Boston University - A review article on vitamin D just released by Dr. Michael Holick, an internationally recognized expert in vitamin D, provides an overview of his pioneering work that expounds on the important role vitamin D plays in a wide variety of chronic health conditions, as well as suggesting strategies for the prevention and treatment of vitamin D deficiency. The vitamin D review appears in the July 19, 2007 issue of the New England Journal of Medicine.

People obtain vitamin D from diet, supplements, or most commonly, exposure of the skin to the ultraviolet wavelengths of sunlight. Vitamin D deficiency is common in children and adults. In the womb and in childhood, vitamin D deficiency may cause growth retardation, skeletal deformities and increase risk of hip fractures later in life. In adults, vitamin D deficiency may precipitate or exacerbate osteopenia, osteoporosis, muscle weakness, fractures, common cancers, autoimmune diseases, infectious diseases and cardiovascular diseases.

According to Holick, a professor of medicine, physiology, and biophysics, and director of the General Clinical Research Center at Boston University School of Medicine and Director of the Bone Healthcare Clinic at Boston Medical Center, it has been estimated that 1 billion people world-wide are vitamin D deficient or insufficient.

Without vitamin D only about 10 to 15 percent of dietary calcium and about 60 percent of phosphorus is absorbed by the body. Low vitamin D levels thus reduce bone mineral density which can contribute to osteoporosis and fractures, as well as muscle weakness and falls in adults. In the womb and in childhood, calcium and vitamin D deficiency prevents the maximum deposition of calcium in the skeleton.

Studies have shown people living at higher latitudes (where the angle of the sun’s rays leads to inadequate vitamin D production in the skin) are more likely to develop and die of Hodgkin’s lymphoma, colon, pancreatic, prostate, ovarian, breast and other cancers. According to Holick, both prospective and retrospective epidemiologic studies have also shown an association between low levels of vitamin D and an increased risk for Type 1 diabetes, multiple sclerosis, Crohn’s disease, hypertension and cardiovascular disease.

Holick believes the current recommended adequate intakes for vitamin D need to be increased to 800 to 1000 IU vitamin D3 per day. (Vitamin D3 is the preferred form of vitamin D, as it is the form of vitamin D made by the skin and thus is most natural to humans. Vitamin D2 added to some vegetarian products such as soy milk is not the same.) “However, one cannot obtain these amounts from most dietary sources unless one is eating oily fish frequently,” says Holick. “Thus, sensible sun exposure (or UVB irradiation) and/or supplements are required to satisfy the body’s vitamin D requirement,” he adds.

Lastly Holick adds, “The goal of this paper is to make physicians aware of the medical problems 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,” that is, vitamin D3 (Courtesy of EurekAlert!, a service of AAAS).