Animal Aid


As part of our Veggie Month campaign, we take a look at the question of protein and the vegetarian diet.

Most people in the West eat far more protein than they need, and there are now diet fads - endorsed by high profile celebrities - that encourage the consumption of potentially dangerous protein levels as an aid to weight loss.

Excess protein has been linked with osteoporosis, kidney disease, calcium stones in the urinary tract, and some cancers.

The building blocks of life

Proteins are the building blocks that make up and regulate the cells of our bodies. They are composed from amino acids, which, in turn, come from the proteins that we eat. Many plant foods are a rich protein source - for example: peas, beans, lentils, beansprouts and whole grain rice and cereals.

The trouble with too much protein

The average diet - rich in meat and dairy products - contains too much protein. This can lead to a number of serious health problems:

Kidney disease

A consequence of excess protein consumption is that more nitrogen than the body requires is taken in. This strains the kidneys, which must expel the extra nitrogen through urine. People with kidney disease are encouraged to eat low-protein diets (1). As well as reducing the nitrogen levels, a low-protein diet can also prevent kidney disease.


Too much fat in the diet is the food-related factor most often identified for increasing one's risk of contracting cancer. But protein also plays a role. Populations that eat meat regularly are at an increased risk for colon cancer (2). In 1982, the American National Research Council noted a link between cancer and protein (3).

Osteoporosis and kidney stones

Diets rich in protein, especially animal protein (4), cause the excretion of more calcium than is normal through the urine (5). This increased calcium excretion increases risk of kidney stones, while the calcium loss increases the risk of osteoporosis. Countries whose populations eat low-protein diets have lower rates of osteoporosis and hip fractures (6).

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. Eat enough - and of sufficient variety - to maintain your body weight and there will be no risk of protein deficiency.


  1. El Nahas AM, Coles GA. Dietary treatment of chronic renal failure: ten unanswered questions. Lancet 15 March 1986:597-600.
  2. Pellet PL. Protein requirements in humans. Am J Clin Nutr 1990;51:723-37.
  3. Committee on Diet, Nutrition, and Cancer of the National Research Council. Diet, Nutrition, and Cancer. Washington, DC, 1982.
  4. Zemel MB. Calcium utilization: effect of varying level and source of dietary protein. Am J Clin Nutr 1988;48:880-3.
  5. Sherman HC. Calcium requirement in man. J Biol Chem 1920;44:21.
  6. Hegsted DM. Calcium and osteoporosis. J Nutr 1986;116:2316-9.

The above information is drawn from an article produced by the Physicians Committee for Responsible Medicines. See their excellent website - - for further background.

Go veggie - it's easier than you think.

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