The July 19, 2007 issue of the New England Journal of Medicine published a review authored by renowned vitamin D expert Michael Holick, MD, PhD, which concluded that vitamin D deficiency is widespread although easily prevented. An estimated 1 billion people have levels of the vitamin that are either insufficient or deficient.
Dr Holick, who is 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, introduces his subject by stating that “rickets can be considered the tip of the vitamin D deficiency iceberg.” While reduced levels of the vitamin in utero and childhood can cause growth retardation, skeletal deformities and increased hip fracture risk later in life, a deficiency in adults can result in osteopenia, osteoporosis, muscle weakness, fractures, autoimmune diseases, infectious diseases, cardiovascular disease, and some cancers.
Having insufficient vitamin D means that only 10 to 15 percent of calcium and 60 percent of the phosphorus we consumed are absorbed. Diminished absorption of these minerals is reflected in low bone mineral density, which is associated with fractures, decreased muscle strength, and falls. Individuals living at higher latitudes whose skin is unable to produce adequate amounts of vitamin D have been found to be at greater risk of Hodgkin’s lymphoma, colon, pancreatic, prostate, ovarian, breast, and other cancers.
Fortification of dairy products with vitamin D has helped lower the incidence of rickets, yet Dr Holick believes the current recommended Adequate Intakes for vitamin D need to be increased to at least 800 IU vitamin D3 per day. Greater amounts are needed to treat deficiency states or specific conditions.
“Providing children and adults with approximately at least 800 IU of vitamin D3 per day or its equivalent should guarantee vitamin D sufficiency unless there are mitigating circumstances, he writes. “Unless a person eats oily fish frequently, it is very difficult to obtain that much vitamin D3 on a daily basis from dietary sources. Excessive exposure to sunlight, especially sunlight that causes sunburn, will increase the risk of skin cancer. Thus, sensible sun exposure (or ultraviolet B irradiation) and the use of supplements are needed to fulfill the body’s vitamin D requirement,” he concludes.