Vegan Health ArticlesNutrition and Renal Disease
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Problem Foods 

Animal Protein. Animal proteins cause calcium to be leached from the bones and excreted in the urine where it can form stones. Diets rich in animal proteins also increase uric acid excretion. In a controlled research study, published in the American Journal of Clinical Nutrition, research subjects on a diet eliminating animal protein had less than half the calcium loss that they had on their baseline diet.12

The Harvard study mentioned earlier found that even a modest increase in animal protein, from less than 50 grams to 77 grams per day, was associated with a 33 percent increased risk of stones in men.7 The same is true for women. The Nurses’ Health Study, a long-term study of health factors in a large group of women, revealed an even greater risk of stones from animal protein than was found in previous studies in men.9

The association between animal proteins and stones probably relates both to the amount of protein they contain and to their content of the sulfur-containing amino acids. In particular, the sulfur in cystine and methionine is converted to sulfate, which tends to acidify the blood. As a part of the process of neutralizing this acid, bone is dissolved, and bone calcium ends up in the urine. Meats and eggs contain two to five times more of these sulfur-containing amino acids than are found in grains and beans.11,13

Between 1958 and the late 1960s, there was a sharp increase in the incidence of kidney stones in Great Britain. During that period, there was no substantial change in the amount of calcium or oxalate-containing foods consumed. However, the consumption of vegetables decreased, and the use of poultry, fish, and red meat increased. Statistical analyses showed a strong relationship between the incidence of stones and animal protein consumption.14

Sodium. Sodium increases the passage of calcium through the kidney and increases the risk of stones.9 When people cut their salt (sodium chloride) intake in half, they reduce their daily need for calcium by about 160 milligrams.15

Plants of any kind—grains, vegetables, legumes, and fruits—contain almost no sodium at all unless it is added during canning or other processing. Dairy products and meats contain more salt than plant products, and table salt, frozen meals, and canned and snack foods are the highest-sodium food products. For more information, see the sodium/potassium chart in Section 5..

Sugar. Sugar accelerates calcium losses through the kidney.16 In the Nurses’ Health Study, those who consumed, on average, 60 grams or more of sugar (sucrose) per day had a 50 percent higher risk of stones than those who consumed only about 20 grams.9

Candy bar (2 ounces) 22-35
Cookies (3) 11-14
Corn flakes (1 cup, 28 grams)
2 Frosted corn flakes (1 cup, 41 grams)
17 Crackers (5) 1
Fruit cocktail (1/2 cup, 124 grams) 14
Grape jam (1 tablespoon) 13
Ice cream (1/2 cup, 106 grams) 21
Soda (12 ounces)
40 White bread (2 slices) 1
Source: package information

Climate. Kidney stones are also more common in warm climates, presumably because perspiration leads to dehydration and a more concentrated urine, and because sunlight increases the production of vitamin D in the skin which, in turn, increases calcium absorption from the digestive tract.17

Surprisingly, oxalate-rich foods, such as chocolate, nuts, tea, and spinach, are not associated with a higher risk of renal stones,7 nor is vitamin C, even though it can be converted to oxalate. A large study of men taking vitamin C supplements found that they had no more kidney stones than men who do not take them.8

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We began this archive as a means of assisting our visitors in answering many of their health and diet questions, and in encouraging them to take a pro-active part in their own health. We believe the articles and information contained herein are true, but are not presenting them as advice. We, personally, have found that a whole food vegan diet has helped our own health, and simply wish to share with others the things we have found. Each of us must make our own decisions, for it's our own body. If you have a health problem, see your own physician.