The Effect of Protein Supplementation on Bone Health in Healthy Older Men and Women

Dietary protein plays an important role in maintaining balanced calcium levels in the body. Protein's impact on skeletal health remains unclear. It is well accepted that increasing dietary protein results in greater excretion of calcium through urine. The excreted calcium is thought to come in part from bone, which would suggest a negative effect on bone health. However, recent studies have found that higher protein intake is, in fact, associated with higher bone mineral density and lower rates of bone loss. The purpose of this study is to determine if a daily protein supplement will improve bone health and hormonal measures of bone metabolism among healthy older men and women who consume low-to-normal levels of dietary protein. This study will last 18 months. For the duration of the study, participants will be randomly assigned to receive either a 40-gram protein supplement or placebo daily. There will be a total of nine study visits that will occur at screening, study entry, Month 1.5, and every three months thereafter. Dietary records, nutritional counseling, glucose finger stick tests, and questionnaires related to falls, physical activity, habits, and study satisfaction will occur at all study visits. Blood and urine collection, functional testing, and bone mineral density (BMD) testing will occur at selected visits. At Months 0 and 18, half of the participants will undergo a quantitative computed tomography (CT) scan to determine bone mineral density.