People get vitamin D from sun exposure, diet and supplements. Yet vitamin D deficiency is all too common—so common in fact, on expert estimates that 1 billion people in the world have insufficient levels of the much-needed vitamin.
In the July 19 issue of the New England Journal of Medicine, Dr. Michael F. Holick, director of the General Clinical Research Center at Boston University School of Medicine and director of the Bone Healthcare Clinic at Boston Medical Center, published an overview of his work on vitamin D, including his startling estimate.
Because vitamin D plays an important role in the body’s process of absorbing dietary calcium and phosphorous, a lack of the vitamin can have a direct effect on bone mineral density. Without vitamin D, only 10 percent to 15 percent of dietary calcium and about 60 percent of phosphorus is absorbed by the body.
In utero and in childhood, deficiency can cause growth retardation, skeletal deformities and increase the risk of future hip fractures. In adults, too little vitamin D can lead to or exacerbate osteopenia, osteoporosis, muscle weakness and fractures.
Additionally, compelling research has shown that vitamin D may reduce the risk of several medical conditions including common cancers, autoimmune diseases, infectious diseases and cardiovascular diseases.
There is evidence that people who live at higher latitudes—where the angle of the sun's rays is not sufficient to produce adequate amounts of vitamin D in the skin—are more likely to develop and die of Hodgkin's lymphoma, colon, pancreatic, prostate, ovarian, breast and other cancers. There also is an association between low levels of vitamin D and increased risk for type 1 diabetes, multiple sclerosis, Crohn's disease and hypertension.
Holick says that the current recommended intake for vitamin D needs to be increased to 800 to 1,000 International Units (IU) of vitamin D3 daily.
"One can not obtain these amounts from most dietary sources unless one is eating oily fish frequently,” Holick says. “Thus, sensible sun exposure, UVB radiation and/or supplements are required to satisfy the body's vitamin D requirement."
He adds that the goal of his paper is to increase physician awareness of the medical dangers associated with vitamin D deficiency.
“Physicians will then be able to impart this knowledge to their patients so they, too, will know how to recognize, treat and most importantly, maintain adequate levels of this important vitamin," he says.
