Exercise, bone and nutrition

Predisposition to poor skeletal health resulting in osteoporotic fracture i s a major public health problem, the future economical impact of which is l ikely to be phenomenal. Two mechanisms principally determine adult bone hea lth: (1) maximum attainment of peak bone mass (PBM); (2) the rate of bone l oss with advancing age. Both aspects are regulated by a combination of endo genous and exogenous factors, and although genetic influences are believed to account for up to 75 % of the variation in bone mass, there is still roo m for modifiable factors to play a vital role. Weight-bearing physical acti vity is beneficial to the skeleton, but clarification of the exact type, in tensity and duration required for optimum bone mass is needed. Excessive le vels of exercise, which result in amenorrhoea, are detrimental to skeletal health. The importance of Ca to bone remains controversial. There is eviden ce that Ca is effective in reducing late post-menopausal bone loss, but mor e research is required on the long-term benefit of increased Ca intake on P BM attainment. Vitamin D 'insufficiency' appears to be widespread amongst p opulation groups and is an area of considerable public health concern. The role of other micronutrients on bone metabolism remains to be fully quantif ied, but data from a combination of experimental, clinical and observationa l studies suggest a positive link between alkaline-forming foods and indice s of bone health. The influence of nutrient-gene interactions on the skelet on requires further elucidation, but it may be useful in the future to targ et nutrition advice at those individuals who are genetically susceptible to osteoporosis.