Is the recommended daily allowance for vitamin D too low for the homebound elderly?

A population of sunlight-deprived elderly was studied to determine the daily intake of vitamin D and whether dietary intake was sufficient to maintain a normal vitamin D status. Twenty-two subjects over 65 years old with serum creatinine less than 180 mumols/L and confined indoors for more than 6 months were chosen from the community and a nursing home in Southeast Baltimore. Three-day food records were obtained along with serum levels of 25-hydroxyvitamin D (25-OHD), 1,25-dihydroxyvitamin D (1,25-(OH)2 D), and intact parathyroid hormone (PTH). The mean daily vitamin D intake was over twofold greater than the adult Recommended Daily Allowance (RDA) of 200 IU. The mean 25-OHD level was 40 nmol/L (normal 25-138 nmol/L) with seven patients less than 25 nmol/L. Of these participants with 25-OHD values less than 25 nmol/L, the mean vitamin D intake was 467 IU (range 36-1096 IU). We conclude that the current RDA seems inadequate for many older individuals who do not get sun exposure. This particular population of elderly is at risk to develop vitamin D deficiency and the associated complications.