For some time we have suspected that high levels of vitamin A intake may harm our bones. A new study published in the Journal of the American Medical Association in early January 2002 has now strengthened this negative link. Scientists (D. Feskanich et al., JAMA 287(1): pages 47-54, 2002) from the Harvard School of Public Health in Boston have been following a cohort of over 121,700 women for 26 years. The study is one of the largest of its kind and is called the Nurses’ Health Study. In this most recent analysis of the data, the scientists examined the relationship between vitamin A intake and hip fractures in 72,000 of the women. The women ranged in age from 34 to 77. The results of the study showed that 603 hip fractures were experienced by the women between 1980 and 1998. The women taking in the highest amount of vitamin A had a 48% increased risk of having a hip fracture while the women taking in the lowest amount of vitamin A had the lowest risk for hip fracture.

What does this mean in terms of guidance for vitamin A intake? In industrialized countries vitamin A deficiency is rarely a problem (although in developing countries, vitamin A deficiency is the leading cause of blindness). Beta-carotene found in healthy fruits and vegetables can easily be converted into vitamin A to meet our needs. Fortunately, there isn’t any negative link between beta-carotene and bone health. We also get vitamin A from liver, milk and fortified breakfast cereals. In the Nurses’ Health cohort, the women who were at increased risk for hip fractures were getting 2,250 micrograms or more/day-this amount is less than the tolerable upper limit of 3,000 micrograms/day set by the National Academy of Sciences (the recommended amount is 700 micrograms/day).

My advice is to make sure you aren’t getting too much vitamin A from your diet or supplements. Don’t eat too much liver and if possible, choose a breakfast cereal that isn’t fortified with vitamin A (beta-carotene is okay). Also, make sure that your multivitamin does not contain vitamin A-again, beta-carotene is fine. Retinol is the most common source of vitamin A used to fortify foods and vitamin supplements. Currently, it is difficult to find a multivitamin supplement that does not contain vitamin A, although I suspect that in the near future pharmaceutical companies will be offering such options. In the meantime, you might have to do a little hunting to find the right multivitamin. And don’t forget to take a calcium and vitamin D supplement to help your bones!