The Sunscreen Dilemma

Experts have encouraged sunscreen use as protection against the skin damage that leads to malignant melanoma. Unfortunately, these sunscreens prevent the skin from making vitamin D from sunlight – and many studies now suggest that vitamin D is protective against cancer. Sunscreen is designed to block UV penetration into the skin. That’s precisely why it prevents sunburn. This is also why it prevents production of vitamin D. Even relatively weak sunscreens (as low as SPF-8) will block UV and stop vitamin D production.

But does sunscreen help prevent skin cancer? A 1999 meta-analysis of 13 epidemiological studies on the relation of sunscreen use to melanoma risk found that three studies showed a decreased risk of melanoma, but four showed an increased risk and six were inconclusive. Why would it increase risk? The explanation is simple. Most chemical sunscreens block ultraviolet B (UVB), but are transparent to ultraviolet A (UVA). More than 90 percent of the ultraviolet light from the sun is UVA.

Sunscreens work very well to prevent your skin from getting red or sunburned. They allow us to stay out in the sun much longer than we would if we were getting burnt. As a result, the skin ends up more damaged than if we hadn’t used sunscreen.

So, wearing sunscreen prevents sunburns, but research suggests it might not reduce your risk of developing cancer; in fact, it might actually increase your risk. That’s the sunscreen dilemma. Is there an easy solution? Not necessarily. Applying sunscreen will prevent vitamin D production and result in more skin damage, since it enables you to increase your sun exposure without burning. On the other hand, staying out in the sun for hours without sunscreen certainly won’t help you avoid skin cancer, either.

Perhaps the morale to this story is that sun exposure for as little as 10 minutes a day will stimulate ample vitamin D production, but is not likely (unless perhaps you are extremely fair skinned) to cause any sunburn or skin damage – and that’s the best way to reduce your risk while still enjoying the health benefits of vitamin D. Talk to your doctor for more information.

In Health,

Dr Andy