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Raising Vitamin D vs. Reducing Skin Cancer:

Are They Mutually Exclusive Goals?

from: Holistic Primary Care, Spring 2009 (
By Michael Traub, ND

It is a strange paradox of nature that the same wavelengths of solar UV light that drive cutaneous vitamin D photosynthesis are the very same ones that cause DNA damage and skin cancer. That conjunction of healthful and harmful effects has caused a good bit of consternation in medical circles in recent years.

As we’ve learned more about the importance of vitamin D, the extent of vitamin D insufficiency, and the negative effects of low D levels, some physicians now oppose skin cancer prevention efforts focused on avoiding sun exposure and diligent sunscreen use. They argue that on a population basis, gains in reducing skin cancers are outweighed by increased risk of colorectal cancer, diabetes, heart disease, depression, MS and osteoporosis associated with low vitamin D.

Since vitamin D is easily obtained from oral supplements, why has sun protection become so controversial? Is there real cause for concern or is this a “pseudocontroversy?” I think it is the latter.

Be aware that arguments against UV protection are heavily promoted by the $5 billion/year indoor tanning industry that encourages tanning bed use as a way to obtain vitamin D and its health benefits. Such a claim is illegal and is currently being litigated, but it is still prevalent. Indoor tanning does not focus on the frail elderly or inner-city ethnic minorities who are at greatest risk of vitamin D deficiency, but rather on healthy Caucasian teens and young adults, who are at highest risk of UV photodamage and subsequent skin cancer later in life.

A Pseudo-Controversy

The basis of the pseudo-controversy over sun exposure and skin protection is the assumption that vitamin D sufficiency is best achieved from UV exposure, even though all intervention studies showing benefit from increasing 25(OH)D were done with oral vitamin D, not increased sun/UV exposure (Wolpowitz D, Gilchrest BA. J Am Acad Dermatol 54(2):301-17 (2006 Feb).

Unfortunately, evolution has not kept up with civilization. Life expectancy was less than 40 years when we humans evolved the capacity for cutaneous vitamin D production; long-term photodamage was not a concern, and vitamin D deficiency, in the form of rickets, was fatal in early life.

The debate over sun-avoidance fails to acknowledge that most peoples’ motivation for sun exposure is not improved general health, but to attain the cosmetic goal of tanning. The “debate” between medical professional groups with primary interests in dermatology versus those who specialize in endocrinology really does not exist.

To be sure, the notion of relaxing in the sun and making one’s own vitamin D has a back-to-nature holistic appeal. But the fact is, most people can obtain ample vitamin D levels from a combination of diet, supplements, and incidental protected sun exposure. (For more on this, join, and read “Vitamin D: New Findings, New Questions,” Vol. 9, No. 2. Summer, 2008).

What Should We Tell Our Patients?

The preponderance of medical literature and common sense indicate that light-skinned people benefit from regular, lifelong, safe sun practices. People who apply high-sun protection factor (SPF) sunscreen probably synthesize vitamin D maximally in exposed areas during incidental sun exposure (Gilchrest BA. J Natl Cancer Inst 2008: in press.)

Although some claim that sunscreens block all UV and all vitamin D photosynthesis, this is not the case. Sunscreens allow continuous transmission of a fraction of incident UV photons equal to 1/SPF. In other words, an SPF 15 product still allows 1/15th or 7% of UV photons into the skin.

Sunscreen users typically apply half or less of the FDA-stipulated amount of product needed to obtain the advertised protection level (Bech-Thomsen N, Wulf HC. Photodermatol Photoimmunol Photomed. 1992: 9(6):242-4). Observation of people engaged in activities at parks and gardens, golf courses, tennis courts, pools and beaches showed a high degree of unprotected UV exposure, especially on golf courses (Dixon HG et al. Cancer Epidemiol Biomarkers Prev. 2008 Feb;17(2):428-34).

If people require 2-8 minutes of unprotected summer sun exposure to maximize vitamin D synthesis, they could attain this in approximately 10-20 minutes after applying SPF 15-30 sunscreens. But let’s not forget that oral vitamin D can completely compensate for any lack of cutaneous vitamin D photosynthesis.

I am often asked to recommend a “safe” sunscreen. A recent report renewed concerns about sunscreen safety. The Centers for Disease Control published a national survey of 2,500 Americans, age 6 and up, showing that the UV filter oxybenzone readily absorbs into the skin and is present in 97% of Americans tested (Calafat AM, et al. 2008. Environ Health Perspect. 2008;116).

The problem is, oxybenzone, AKA, benzophenone-3, has been linked to allergies, hormone disruption, and cell damage (Schlumpf M, et al. Toxicology. 2004: 205(1-2): 113-122. Typically, women and girls had higher levels than men and boys, probably due to greater use of body care products and sunscreens.

Oxybenzone is none-too-healthy for the environment. It can trigger outbreaks of viral infection in coral reefs; up to 10% of coral reefs are threatened by sunscreen-induced bleaching (Danovaro R, et al. Environ Health Perspect 2008: 116(4): 441-447).

We can all minimize our negative impact on our inner and outer ecology by using sunscreens with physical filters, which reflect instead of absorb ultraviolet radiation; and choosing eco-friendly chemical sunscreens. One such product is Soleo, an organic, water-resistant, biodegradable formulation of 22.3% zinc oxide and other natural ingredients. Other paraben-free physical sun blockers (zinc and/or titanium) we recommend are: SolRx, MyChelle Sun Shield SPF 28 and DDF Organic Sun Protection SPF 30.

Lastly, don’t forget UV-protective clothing, hats, sunglasses, and lip protection!