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More Than Just a Way to Regulate Calcium  |
Now that its role in calcium uptake had been sketched out, researchers in the 1970s began investigating vitamin D in greater detail--and with surprising results. Several groups managed to find the vitamin D hormone in the nucleus of cells that were not part of the classical calcium maintenance system including the brain, lymphocytes (infection fighting white blood cells), skin, and malignant tissues. What business would vitamin D have in these places?
In the early 1980s, Japanese researcher Tatsuo Suda made the exciting discovery that adding the hormone to immature malignant leukemia cells caused the cells to differentiate, mature, and stop growing. The amount of vitamin D hormone needed to stop the runaway growth of tumors and cancers has so far proved too toxic for human use, but Suda's discovery suggested that this fascinating hormone had roles beyond the part it played in maintaining the body's calcium levels. This finding spurred on a new era in vitamin D research.
In the mid 1980s, a group of researchers led by S. C. Manolagas found that vitamin D hormone also seemed to play a part in modulating the immune system. In 1993, S. Yang and other researchers in DeLuca's laboratory found that rats given a large dose of vitamin D hormone were protected from the inflammation normally associated with wounds and chemical irritants. This unexpected immunosuppressant function for vitamin D hormone suggested a whole new range of possibilities--including its use in the control of autoimmune diseases.
More developed is vitamin D hormone's effect on psoriasis, a disfiguring skin disorder that affects some 50 million people worldwide. For reasons unknown, psoriasis causes skin cells to multiply uncontrollably. Failing to differentiate and develop normally, the skin cells clump in unsightly rashes, scales, and scars. In the 1980s, a Japanese research team demonstrated that 1,25-dihydroxyvitamin D3 can inhibit skin cell growth. A team of scientists at Boston University School of Medicine, led by Michael F. Holick, investigated this inhibition further and reasoned that it could be used for the treatment of psoriasis.
Initial experiments by Holick and coworkers with vitamin D hormone have shown that topical applications of the hormone are remarkably effective. After two months, the lesions of 96.5 percent of the patients treated with a topical calcitriol (vitamin D hormone) preparation had improved with no noticeable side effects, as compared with 15.5 percent of the controls treated with petroleum alone. In 1994 the U.S. Food and Drug Administration approved a vitamin D--based topical treatment for psoriasis, called calcipotriol.
 As we enter the twenty-first century, we recognize that the basic scientific research done in the previous two centuries has not only untangled the workings of the elusive vitamin D hormone, but also and has given us ways to protect the health of both adults and children. Researchers are pursuing many new applications for vitamin D, but its role in building and maintaining bone continues to be an important health issue, especially among middle-aged and older adults.
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 | | | About Vitamin D - This page from the University of California, Riverside is worth an in-depth look. The site offers an overview of Vitamin D's history, nutritional aspects, and its chemistry and biochemistry. |  | | Food & Nutrition Information Center - Great resource with links to information on dietary guidelines, dietary supplements, food composition, and more. | | | Food Science and Nutrition Resources on the Web - This site offers a guide to web resources in food science and nutrition, including biochemical
& biophysical properties of foods & their constituents. | | | Nutrition Insights - Articles from the USDA Center for Nutrition Policy and Promotion available in PDF format. The articles cover a wide range of topics. |  |
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