The findings and accompanying editorial by Dr. Cummings and colleagues were published online 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. Cummings, Director of the San Francisco Coordinating Center, commenting on a recent randomized trial by researchers at the University Hospital Zurich, Switzerland.
Dr. Cummings emphasized 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, there is no consistent evidence that vitamin D supplements reduce falls or fractures.
The Swiss study—designed to determine whether doses of vitamin D that achieved blood concentrations of 30 ng/mL improve strength and balance—studied 200 men and women (aged 70 years 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.” Two doses (60,000 IU of vitamin D3 monthly or 24,000 IU vitamin D3 plus 300 μg of calcifediol monthly, equivalent to about 2,000 IU daily) achieved the goal of 30 ng/mL in 80% of study participants—a level that has been recommended as best for reducing the risk of fractures and for other health benefits. However, compared with a monthly dose of 24,000 IU vitamin D3 (equivalent to 800 IU daily), the higher doses had no effect on physical performance and instead increased the risk of falls.
“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 (the strongest type of evidence). Now we know from clinical trials that relatively high doses of vitamin D supplements might carry a risk.”
Doctors sometimes order tests of vitamin D concentrations and recommend supplements to reach that level of 30 ng/mL. “That target may be too high. 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,” said Dr. Cummings.
“Until we have that evidence, it is prudent to follow recommendations from the Institute of Medicine that people aged 70 years and older get 800 IU vitamin D daily. The best sources of vitamin D are sunlight, and foods rich in vitamin D including milk, fortified yoghurt, and some types of fish such as salmon and tuna.”
Source Newsroom: California Pacific Medical Center Research Institute
JAMA Internal Medicine, January 4, 2016