There are drawbacks from getting vitamin D from foods and from the sun. So which one is has lesser consequences?
Scientists agree that sufficient vitamin D is needed for you to maintain good health, and the primary source of vitamin D occurs when your skin is exposed to the sun's UV rays. Given the threats those same UV rays pose to your skin, many scientists—including those at the Skin Cancer Foundation—are reluctant to recommend allowing skin to be exposed to the sun without a broad-spectrum sunscreen, which blocks those UV rays. Public awareness of the need to protect skin is growing, along with another alarming fact: at least one-third to half of all Americans are deficient in vitamin D. Is it possible that the steps we take to defend against skin cancer are causing another health problem?
Vitamin D deficiency can lead to weak bones and skeletal malformations, osteoporosis, cardiac problems, auto-immune diseases, and even cancer. New research is revealing just how critical this vitamin may be, and many doctors are now reversing their earlier opinions that any sun exposure is bad. Under ideal conditions, it only takes about 10 to 15 minutes of daily sun exposure to produce sufficient quantities of vitamin D for people with fair skin. Seniors and people with dark skin require longer periods of exposure. Seasonal, weather, and geographical factors also play a big role since Americans at high altitudes or in cloudy or polluted areas will need longer periods of time in the sun for their skin to synthesize enough vitamin D.
Few foods provide vitamin D, but you can find it in fatty fish like salmon and mackerel and in cod liver oil. It's also present in small quantities in egg yolks and cheese, and in food that has been fortified with vitamin D like milk, orange juice, and cereals. Supplements are also available, though multi-vitamins typically only supply 400 International Units daily. Older guidelines have thought this would be sufficient, but many doctors like those from Harvard Health Publications believe the average person should get 800 to 1000 International Units. The alarming rise in people who are vitamin D deficient clearly shows that we need more than we're currently getting.
Sunscreen with an SPF of eight or more can entirely block your bodies' ability to absorb vitamin D, as does hanging out in the shade. This is why skin cancer prevention guidelines—which warn you should never go outside without sunscreen—and recommendations from vitamin D researchers are at odds. For some people, it may be possible to strike a balance by allowing some sun on their arms and legs at certain times of the day, while always protecting their face. However, this approach would not work for those with a high risk of skin cancer. Look to your doctor for a personal recommendation that will keep you healthy.
Sources:
Health.harvard.edu: "Time for More Vitamin D." Harvard Health Publications: Harvard Medical School. Web. September, 2008.
http://www.health.harvard.edu/newsweek/time-for-more-vitamin-d.htm
Mayoclinic.com: "Vitamin D." Mayo Clinic. Web. October 1, 2011.
http://www.mayoclinic.com/health/vitamin-d/NS_patient-vitamind
Skincancer.org: "The Skin Cancer Foundation Statement on Obtaining Adequate Vitamin D." Skin Cancer Foundation. Web. 2011
http://www.skincancer.org/healthy-lifestyle/vitamin-d/the-skin-cancer-foundation-statement-on-obtaining-adequate-vitamin-d
