Vitamin D is in some respects a little different from other vitamins in that it can be made in the skin from precursor substances when exposed to sunshine. The problem is that in the northern and southern extremes sunshine is not intense enough for some four to five months each year.
In Canada, for example, vitamin D levels are very low and, consequently, fortification of many foods has been undertaken.
The concern with vitamin D reflects more than fears about rickets. We now believe vitamin D plays a role in osteoporosis and a variety of cancers, including prostate cancer. In addition, we are concerned because vegetarians may be at increased risk because they do not get the vitamin D present in animal products.
Fear of skin cancer has also led to the use of ultraviolet (UV) blocking creams, lotions, and sprays, which also cuts the production of vitamin D. As well as the time and intensity of sunlight exposure, however, the amount of skin exposed is also important. We are not advocating nudism, of course, but exposure to the sun of more of our skin would result in greater production of vitamin D.
In a breakdown of some data gathered in the Adventist Health Study II, Dr. Jacqueline Chan, a professor in the Loma Linda University School of Public Health, has shown low serum vitamin D levels in all the Adventist groups studied. This was in vegans, lacto-ovo vegetarians, meat eaters, and both African-Americans and Caucasians. The studies also show that African-Americans need more sunlight than do Caucasians.
Because vitamin D may play a role in up to 16 different cancers, diabetes, heart disease, and osteoporosis, it is probably important for all of us to get our vitamin D levels measured. Even people living in sunny areas often have low vitamin D levels because of the type of work they do and the clothing they wear.
This is a global problem, and we all need to pay attention to increasing our vitamin D intake. The recommendations of vitamin D intake used to be 400 IU (international units), or 10 micrograms, per day. Recently, these recommendations have been doubled, and many specialists are now suggesting as much as 2,000 IU per day.
Vitamin D deficiency is more than a problem for vegetarians—it involves the whole gamut of dietary practices and spans the globe.
Where possible, exposure of a large area of the body to some 20 minutes of midday sunshine would be the natural way of getting vitamin D; this being impractical for most, supplementation is recommended. We recommend individuals should supplement their vitamin D intake to at least a level of 1,000 IU a day, in addition to consuming vitamin D-fortified products and getting a little sunshine each day.
Allan R. Handysides, M.B., Ch.B., FRCPC, FRCSC, FACOG, is director of the General Conference Health Ministries Department; Peter N. Landless, M.B., B.Ch., M.Med., F.C.P.(SA), F.A.C.C., is ICPA executive director and associate director of Health Ministries.
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