Vitamin D: New Roles for an Old Vitamin
Written by Debra Kirchhof-Glazier
Everyone knows that vitamin D is important in helping us absorb calcium, making it good for our bones. In fact, many of us take calcium supplements with added vitamin D to protect ourselves from osteoporosis. But did you know that recent research strongly suggests a crucial role of vitamin D in our immune systems?
Vitamin D is a fat-soluble vitamin made in the body by a complex process that begins with exposure of the skin to ultraviolet rays from the sun, which forms a precursor molecule that is changed to the active state by the liver and kidneys. Most of us need to obtain vitamin D from our diets, as sun exposure is limited by our modern lifestyles spent mostly indoors and by use of sunscreens with protection factors of 8 or more, which block the ultraviolet rays that form vitamin D. One of the richest dietary sources of vitamin D is cod liver oil. Other sources include salmon, tuna, egg yolk, and milk fortified with vitamin D.
Dr. Margherita Cantorna at Penn State University has conducted extensive studies that strongly suggest vitamin D can decrease the prevalence of some autoimmune diseases. For example, Dr. Cantorna found that mice deficient in vitamin D or lacking the receptors for the vitamin were more susceptible to inflammatory bowel disease, which in humans includes conditions like Crohn’s disease and ulcerative colitis. Supplementation of the active form of vitamin D stopped the progression of the disease or completely prevented it. In humans, treatment for inflammatory bowel disease usually involves steroids, which can lead to bleeding and bone loss. Supplementation with vitamin D, which also has anti-inflammatory properties, could thus allow a lowering of the dose of the steroids to minimize their side effects.
Vitamin D also apparently has a role in preventing multiple sclerosis. Dr. Cantorna found that vitamin D deficiency increased the susceptibility of mice to multiple sclerosis, whereas supplementation of the active form prevented the development of the condition. It is interesting to note that multiple sclerosis in human populations is more prevalent at lower altitudes and at increasing distances from the equator, where ultraviolet light is less intense and vitamin D production by the skin is much lower. It is an exciting prospect to investigate the possibility that supplementation of vitamin D may help prevent the development of multiple sclerosis in people genetically prone to this disease.
Although this sounds wonderful, especially to sufferers of multiple sclerosis and inflammatory bowel diseases, it is not a good idea to rush out and start supplementing with vitamin D without the supervision of a health professional or nutritionist. Excessive doses can lead to muscle weakness, high blood pressure, high cholesterol and irregular heart rate. Chronic overdose can cause calcium deposits in the kidneys, blood vessels, lungs, skin, and heart, with wide individual variation in dosages that cause toxicity. On the other hand, there is recent evidence to suggest that the 400 IU (international units) that has been the standard recommendation for many years may be less than optimal. Articles in the supplement of the 2004 edition of the American Journal of Clinical Nutrition point out that it may be more appropriate to recommend 1000 IU days for adults.
“You are what you eat” is the axiom that sums up the importance of the quality of our food. When it comes to vitamin D, we are beginning to find that it does far more than we originally thought. This is undoubtedly the case with many other nutrients. We are beginning to appreciate that the science of nutrition is as important as the science of pharmacology in both preventing and treating disease. I feel certain that someday in the not too distant future, healing with foods and nutrients will become as prevalent as healing with medications in the emerging field of integrative medicine.
The Huntingdon Health and Wellness Association makes no medical claims or recommendations. Check with your doctor about your specific health care needs.