What is known is that many of us don’t get enough. A 2010 study in Nutrition Journal found that 42 percent of U.S. adults were deficient in Vitamin D, with the highest rates among African Americans and Hispanics.
Children are also at risk: A report in the Archives of Pediatric and Adolescent Medicine showed that 12 percent of children had Vitamin D deficiencies, and an additional 40 percent exhibited higher but still insufficient levels.
“Vitamin D, working with calcium, is very clearly critically important for bone health, particularly in youth during skeletal development up through puberty and . . . in your 50s, 60s and beyond, for the prevention of osteoporosis, fractures and falls,” said Steven Clinton, a professor of medical oncology at Ohio State University. Clinton recently served on an Institute of Medicine committee charged with reviewing Vitamin D intake recommendations.
Additionally, in the last year alone, numerous published studies have concluded that Vitamin D might play a role in preventing everything from cancer and cardiovascular disease to Alzheimer’s, diabetes, depression,
and weight gain.
This research, however, has not convinced everyone.
“Yes, there are some observational studies suggesting that men and women who have higher blood levels of Vitamin D have a lower risk of cancer, heart disease, diabetes and other health problems, but . . . these results may be due to other, confounding factors,” said JoAnn Manson, chief of preventive medicine at Harvard-affiliated Brigham and Women’s Hospital, who served on the IOM committee.
She hopes to provide some answers as principal investigator of the first large-scale, randomized clinical study on the effect of moderate to high doses of Vitamin D on cancer, cardiovascular disease and a range of other conditions.
For now, the IOM recommends 400 international units of dietary Vitamin D a day for babies up to a year, then 600 IU up to age 70, with 800 IU for those older than 70, in order to maintain a blood level of at least 20 nanograms per milliliter. That amount is considered optimal for bone health for most people.
Manson noted that this assumes minimal sun exposure and added that people with osteoporosis and those who are obese or who have malabsorption or other medical problems might require more, and should consult with their doctors.
Clinton said that while he is convinced that Vitamin D could decrease susceptibility to cancer, “we really do not have the kind of information we need yet to tell someone what blood level of Vitamin D you should have at what stage of your life to clearly impact your risk of developing any of some 100 different kinds of cancer people get. We have an enormous amount left to learn, and need more research to help us sort this out.”