The Gilchrest view of vitamin D and sun exposure

Dr. Barbara Gilchrest is professor and head of the Department of Dermatology at Boston University School of Medicine.

Here’s a summary of her take on vitamin D deficiency and the risks and benefits of exposure to the sun.

The pseudo-controversy

• The media report a “medical controversy” that pits the unwanted effects of acute sunburn, photoaging, and skin cancer against the benefits of vitamin D photosynthesis.
• It’s virtually impossible to find a definition of the recently coined term “vitamin D deficiency” in the medical literature.
• And, the media ignore the fact that people get ample vitamin D levels from a combination of diet, supplements, and incidental protected sun exposure.

The reality

• The great majority of people with insufficient 25(OH)D (vitamin D) levels have no detectable disease or health problem, and probably never will.
• There’s no benefit from a high 25(OH)D blood levels, and no harm from a lower level.

Does increasing a person’s “normal” blood 25(OH)D level have health benefits?

• The results of available studies are conflicting.
• Today, we just don’t know.

The bottom line?
According to Dr. Gilchrest, common sense and medical research support the fact that fair-skinned people benefit from regular, lifelong, safe sun practices.

Some claim that sunscreens block all UV (and hence, all vitamin D photosynthesis). But sunscreens allow continuous transmission of a fraction of UV photons equal to 1/SPF; and sunscreen users customarily apply half or less of the FDA-stipulated amount of product required to generate the stated level of protection.

In addition, people who wear high-sun protection factor (SPF) sunscreen probably synthesize vitamin D maximally in exposed areas during incidental sun exposure.

Most important, regardless of one’s complexion or the extent of UV exposure, daily vitamin D supplementation taken by mouth can compensate for the lack of vitamin D production in the skin.

Use injections if you’re one of the rare people who can’t take vitamin D by mouth. Routine measurement of the blood 25(OH)D levels isn’t warranted. The test is expensive and the “normal” or “optimal” range is debatable.

8/1/08 17:49 JR