From: abulsari@abo.fi (Abhay Bulsari VT)
Subject: The protein myth
Organization: Abo Akademi University
Date: Sat, 26 Sep 1992 11:40:28 GMT


From: Michael Traub <traub@btcs.bt.co.uk>


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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