16 August 2002
Elderly people who take vitamin A supplements are at risk of osteoporosis, US research shows.
Vitamin A consumption only slightly above the recommended daily intake (RDI), but well within the upper limits for safety, was enough to start reducing bone mineral density (BMD), the researchers said.
This suggests there is a 'delicate balance' between vitamin A deficiency and toxicity in elderly people (Journal of Bone and Mineral Research 2002; 17: 1349-58).
Four-year follow-up of 958 elderly people living in the community showed BMD was highest when they had a vitamin A intake of 2000-2800 IU.
But BMD decreased as the intake rose beyond this level.
The people most likely to have a vitamin A intake greater than the RDI were those taking vitamin A supplements (whether alone or as multivitamins).
'The chronic excessive ingestion of vitamin A and other retinoids is a significant risk factor for reduced bone mass, osteoporosis, and subsequent fragility fractures,' an editorialist said.
The editorialist recommended that elderly people should obtain all their vitamin A from foods with natural vitamin A or fortified with vitamin A, and that they should take supplements only if they were truly vitamin A deficient.
|Vitamin A facts|
The recommended daily intake for vitamin A is approximately 2500 IU, Food Standards Australia New Zealand says.
According to MIMS June/July 2002, vitamin A doses range between 580 and 5000 IU depending on the preparation.
Last Reviewed: 16 August 2002