The Protein Myth:
 In
the past, some people believed one could never get too much protein.
In the early 1900s, Americans were told to eat well over 100 grams
of protein a day. And as recently as the 1950s, health-conscious
people were encouraged to boost their protein intake. Today, some
diet books encourage high-protein intake for weight loss, although
Americans tend to take in twice the amount of protein they need
already. And while individuals following such a diet have sometimes
had short-term success in losing weight, they are often unaware
of the health risks associated with a high-protein diet. Excess
protein has been linked with osteoporosis, kidney disease, calcium
stones in the urinary tract, and some cancers.
The building blocks of life
People build muscle and other body proteins from amino acids, which
come from the proteins they eat. A varied diet of beans, lentils,
grains, and vegetables contains all of the essential amino acids.
It was once thought that various plant foods had to be eaten together
to get their full protein value, but current research suggests this
is not the case. Many nutrition authorities, including the American
Dietetic Association, believe protein needs can easily be met by
consuming a variety of plant protein sources over an entire day.
To get the best benefit from the protein you consume, it is important
to eat enough calories to meet your energy needs.
The trouble with too much protein
The average American diet contains meat and dairy products. As
a result, it is often 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. Such a
diet reduces the excess levels of nitrogen and can also help prevent
kidney disease.
- Cancer: Although fat is the dietary substance most often singled
out for increasing cancer risk, protein also plays a role. Populations
who eat meat regularly are at increased risk for colon cancer,
and researchers believe that the fat, protein, natural carcinogens,
and absence of fiber in meat all play roles. The 1997 report of
the World Cancer Research Fund and American Institute for Cancer
Research, Food, Nutrition, and the Prevention of Cancer, noted
that meaty, high-protein diets were linked with some types of
cancer.
- Osteoporosis and Kidney Stones: Diets that are rich in animal
protein cause people to excrete more calcium than normal through
their kidneys and increase the risk of osteoporosis. Countries
with lower-protein diets have lower rates of osteoporosis and
hip fractures.
Increased calcium excretion increases risk for kidney stones. Researchers
in England found that when people added about 5 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.
For a long time it was thought that athletes needed much more protein
than other people. The truth is that athletes, even those who strength-train,
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.
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