Nutritional factors in bone health in elderly subjects: methodological and contextual problems.

Five problem areas relating to the assessment of nutritional influences on bone health in elderly subjects are described. These are 1) complexity of the domain of bone health, 2) difficulty in detecting bone fragility in vivo, 3) difficulty in detecting useful changes in bone mass, 4) remodeling transients, and 5) lack of standards for assessing adequacy of vitamin D nutriture in elderly subjects. The first four are inherent to the tissue being studied and the last is definitional. Strategies are available for dealing with some of these problems; others seem inherently intractable. However, understanding the basis for all of them can at least help avoid both entering upon futile research and misinterpretation of experimental results.