Sun Exposure - for Vitamin D and other Benefits
Summer is in full throttle and we should be spending time in the sun! The idea that sun exposure is dangerous and increases the risk of cancer has convinced some people that ALL sunshine should be avoided, and that vitamin D supplements are a viable substitute. Unfortunately, the research says otherwise.
Vitamin D is unusual in two ways. First, it is actually a hormone and not a vitamin, and second, we get it primarily from exposure to sunlight rather than from eating food. How much vitamin D do we need? The Scientific Advisory Committee on Nutrition, and the National Institutes of Health, both recommend 200 International Units (IUs) per day, which is easily obtainable through brief exposures to sunlight – without the use of sunscreen – and is a far cry from the recommended levels of 2,000-4,000 IU’s/day. Many doctors agree that the current standards are too high.
How does it work? As your skin soaks up ultraviolet sunlight, it produces vitamin D with the help of the liver and kidneys. The average person living in the US produces about 90% of their vitamin D from sunlight, and only about 10% from food or supplements. Your body stores extra vitamin D during the sunniest months, and slowly releases it during the darker months.
For Caucasians, wearing a bathing suit in the sun for 20 to 30 minutes at one time – without sunscreen - provides between 20,000 – 30,000 UIs of vitamin D; however, exposing only the hands, face and arms to noontime sun for only 5 minutes, 2 to 3 times per week, is plenty for light-skinned people. People of Asian or Indian descent may require three times as much sun, and those of African descent may need up to ten times in order to produce enough vitamin D.
Why should we get some sun without using sunscreen? Dr. Michael Hollick, Ph.D., M.D., reminds us that a sunscreen with SPF of 8 reduces the ability of the skin to make Vitamin D by 92.5%. Sunscreen with SPF 15 reduces it by 99%. Dr. Hollick agrees with the common medical assessment that somewhere between 30 and 80% of the American population is Vitamin D-deficient; he also agrees with the research showing that people with lower Vitamin D levels are at higher risk of developing many conditions, including cancer. However, he does not recommend the use of supplements, fortified foods and oily fish to compensate for this deficiency.
While burning of the skin is harmful and should always be avoided, getting at least 15-20 minutes of unprotected sun is healthful in many ways. For example, according to a World Health Organization report, the risk of sun cancer as a result of sun exposure has been over-exaggerated. The report stated that a much larger annual disease burden likely results from LOW levels of sun exposure, since sun avoidance leads to increased risk of conditions like autoimmune diseases and other types of cancer.
Other studies (which I’m happy to forward to you upon request), show that not only can sunlight reduce the risk of inflammation and autoimmune diseases, it can inactivate viruses (including those that cause chicken pox and shingles); it can also stimulate the production of nitric oxide, which protects the cardiovascular system and reduces the risk of heart attack and stroke. And because sunlight stimulates neuroendocrine and immune system functions, MS patients who had sun exposure had less neurodegeneration and greater whole brain volume that those who took vitamin D supplements.
What about supplements? Vitamin D supplements may actually increase your risk for certain diseases due to nutritional imbalances and should be considered as the last resort. Even dosages which are considered “safe” have been shown to contribute to increased LDL cholesterol, certain cancers, immune system suppression, kidney disease, gastrointestinal issues, and may actually hurt bones. But for those who must take Vitamin D supplements, such as the elderly who are unable to get outdoors, 200 UIs per day should be adequate according to Dr. John McDougall.
So get out there and build up your skin’s tolerance to the sun. Remember that sunburns ARE dangerous, and that safe sun exposure is the key. Start with limited exposure – enough to lightly tan but not burn - and gradually increase your exposure until you can spend an hour or two in the sun. Once you reach your maximum tolerance, cover up or sit in the shade. Use sunscreen only for those times when you must be exposed to the sun for long periods.