilization: effect of varying level and source of
dietary protein. Am J Clin Nutr, 1988;48:880-3.
6. Sherman HC. Calcium requirement in man. J Biol Chem, 1920;44:21.
7. Hegsted DM. Calcium and osteoporosis. J Nutr, 1986;116:2316-2319.
8. Robertson PJ, et al. The effect of high animal protein intake on the
risk of calcium stone-formation in the urinary tract. Clinical Science,
1979;57:285-288.

Physicians Committee for Responsible Medicine
P.O. Box 6322
Washington, DC 20015
(202) 686-2210
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