Protein is one of the most critical macronutrients, because it’s responsible for numerous functions in your body, including building and maintaining muscle, antibody production, muscle contraction and hormone synthesis. The popularity of high-protein diets, such as Atkins, has raised concerns over its effects on calcium depletion in the body. Evidence has shown mixed results regarding high-protein diets' impact on calcium loss.
Bone Mineral Density
Because calcium is stored in the bones, any type of bone loss results in calcium loss. Scientists at Purdue University assigned postmenopausal women to a higher- or lower-protein vegetarian diet for 12 weeks. Bone mineral density, an indicator of calcium status in bones, was measured before and after the study. At the end of the study, which was published in the October 2010 issue of "The Journals of Gerontology,” researchers found those in the higher-protein group experienced decreases in bone mineral density compared with those who followed a lower-protein diet.
Urinary Calcium Levels
Scientists at the University of Chicago studied the impact of a low-carb, high-protein diet on calcium metabolism in healthy men and women. Participants followed a low-carb diet for two weeks and then a moderate-carb diet for four weeks. Urinary calcium levels were measured before and after the study. Higher urinary calcium levels indicate a greater loss of calcium. Researchers discovered that participants experienced a significant increase in urinary calcium levels and a decrease in calcium balance. The findings were published in the August 2002 of "American Journal of Kidney Diseases.”
Bone Loss
Another study, published in the May 2006 issue of “Osteoporosis International,” found no effect of a low-carb, high-protein diet on bone loss. Researchers at the University of Florida found that overweight participants consuming a low-carb diet for three months experienced no changes in bone loss compared with those who followed a typical American diet.
No Effect
In research reported in the March 2004 issue of “The Journal of Nutrition,” scientists at Arizona State University assigned healthy adults to a high-protein or low-fat diet for six weeks. They found those following a high-protein diet didn’t experience increases in urinary calcium levels or a decrease in calcium balance compared with those following the low-fat diet.
References
- "The Journals of Gerontology"; Protein Intake, Weight Loss, and Bone Mineral Density in Postmenopausal Women; W.W. Campbell, et al.; October 2010
- "American Journal of Kidney Diseases"; Effect of Low-Carbohydrate High Protein Diets on Acid-Base Balance, Stone-Formation Propensity, and Calcium Metabolism; S.T. Reddy, et al.; August 2002
- EurekAlert; Low-Carbohydrate Diet Did Not Increase Bone Loss, Study Finds; May 2006
- "The Journal of Nutrition"; High-Protein, Low-Fat Diets Are Effective for Weight Loss and Favorably Alter Biomarkers in Healthy Adults; C.S. Johnson, et al.; March 2004
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