Vitamin D supplementation and sun exposure: Can we pick and choose?

Posted on July 11, 2012 by John Cannell, MD.

Despite the increased risk of non-melanoma skin cancers, the Vitamin D Council recommends moderate sun exposure and 5,000 IU of vitamin D3 on days you do not get sun exposure. We are not alone. Recent studies imply that sun exposure does more than simply make vitamin D and that one cannot fully replace the benefits of sun exposure by simply taking a vitamin D supplement.

Dr. Prue Hart of the University of Western Australia makes these points in a recent paper.

Hart PH. Vitamin D supplementation, moderate sun exposure, and control of immune Diseases. Discov Med. 2012 Jun;13(73):397-404...................
http://www.ncbi.nlm.nih.gov/pubmed/22742645


She contends that sunshine affects the immune system via non-vitamin D mechanisms as well as vitamin D mechanisms by citing both human and animal studies. She argues, “It is possible that moderate sun exposure and vitamin D supplementation may be complementary for maximal control of immune-driven diseases.”

She also points out that over the last two decades vitamin D levels have fallen about twenty percent while the incidence of immune system diseases, such as multiple sclerosis, type 1 diabetes, and asthma have all increased during that same time period. Dr. Hart cited evidence that vitamin D is crucial to brain functioning and added autism as a vitamin D/sunshine related disease. She predicts, “Within ten years, we should have a clearer answer from randomized controlled studies as to whether vitamin D per se can reduce the incidence and progression of immune diseases, cardiovascular disease, autism, and more.”

In regards to sun exposure recommendations, Hart stated, “Repeated short sun exposures to a larger body surface area are likely to have a greater effect than longer exposures of smaller areas.” Of course, few of us are in a situation that allows large surface area exposures every day. However, weekends and holidays offer the opportunity of nearly full body short sun exposures for both adults and children. On the days one gets such exposure, there is no need to take oral vitamin D supplementation.

Ten years is a long time to wait for the randomized controlled trials that many believe will settle the vitamin D issue. During those ten years, it seems wise to protect you and your family with at least some moderate sun exposure combined with adequate daily doses of vitamin D3 on sunless days.


About John Cannell, MD
Dr. John Cannell is founder of the Vitamin D Council. He has written many peer-reviewed papers on vitamin D and speaks frequently across the United States on the subject. Dr. Cannell holds an M.D. and has served the medical field as a general practitioner, itinerant emergency physician, and psychiatrist. Tweet