Low blood levels of vitamin D are tied to bone loss that can lead to falls and fractures. But taking vitamin D supplements in high doses showed no benefits over low-dose vitamin D, a randomized trial found.
The study, in the American Journal of Clinical Nutrition, included 379 British men and women whose average age was 75. They were divided into three groups and given monthly doses of vitamin D, equivalent to 400, 800 and 1,600 IU a day; there was no placebo group. The groups were well matched at the start for vitamin D blood levels, bone mineral density, height, weight, blood pressure and other factors.
Blood levels of vitamin D increased in all three groups in proportion to the dosage. But there was no difference between the groups in changes in bone mineral density, number of falls or number of fractures caused by osteoporosis. At the same time, there were no dose-related adverse events.
It is possible that all three doses limited bone loss, but without a placebo group, that cannot be certain.
“People over 70 should assure they get adequate exposure to vitamin D,” said the lead author, Dr. Terry J. Aspray, a senior lecturer at Newcastle University. “In temperate climates, where we don’t synthesize it for several months, they may need to take supplements. But the arguments for high-dose supplements aren’t supported by this study.”
