Dietary protein and bone health

The public is often advised to limit their consumption of animal proteins because of the concern about increased calcium loss associated with high protein intake. Unfortunately, this advice is primarily based on studies that found hypercalciuric effects of purified proteins. Attempts to test common sources of protein have suffered from significant design and methodological limitations; epidemiologic studies of the effects of protein on bone health have yielded mixed results. Findings from three recent, carefully controlled feeding studies, summarised below, show that a moderately high intake of animal protein does not adversely affect calcium retention and may even be beneficial for bone health. Several milk/dairy supplementation trials also indicate that a concomitant increase in calcium and protein intake (along with other nutrients present in these foods), favourably affects bone health at various stages of the life cycle. Nonetheless, the effects of animal protein on bone health remain unclear. Carefully controlled feeding studies are needed to better understand the effects of dairy proteins per se, as well as milk and milk products as whole foods, on calcium homeostasis and bone health.