Other research suggests it’s time to ditch the vitamin D craze.
Taking high doses of the “sunshine vitamin” does not reduce the risk of fractures in generally healthy older Americans, researchers reported Wednesday.
It’s the latest in a string of disappointments about a nutrient once hoped to have far-reaching protective effects. That same study of nearly 26,000 people had previously found that taking lots of vitamin D pills also didn’t prevent heart disease, cancer, or memory loss.
And while getting enough vitamin D is important for strong bones, “more isn’t better,” said Dr. Meryl LeBoff of Brigham and Women’s Hospital Boston, lead author of the study.
An estimated one-third of Americans 60 and older take the supplements, and more than 10 million blood tests for vitamin D levels are performed each year – despite years of controversy over whether the average adult need one or the other.
The most recent findings — added to other trials with similar results — should end that debate, wrote Drs. Steven Cummings of California Pacific Medical Center and Clifford Rosen of Maine Medical Center Research Institute in a medical journal commentary.
“People should stop taking vitamin D supplements to prevent major illnesses” – and doctors should stop the routine screenings that fuel concerns, the two men concluded. They did not participate in the last study.
How much vitamin D should people consume? The United States recommends 600 to 800 international units per day to ensure that everyone, young and old, gets enough. Although our skin makes vitamin D from sun exposure, it can be more difficult in the winter. Milk and some other foods are fortified with the nutrient to help.
The bigger question was whether more than the recommended amount might be better, for preventing fractures or perhaps other disorders as well. To respond to conflicting scientific reports, Brigham and Woman’s Chief of Preventive Medicine, Dr. JoAnn Manson, launched the largest study of its kind to track a variety of health outcomes in nearly 26,000 generally healthy Americans. in their fifties or older. The latest results compare bone fractures in those who took a high dose – 2,000 international units of the most active form of vitamin D, called D-3 – or dummy pills every day for five years.
The supplements did not reduce the risk of broken hips or other bones, LeBoff reported in the New England Journal of Medicine. Although vitamin D and calcium work better together, she said even the 20% of study participants who also took a calcium supplement did not benefit. Neither did the small number of study participants who had low blood levels of vitamin D.
Still, LeBoff cautioned that the study did not include people who may need supplements due to thinning osteoporosis or other disorders, or those with severe vitamin D deficiencies. And Manson said that more research was needed to determine if there are other high-risk groups that might benefit.
Overall, “these findings overturn dogma and cast doubt on the value of routine screening for vitamin D blood levels and general recommendations for supplementation,” Manson said. “Spending time outdoors, being physically active, and eating a heart-healthy diet will lead to greater health gains” for most people.
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