Vegetarian Diet Reduces Kidney Stone Risk
Consuming a diet rich in meat and other animal-based proteins may increase the risk of developing uric acid kidney stones, according to a study in the European Journal of Nutrition (2003;42:332–7). Incorporating more vegetarian protein sources in the diet lowers uric acid levels in the blood and thereby prevents the formation of these types of kidney stones.
At some point in their lifetimes, more than 10% of all people in the United States will be affected by kidney stones (renal calculi). Studies suggest that 10 to 15% of all kidney stones are composed of uric acid, 75% of calcium oxalate, and the remainder of magnesium ammonium phosphate or cystine. Specific dietary factors influence the formation of each type of stone. Uric acid stones are primarily caused by consuming foods that contain large amounts of substances called purines (compounds formed during the breakdown of some protein-rich foods). Foods high in purines include meat, fish, seafood, legumes, and chocolate. Calcium oxalate stones may be formed by consuming foods high in oxalic acid, such as spinach, rhubarb, beet greens, nuts, chocolate, tea, bran, and strawberries. Ingesting animal protein sources, such as meat, dairy, poultry, and fish may also lead to calcium oxalate kidney stone formation, since these foods seem to increase the excretion of calcium in the urine.
Medications that block the formation of uric acid (such as allopurinol) may prevent uric acid kidney stones. A procedure called lithotripsy may also be used to help break the stones apart, making them easier to pass in the urine. However, the recurrence rate remains high, even with the procedure.
In the new study, ten healthy men between the ages of 21 and 32 consumed their regular diet for two weeks and then were asked to follow three different standardized diets for periods of five days each: (1) a typical Western diet, high in meat, dairy products, and alcohol; (2) a balanced protein diet with meat and vegetarian protein sources; and (3) a vegetarian diet that included dairy products and eggs. The latter two diets were low in purines and higher in water consumption. Daily urine samples were collected during each diet period and measured for uric acid content and pH. An increase in uric acid excretion in urine and more acidic pH are known risk factors for uric acid kidney stone development.
Urinary uric acid excretion during consumption of the balanced protein diet and the vegetarian diet was significantly lower, by 12 and 34% respectively, than that measured during the typical Western diet. Urinary pH also increased (became more alkaline) as more vegetarian protein sources were included as part of the diet. The risk of uric acid crystallization was significantly lower by 85% in the men while eating the balanced protein diet and 93% lower while consuming the vegetarian diet, compared with the risk during ingestion of the Western diet.
While the new study demonstrates that eating a vegetarian diet may reduce the risk of developing uric acid kidney stones, calcium oxalate stones are far more common and are not influenced by consumption of purine-rich foods. Dietary intake of large amounts of high-oxalate foods, such as spinach, beet greens, nuts, chocolate, tea, and strawberries may increase the risk of forming calcium oxalate stones. Studies suggest that taking supplemental potassium citrate (providing 1,600 mg per day of elemental potassium) with magnesium citrate (providing 500 mg per day of elemental magnesium) may prevent calcium oxalate kidney stones. However, taking large amounts of oral magnesium may cause loose stools in some individuals. Other studies suggest vitamin B6, vitamin E, and inositol hexaphosphate (IP-6) may also protect the kidneys against calcium oxalate stone formation. See your healthcare provider for specific dose information.
Darin Ingels, ND, MT (ASCP), received his bachelor’s degree from Purdue University and his Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. Dr. Ingels is the author of The Natural Pharmacist: Lowering Cholesterol (Prima, 1999) and Natural Treatments for High Cholesterol (Prima, 2000). He currently is in private practice at New England Family Health Associates located in Southport, CT, where he specializes in environmental medicine and allergies. Dr. Ingels is a regular contributor to Healthnotes and Healthnotes Newswire.
Copyright © 2004 Healthnotes, Inc. All rights reserved. Republication or redistribution of the Healthnotes® content is expressly prohibited without the prior written consent of Healthnotes, Inc. Healthnotes Newswire is for educational or informational purposes only, and is not intended to diagnose or provide treatment for any condition. If you have any concerns about your own health, you should always consult with a healthcare professional. Healthnotes, Inc. shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Healthnotes and the Healthnotes logo are registered trademarks of Healthnotes, Inc.