AFTER SCARING US AWAY FROM THE SUN FOR A GENERATION, THERE ARE NEW INSIGHTS ABOUT HOW MUCH SUNLIGHT IS HEALTHY.
Some forms of hair loss can be tied to nutrient deficiencies, including having an inadequate amount of vitamin D. But more medically serious conditions – heart disease, cancers, autoimmune diseases and osteoporosis – also are tied to vitamin D deficiencies. Researchers estimate that about half the U.S. population is not getting enough vitamin D, such that they’re now telling us we need to spend more time in the sun.
What? After all these years of warnings against sun exposure, we can go out and get a tan after all?
Well, not exactly. Michael Holick, M.D., Ph.D., director of both the Vitamin D, Skin, and Bone Research Laboratory and Biologic Effects of Light Research Center at Boston University Medical Center, spends a great deal of time studying this phenomenon. He believes there is a vitamin D deficiency pandemic and that the solution is sun exposure on the legs and arms for ten minutes, three times per week (still preserve your face with sunscreen).
If you’re mad about this, you have a right to be. The dermatologists and cancer prevention specialists have been scaring us away from the beach and promoting SPF lotions for a generation. Now, Holick and other researchers’ findings seem to fly in the face of our worries about skin cancer and premature aging, and those anti-sun forces are conceding this counteropinion. It looks to be a situation where both “too much” and “too little” approaches cause their own set of problems. We have to hit it just right.
How much Vitamin D do we really need?
According to Marcy Holmes, NP, a certified menopause clinician who writes for WomenToWomen.com, inadequate amounts of vitamins D and A, as well as iron and protein, can cause alopecia. She notes that fish oil supplements containing vitamin D and essential fatty acids can address this.
But Dr. Holick says his and other studies show it’s very hard to get adequate amounts of vitamin D from dietary sources alone. This has to do with different forms of the vitamin. Vitamin D2 is sourced from fortified milk, cereals and in some supplements; D2 is less utilized by the body than is vitamin D3, which is manufactured by our bodies through sun exposure and is therefore more bioavailable (D3 is also available in supplement form). Both versions of the vitamin affect calcium absorption in the gut, balancing serum calcium and phosphate concentrations, which in turn affect bone health, among other biological functions.
But the human body needs about 200 international units (IUs) daily up to the age of 50, after which time that amount should double (400 IUs) and triple after the age of 70 (600 IUs); no toxicity (i.e., ill effects) is reported for intake of up to 10,000 IUs per day.
Health and the science of sunlight
But getting even those lower amounts isn’t easy by diet alone. A cooked 3.5-ounce serving of salmon provides 360 IUs, while 3 ounces of tuna fish in oil provide 200 IUs. Milk in any form provides 100 IUs per serving, fortified cereal 40 IUs and cooked beef only 15 IUs. Cod liver oil clocks in at a whopping 1,360 IUs.
Depending on your own skin pigmentation, the latitude of your location and cloud cover, and the amount of body fat you carry, you can get a whole lot more vitamin D just by hanging out on a beach (one hour might be the equivalent of 200 glasses of milk, 20,000 IUs). But there are big variables:
- Fair-skinned people take in the “sunshine vitamin” much more rapidly than do darker-pigmented individuals. Someone of African or South Asian heritage needs one to two hours of sun versus ten minutes for someone of Scandinavian heritage. This has significant implications for darker-skinned individuals living in northern latitudes, who have higher incidences of high blood pressure, heart disease and certain cancers, all perhaps tied to vitamin D deficiencies.
- During the winter, for obvious reasons, it’s more difficult for anyone to get as much sun exposure. Dr. Holick notes that good, regular exposure during the other three seasons helps build up vitamin D stores. While a tanning bed with UVB rays can bring a strong dose of vitamin D, the safer route still is supplementation and diet. Better yet is to get adequate amounts of sun exposure in summer and fall, which effectively enables your body to bank it for winter use. Longer winters, unfortunately, translate into D deficiency by spring.
- Obesity impairs the availability of vitamin D insofar as fat cells absorb it. It then takes a greater input of the vitamin before it is available for its beneficial effects.
So, outside the invariable matter of skin pigmentation, the directives are to eat oily fish and other foods rich in vitamin D, take supplements if you must, keep off excess body fat – and get some sun on your arms and legs. It really is a healthy glow.