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Epidemiology of bone mass in premenopausal women.

The belief that optimal bone mass counters considerable bone loss during the perimenopausal period has led to much research to depict premenopausal bone mass and to identify factors which optimize it. Research consistently shows that genetics play a strong role in peak bone mineral density. In fact familiality explains 10% to more than 50% of premenopausal bone mass. Studies of bone density levels in ovariectomized and amenorrheic women indicate that estrogen is needed to maintain premenopausal bone mass. The link between reproduction and estrogens role is not yet clear however. Strenuous exercise in amenorrheic women is related to bone loss. On the other hand moderate physical exercise in women with normal menstruation patterns optimizes premenopausal bone density within each womans genetic potential. A possible intervention to reduce bone loss is through the diet especially calcium intake. Yet the levels of nutrients and the timing of dietary intervention are not clear. Current recommended levels of nutrients have not been disproved however. Longitudinal studies are needed to determine what happens to premenopausal bone mass levels during the perimenopausal period. These studies would be especially useful if they could identify characteristics of women who lose bone rapidly and of those who lose it slowly. Future research needs to identify the time for and length of maximum mineralization of bone. Knowing this would help prevention programs increase their effectiveness. Future research also needs to determine what factors are related to differences in premenopausal bone density. Research activities that determine the contribution of nutrition exercise and reproductive events (pregnancy nulliparity parity lactation) must continue. They should also examine possible interactions between these factors. They must consider sample size and selection of controls.