Air Pollution Compromises Vitamin D Status

Atmospheric pollution, by blocking some of the ultraviolet rays of the sun, can promote the development of vitamin D deficiency, according to a report in Archives of Disease in Childhood (2002;87:111–3).

Severe vitamin D deficiency in children can cause rickets, which leads to permanent deformities of the bones. In adults, severe vitamin D deficiency results in softening of the bones (osteomalacia) and muscle weakness. A milder deficiency of the vitamin can lead to impaired balance, possibly increasing the risk of falling down. In one study, elderly individuals who received a vitamin D supplement (800 IU per day) fell down 47% less often over a one-year period than did those who received a placebo.

In the new study, blood levels of vitamin D were measured in two areas of Delhi, India: one with high levels of air pollution and the other with significantly less pollution. The average vitamin D concentration was 54% lower in the former than in the latter. Forty-six percent of the children in the heavily polluted area had subnormal blood levels of vitamin D and in 12% of the children the deficiency was severe enough to cause rickets. In contrast, none of the 31 children living in the less polluted area had vitamin D deficiency.

Vitamin D is present in only a few foods (e.g., cod-liver oil, egg yolks, and vitamin D-fortified dairy products); most of the vitamin D in the body is produced by a chemical reaction in the skin triggered by exposure to sunlight. People who do not receive adequate amounts of sunlight are at increased risk of developing vitamin D deficiency. Factors that might promote a deficiency include staying indoors, covering one's body when outside, and having dark skin (which filters the sunlight). In addition, people who live at high latitudes receive less sunlight and therefore have a higher incidence of vitamin D deficiency, compared with those who live closer to the equator.

Vitamin D deficiency is more common than most people realize, occurring in up to 40% of healthy people in some studies and in more than half of hospital patients on a general medical ward.

It does not take a lot of sunlight exposure to prevent vitamin D deficiency. Experts recommend that an elderly person living in a climate with less sun exposure (such as Boston) receive 5 to 30 minutes of sunlight per day, depending on their skin sensitivity. In areas where the sun is stronger (such as Florida), even less exposure time can do the job. Adults who are unable to go out in the sun may benefit from a vitamin D supplement in the amount of 200 to 1,000 IU per day. Long-term supplementation with more than 1,000 IU per day should be supervised by a doctor. The Recommended Dietary Allowance of vitamin D for children is 200 IU per day.

Alan R. Gaby, MD, an expert in nutritional therapies, testified to the White House Commission on CAM upon request in December 2001. Dr. Gaby served as a member of the Ad-Hoc Advisory Panel of the National Institutes of Health Office of Alternative Medicine. He is the author of Preventing and Reversing Osteoporosis (Prima, 1994), and co-author of The Natural Pharmacy, 2nd Edition (Healthnotes, Prima, 1999), the A–Z Guide to Drug-Herb-Vitamin Interactions (Healthnotes, Prima, 1999), Clinical Essentials Volume 1 and 2 (Healthnotes, 2000), and The Patient’s Book of Natural Healing (Prima, 1999). A former professor at Bastyr University of Natural Health Sciences, in Kenmore, WA, where he served as the Endowed Professor of Nutrition, Dr. Gaby is the Chief Medical Editor for Healthnotes, Inc.

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