For years, research questioned the role of dietary protein in bone health. Metabolic balance studies in the 1970s and early 1980s showed higher protein intakes increased urinary calcium but did not enhance intestinal calcium absorption, leading to the conclusion that the source of the additional urinary calcium must be from bone breakdown (1-8). However, recent short-term dietary intervention studies using more sophisticated methodologies have refuted this conclusion, demonstrating that protein increases intestinal calcium absorption more than urinary calcium excretion, therefore not leading to bone breakdown as originally hypothesized (9-11).

The source of protein has also been considered, with some scientists suggesting that animal-based protein was detrimental to bone relative to plant-based protein. However, a recent analysis published in PLoS One demonstrates otherwise (12). The systematic review and meta-analysis evaluated the effects of animal versus plant protein intake on bone mineral density (BMD), bone mineral content and select bone biomarkers in healthy adults. The meta-analysis results showed no differences between plant and animal proteins when it comes to BMD outcomes.

For more information and other research on protein and bone health, read, “Eat Protein for Bone Health?”.

1. Hegsted M, Linkswiler HM. Long-term effects of level of protein intake on calcium metabolism in young adult women. J Nutr. 1981;111(2):244-51.
2. Schuette SA, Hegsted M, Zemel MB, Linkswiler HM. Renal acid, urinary cyclic AMP, and hydroxyproline excretion as affected by level of protein, sulfur amino acid, and phosphorus intake. J Nutr. 1981;111(12):2106-16.
3. Schuette SA, Zemel MB, Linkswiler HM. Studies on the mechanism of protein-induced hypercalciuria in older men and women. J Nutr. 1980;110(2):305-15.
4. Anand CR, Linkswiler HM. Effect of protein intake on calcium balance of young men given 500 mg calcium daily. J Nutr. 1974;104(6):695-700.
5. Hegsted M, Schuette SA, Zemel MB, Linkswiler HM. Urinary calcium and calcium balance in young men as affected by level of protein and phosphorus intake. J Nutr. 1981;111(3):553-62.
6. Kim Y, Linkswiler HM. Effect of level of protein intake on calcium metabolism and on parathyroid and renal function in the adult human male. J Nutr. 1979;109(8):1399-404.
7. Spencer H, Kramer L, DeBartolo M, Norris C, Osis D. Further studies of the effect of a high protein diet as meat on calcium metabolism. Am J Clin Nutr. 1983;37(6):924-9.
8. Allen LH, Oddoye EA, Margen S. Protein-induced hypercalciuria: a longer term study. Am J Clin Nutr. 1979;32(4):741-9.
9. Kerstetter JE, O’Brien KO, Caseria DM, Wall DE, Insogna KL. The impact of dietary protein on calcium absorption and kinetic measures of bone turnover in women. J Clin Endocrinol Metab. 2005;90(1):26-31.
10. Hunt JR, Johnson LK, Fariba Roughead ZK. Dietary protein and calcium interact to influence calcium retention: a controlled feeding study. Am J Clin Nutr. 2009;89(5):1357-65.
11. Roughead ZK. Controlled high meat diets do not affect calcium retention or indices of bone status in healthy postmenopausal women. J Nutr. 2003:1020-6.
12. Shams-White MM, et al. Animal versus plant protein and adult bone health: A systematic review and meta-analysis from the National Osteoporosis Foundation. PLoS One. 2018 Feb23;13(2):e0192459.