= Full article availableVitamin D has been shown to reduce the risk of bone fractures in the elderly—but is the Recommend Dietary Allowance (RDA) of vitamin D enough to do the job? A recent review of the research on vitamin D and fractures, published in the Journal of the American Medical Association (JAMA), concluded that the answer is no.
The RDA of vitamin D for older adults is between 400 and 600 International Units (IU) per day. In their meta-analysis of seven experimental trials, a team of scientists including senior author Bess Dawson-Hughes, MD, director of the Bone Metabolism Laboratory at Tufts’ Jean Mayer USDA Human Nutrition and Research Center on Aging, found that this dose was not effective in reducing nonvertebral fracture rates among study participants. The researchers concluded, however, that higher daily doses of vitamin D—in the range of 700 to 800 IU—may reduce the risk of fracture by approximately 25%.
The experimental trials all compared fracture rates among subjects 60 years of age and older who were given vitamin D supplements (with or without calcium supplements) with fracture rates among similar subjects who were given only calcium or a placebo. Each study lasted between one and five years, and looked specifically at hip fractures or other fractures that did not involve the spine. The review of these trials found that only subjects receiving higher doses of vitamin D supplementation had significantly fewer fractures than did subjects in the comparison groups.
With an aging population and with people living longer, experts say bone fractures will become a bigger and more costly problem unless more is done to prevent them. Osteoporosis (reduced bone mineral density) is most common in older adults, particularly women. It is a major risk factor for bone fractures, which can cause significant suffering while carrying high economic costs.
“In the future, we may need to reconsider the current recommended daily values of vitamin D for older adults,” says Dr. Dawson-Hughes. “We also need to look more closely at the possible role that calcium supplementation may have in mediating the effects of vitamin D. Fractures in the elderly can lead to severe health consequences, including death. One promising prevention strategy may be dietary supplementation with both calcium and vitamin D.”
How does vitamin D help strengthen bones? “Vitamin D promotes the absorption of dietary calcium,” Dr. Dawson-Hughes explains. “You need an adequate vitamin D level to make use of the calcium.”
Unlike calcium, though, it’s difficult to get enough vitamin D from dietary sources alone. But don’t try taking “extra” multivitamins, which will give you too much vitamin A, among other problems. Instead, Dr. Dawson-Hughes suggests combining a multivitamin containing 400 IU with an inexpensive vitamin D supplement that also has 400 IU.
Another meta-analysis on vitamin D published in JAMA last year found that older adults can reduce their risk related to falls by more than 20% by making sure they get enough vitamin D. Dr. Dawson-Hughes, also an author on that paper, noted that “vitamin D may also improve muscle strength, thereby reducing fracture risk through fall prevention.”
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