Vitamin D: Let the Sun Shine In (in moderation)

Have you been going around incognito this summer, buried beneath a wide brimmed hat, sunglasses and light but long sleeved clothing? Do you drive behind tinted windows and only show your face after dark? We all seem to be panicked by the sun, and for good reason: Skin cancer is on the rise, with 7,900 deaths each year due to melanomas. The mortality rate is increasing 50 percent since the 1970s, according to the American Cancer Society. Adding to the dismal statistics, the sun is stronger and our ozone layer thinner.

As we slather on the sunscreen, it is important to remember the sun’s role in our health. Human beings are dependent upon some exposure to sunlight. And while the rate of sun- related skin conditions has risen, new research says that the health risks of completely avoiding the sun may be riskier than the consequences of adding a little more sunshine to our day.

Our bodies have a strong dependence on sunshine because up to 90 percent of the body’s supply of vitamin D is made in the skin with the help of the sun’s UV-B rays. The sun, with the help of cholesterol, triggers vitamin D synthesis. It is then converted in the liver and kidneys to its active form, ‘‘1,25 dihydroxyvitamin D.” Just exposing your arms and legs to the sun for 15 minutes each day — recommended by the Office of Dietary Supplements at the National Institutes of Health — supplies up to 20,000 I.U.s of vitamin D, far more than the current recommended daily allowance (RDA) of 400 I.U.s. You can also get vitamin D through foods, with highest concentrations found in fish (your grandmother knew best when she spoke of a tablespoon of cod liver oil a day), fortified milk (ice creams and cheese don’t count) and egg yolks. We need more as we age because we lose some ability to convert vitamin D into its active form. But, age aside, most Americans are deficient in vitamin D, with surveys indicating that 50 percent of young and elderly woman do not consume the base, acceptable amount. The National Health and Nutrition Examination Survey also reports that deficiencies are more common among African American women (42 percent) than Hispanic and white women.

Why all the fuss about just one vitamin? Although vitamin D is most commonly associated with better calcium absorption and bone health, it is also critically important for muscle strength, insulin activity, immune health, autoimmune disease and resistance to cancers like prostate, breast and colon cancer. Dr. Walter Willet of the Harvard School of Public Health believes that 30 percent of human cancers may be related to a vitamin D deficiency.

Check out www.vitamindcouncil.com and you will find studies, articles and conferences that warn of the many risks of a vitamin D deficiency.

While the scientific community agrees that Americans are at risk for low levels of D, there has also been a groundswell of discussion and debate regarding the appropriate amounts necessary. More nutritionists and doctors are recommending higher amounts for optimal health and disease prevention. Most notable are the recent conferences about the potential decrease in cancer mortality when vitamin D levels are increased. In another report, the Nurses Health Study evaluated the risk of a deficiency and concluded that a combined intake of 1200 mg of calcium plus 800 I.U.s of vitamin D was associated with a 33 percent lower risk of Type 2 Diabetes. New limits range from 800 I.U.s/day to 2,000 I.U.s/day. Because exceeding a prescribed limit of D can cause toxicities, communicating the correct dose to the public is critical.

But most agree that we are just not getting enough of vitamin D. Factors such as geographic location, skin pigmentation and steroid use all play a role in depleting us of optimal levels. Lifestyle choices like extended day care for children also reduce exposure. Even breastfeeding, which is gaining in popularity, can deprive infants of much-needed vitamin D, because breast milk does not contain adequate amounts. One hundred years ago infants were exclusively breast fed, but they also received sun exposure. However, the American Academy of Pediatrics now recommends sunscreen at 6 months, covering up infants in protective clothing, and limiting sun exposure in general. Thankfully, the AAP also recommends a vitamin D supplement for any mother who is breastfeeding without additional supplementation.

But let’s give the sun a break, for a moment, and mention some other ways that your risk of skin cancer can increase. Smoking can triple your risk of skin cancer. The toxic smoke contains chemicals that suppress immune function which is needed to heal sun damage. Antibiotics, oral contraceptives, anti-depressants and alcohol can also raise skin cancer risk, by over sensitizing skin to UV rays.

Risk factorsfor vitamin D deficiency

Limited sun exposure: Limits ability of the skin to make adequate amounts of D.

Dark skin: Darker skin inhibits absorption of D from the sun.

Fat malabsorption conditions: Conditions such as celiac, liver disease, & Crohns can inhibit fat absorbtion. Vitamin D needs fat in diet in order to be absorbed.

Steroid use: May impair vitamin D metabolism.

High caffeine use: More research is needed, but some suggest that caffeine decreases absorption and bone mineral density

Poor diet: Individuals who avoid eating oily fish, liver, egg yolks and do not take a multivitamin. Many foods are fortified with D but not at the levels that would ensure adequate absorption.

Age: Individuals who are 55+. Older adults do not absorb vitamin D as well, may be home bound more, and require higher levels.

So don’t just blame the sun for skin cancer. And remember the importance of vitamin D this month. Try putting on the sunscreen after you offer up your arms and legs for 15 minutes a day. It’s the easiest way to ensure that you are getting your daily dose of a very important nutrient. Best of all, it’s free.

E-mail questions or comments to Susan Mudd.