Vitamin D is such an important nutrient—and one that is backed by a growing body of positive research—that we wanted to hear another perspective on this latest study. Taylor Wallace, senior director of scientific and regulatory affairs at the Council for Responsible Nutrition, says the findings of this study have been overstated and that—in most cases—supplementing with vitamin D is perfectly safe. “I see the conclusions going a little too far beyond what the data really says,” he says.

Study design 

Wallace particularly takes issue with the way the researchers compiled their statistics, noting that one group (the low–vitamin D group) contained far more minorities, overweight people and smokers—a fact that could have skewed results.

Safe upper limit 

He also notes that the National Academy of Sciences has determined 4,000 IUs daily to be a safe upper limit of vitamin D for adults. However, he sees little scientific reason to take more than 2,500 to 3,000 IUs daily, unless your doctor recommends a higher dose. “I am very supportive of consumers supplementing with D—probably more so than any vitamin,” he says. “It is a very safe supplement, and many of us are deficient in it.”