“A lot of clinicians are acting like there is a pandemic” of vitamin D deficiency, said Dr. JoAnn E. Manson, a preventive medicine researcher at Brigham
and Women’s Hospital in Boston who helped write an Institute of Medicine report on vitamin D.
“That gives them justification to screen everyone and get everyone well above what the Institute of Medicine recommends.”
In fact, the institute committee on which Dr. Manson served concluded in 2010
that very few people were vitamin D deficient and noted that randomized trials had found no particular benefit for healthy people to have blood levels above 20 nanograms per milliliter.
“A lot of people thought that if they were fatigued or sad or they did not feel well, they might be vitamin D deficient.”
In 2007, Dr. Holick published a paper in The New England Journal of Medicine asserting
that vitamin D levels now considered normal — 21 to 29 nanograms per milliliter of blood — were linked to an increased risk of cancer, autoimmune disease, diabetes, schizophrenia, depression, poor lung capacity and wheezing.
Still, vitamin D has become “a religion,” said Dr. Clifford J. Rosen, an osteoporosis researcher at the Maine Medical Center Research Institute
and a member of the Institute of Medicine’s committee.
Because many people have little exposure to sunlight, especially those living in northern climates in winter, some investigators became concerned more than a decade ago
that large swaths of the population were not getting enough vitamin D.
One is Dr. Michael F. Holick, a professor of medicine, physiology and biophysics at Boston University School of Medicine and a leading proponent of the idea
that just about everyone needs a vitamin D supplement.