NIH

The Mount Zion Osteoporosis Center at the University of California at San Francisco have been funded to study the effect of dietary protein source on various aspects of calcium metabolism in post-menopausal women. Baylor College of Medicine is involved as a sub-contract to assist in the measurement of calcium absorption bythese subjects using validated stable isotope methods.

Osteoporosis is a major health concern worldwide, particularly among postmenopausal women, as health care improves and the population ages. Estimates of the financial impact of the disease range into the billions of dollars. While there are drugs available for the treatment and prevention of osteoporosis, they are too expensive for population-wide prevention efforts, and there are no long-term data on their efficacy and safety. Research into the impact of safe, widely available interventions, such as dietary recommendations, on bone health could have important, clinically significant public health ramifications. Dietary protein has the potential to have such an impact. The relationship between dietary protein intake and skeletal health during aging is complex, in part because different sources of dietary protein may have different effects on bone metabolism. Animal protein may increase fracture risk by providing a dietary acid load, leading to negative calcium balance and increased bone resorption. In contrast, vegetable sources of protein, while providing some acid due to their protein content, provide proportionally more base that counters the dietary acid load. The effect of dairy products, which are rich in animal protein but also contain potential base precursors not found in vegetable foods, has not been established. Finally, soy protein sources may have a dual benefit: soy foods provide base precursors as well as plant estrogens that may have a beneficial effect on bone.

In this randomized clinical trial of 176 postmenopausal women, we will explore the impact of four dietary protein sources upon calcium absorption as assessed by stable isotope studies.

Other

The calcium absorption study has slight risk of pain or discomfort from the (iv) infusion, and minial risk of infection. These will be minimized by having trained persons doing the infusions. There are no know risks to the stable isotopes. There are no risk to the urine collection.

There are no direct benefits to subjects