Increased Incidence of Vitamin D Deficiency Increases Disease Risk
Vitamin D levels in Americans have plummeted in the last two decades. Vitamin D deficiency, which is the subject of much current research, has been linked to several disease, including multiple sclerosis, particularly pediatric multiple sclerosis. Consequently, in October 2008, the American Academy of Pediatrics doubled the minimum requirement for vitamin D in children. Several studies conducted in the last two years show an association between vitamin D deficiency and heart disease, breast cancer, prostate cancer, osteoporosis, rickets and autoimmune diseases. Studies also show an association between vitamin D deficiency and increased mortality.
Why have vitamin D levels fallen? Researchers suspect that the high concentrations of sunscreens in hand and body lotions, moisturizers, and makeup play a big role in this alarming rise in vitamin D deficiency. Airborne pollution is another factor. People, especially children, are spending more time indoors. With the wider availability of computer games and more television programs geared toward adolescents, playing outdoors is no longer a typical after-school activity. Normally, a 15-minute exposure to sunlight three times weekly would provide adequate vitamin D. Dietary sources of vitamin D are reported to provide about 20 percent of the body’s needs.
In an article published in the March 23 issue of Archives of Internal Medicine, researchers at the University of Colorado School of Medicine in Denver report that nearly 75 percent of all Americans have low vitamin D levels. Vitamin D deficiency is even more pronounced among African-Americans and Hispanics. In this study, Dr. Adit Ginde and his colleagues evaluated vitamin D levels in 18,883 people from blood samples tested between 1988 and 1994, and compared these levels to blood samples from 13,369 people that were tested between 2001 and 2004. All of the blood samples were tested as part of the Third National Health and Nutrition Examination Survey. The evaluation showed that blood levels of vitamin D averaged 30 ng/ml in the 1988-1994 test samples whereas blood levels of vitamin D in the more recent samples averaged 24 ng/ml.
In addition, markedly low levels of vitamin D reported as less than 10 ng/ml were more common in the blood samples from 2001-2004. Among these newer blood samples, fewer people had levels of vitamin D above 30 ng/ml. The reference or optimal levels for vitamin D are 30-40 ng/ml.
In another study published in the December 2, 2008 issue of Arthritis Research & Therapy 2008, Dr. Maurizio Cutolo and his team evaluated vitamin D levels in patients with a variety of autoimmune connective tissue disorders. They found that patients with undifferentiated connective tissue disease (UCTD), a disorder that can resolve or progress into a definitive connective tissue disorder, with low levels of vitamin D were more likely to progress into connective tissue disease, usually rheumatoid arthritis, systemic lupus erythematosus (SLE), Sjogren’s syndrome, and mixed connective tissue disease. The hormone vitamin D is known to have immunomodulatory and anti-inflammatory effects that may play a therapeutic as well as a preventive role in autoimmune diseases.