Calcium and vitamin D.

Calcium is required for normal growth and development as well as maintenance of the skeleton. Vitamin D is also essential for intestinal calcium absorption and plays a central role in maintaining calcium homeostasis and skeletal integrity. In addition, both micronutrients have important roles in non-skeletal-related physiological processes. Of concern, significant proportions of some population groups fail to achieve the recommended calcium intakes in a number of western countries. Furthermore, while cutaneous biosynthesis upon exposure of skin to ultraviolet B light is the major source of vitamin D for most people, this does not occur during winter time. Thus, there is an increased reliance on dietary sources during winter months to help maintain adequate vitamin D status. Since vitamin D is found naturally only in a limited number of foods, the usual dietary vitamin D intake by many European populations is not sufficient to maintain adequate vitamin D status. This paper will briefly review these important issues together with consideration of the potential role for supplementation with calcium and vitamin D in terms of improving their intakes in the population. It will also focus on the issues of efficacy as well as safety considerations of supplements.