No one disputes that vitamin D is good for you. The body needs a certain amount of it.
However, whether vitamin D supplements are helpful has been the subject of recent debate. In fact, there is disagreement over whether dietary supplements in general do much at all.
Now, researchers in California are wading into the debate. They say they have found that, contrary to common beliefs, relatively high doses of vitamin D may increase the risk of falls.
The findings are written up in JAMA Internal Medicine.
“There is belief that people should take vitamin D supplements to raise the levels in their blood to an ’ideal’ 30 ng/mL. But a new study shows that this common practice can cause—rather than prevent—falls,” said Dr. Steven Cummings, of the California Pacific Medical Center Research Institute.
Cummings stresses that the combination of vitamin D and calcium supplements has been proven to prevent falls and fractures in older people who live in long-term care facilities or are home-bound. For other people, he says there is no consistent evidence that vitamin D supplements reduce falls or fractures.
The research studied 200 men and women, aged 70 and older, who were living at home with reasonably good cognition and mobility but who had a prior fall. More than half of the seniors had vitamin D concentrations that were below 20 ng/mL, considered by many to be “deficient.”
The study found raising the dosage seemed to have little effect, other than making falls more likely.
“Vitamin D supplementation has been claimed to have many benefits, such as prevention of cancer and heart disease, which have not been supported by clinical trials, Cummings said. “Now we know from clinical trials that relatively high doses of vitamin D supplements might carry a risk.”
The researchers say their findings may be important because doctors sometimes order tests of vitamin D concentrations and recommend supplements to reach a level of 30 ng/mL, as a prevention against falls by older people.
“That target may be too high,” Cummings said. “The Institute of Medicine suggested that a blood concentration of 20 ng/mL is sufficient. However, we need to wait for rigorous randomized trials to show what—if any—dose of a vitamin D supplement or blood concentration of vitamin D has benefits that outweigh risks, especially in older people.”
Until the evidence is clear, Cummings said it is prudent to follow recommendations from the Institute of Medicine. Those recommendations call for people 70 and older to get 800 IU vitamin D daily. Cummings says that doesn’t necessarily mean taking supplements.
“The best sources of vitamin D are sunlight, and foods rich in vitamin D including milk, fortified yogurt, and some types of fish such as salmon and tuna,” he said.