Effect of vitamin D supplementation in the institutionalized elderly.

An intervention study with vitamin D supplementation was conducted in order to study the amount of vitamin D required in the elderly. Sixty-four institutionalized elderly were randomly assigned to two groups: group (A) to take a beverage containing 200 mg calcium daily, and group (B) to take a beverage containing 200 mg calcium and 5 microg vitamin D daily for 30 days. Prior to the study, the subjects' average vitamin D intake was 7.3 microg/day, which is approximately 150% of the current adequate intake (AI), however their mean plasma 25 OH-D level at baseline was only 12 ng/mL, strongly indicating hypovitaminosis D. During the study, average plasma 25 OH-D concentration significantly increased to 14.7 ng/mL in group (B), but not in group (A). However, group (B) was still in the hypovitaminosis range. Thus, daily intake exceeding the current AI of 5 microg is required for the institutionalized elderly.