Julie was heading for an all-inclusive week in Cancun to loll on a vast expanse of beach, soaking up rays and having someone named Juan bring her endless piña coladas (she planned to get her money’s worth). Sounded pretty nice to me. After months of Chicago overcast/gray, it seemed like a perfect way to put seasonal affective disorder to bed for the winter.
Julie was reasonably concerned about her time on the beach. What about sunblock? Which one? How long could she be out there?
For we who are left behind, it’s April, and while not yet balmy, Chicago does have a lakefront with lots of beaches and parks and plenty of sunshine to come. If we work near windows, we might also be getting a lot more sunlight than we think. So this Health Tip applies to us all.
A new approach to the sun
I related some compelling news to Julie. Based on a Swedish study published last month, there’s a whole new way she (and we) can approach the sun.
Study researchers followed 30,000 women 25 to 64 over a period of 20 years, collecting information about personal sun exposure, activities like sunbathing (winter and summer), and asking whether they consciously chose “sun vacations” and if they used tanning beds. Except for tanning-bed users, just about everyone used sunblock, helpful to prevent sunburn and premature skin aging, but as we’ll soon see completely ineffective for skin cancer prevention.
Based on their own reporting, the 30,000 women were divided into five groups, ranging from Group 0 (deliberate avoidance of sun) to Group 4 (greatest sun exposure).
After 20 years, to everyone’s surprise, Group 4 was statistically the healthiest. They had developed the fewest chronic illnesses, especially heart disease, and had the lowest death rate. In Group 4, there was also a slightly higher rate of cancers of all types, but this was attributed to the fact that they were living longer than those in the other groups rather than to sun exposure itself.
As sun exposure declined, health stats worsened
Group 0 (with the least sun exposure) had the highest amount of chronic illness and a death rate virtually equal to that of cigarette smokers. The authors’ startling conclusion: when it comes to serious health risks, sun avoidance joins obesity, smoking, and a sedentary life as a harbinger of ill health.
“But,” you’re tempted to splutter, “What about skin cancer? Aren’t these Group-4 bronzed goddesses dying of skin cancer?”
It turned out that the five groups of women developed skin cancer about equally, but among those who got the potentially fatal skin cancer melanoma, those with the most sun exposure were the least likely to die from the disease. That curious fact is attributed to the higher vitamin D levels in Group 4. Melanoma patients with high levels of D have a lower rate of the cancer spreading throughout the body.
A primer on sun
So whether it’s Julie heading to Cancun or you to Oak Street Beach (or just your own backyard), here’s some sunny info:
- You get two forms of ultraviolet light from the sun, UV-A and UV-B. It’s the UV-B that causes both suntan and sunburn. UV-A is linked to skin cancers, including melanoma. Sunblocks (see below) block UV-B but not UV-A. However, tanning itself (UV-B) can to a certain extent protect you from UV-A cancer. Amazingly enough, blocking your tan with excessive sunblock can slightly increase melanoma risk.
- UV-B is also responsible for your body’s production of vitamin D. The combination of low sun exposure and sunblock use can result in low levels of D. This can increase your risk for a variety of chronic illnesses, including cancer. However, you can also maintain normal D levels by taking a vitamin D supplement.
- Glass windows block both the tanning and D effects of UV-B but not the cancer risks of UV-A. If you work in a sunny office, you actually have a higher melanoma risk than someone who works outdoors.
- The sun exposure that’s quite dangerous is having repeated intense burns, especially during childhood. This is because high UV-A exposure occurs before UV-B has time to create a protective tan and higher vitamin D levels.
- You’d be right if you’re thinking that given tanning’s protective effect, people with darker skin have lower rates of skin cancer. However, pigmentation reduces vitamin D production in the skin and thus those with darker skin should take 2,000 IU of supplemental vitamin D daily.
- Advice for Julie. Since Julie’s been indoors all winter and her vitamin D is likely on the low side, she should ramp up her D levels before hitting the beach. Having a healthy amount of D will protect her from skin cancer. She should take 5,000 IU daily starting about a month before departure, maintaining her levels at about 2,000 IU daily after her return.
- Julie will need to use sunblock to prevent sunburn and reduce the aging effects of sun exposure. The SPF on the bottle stands for sun protection factor. SPF 15 blocks 93% of UV-B, which is just fine unless she’s sun-sensitive and burns easily (SPF 30 blocks 97% of UV-B, SPF 50 blocks 98%). Julie can expect about five hours of protection with each application of sunblock, though it will wash away the moment she goes for a swim. She should use about a shot glass full of lotion (plenty of shot glasses at her all-inclusive) with every application. But remember, a little bit of tan is actually protective, so she can start the first 15 minutes of her day with no sunblock, or until her skin reddens slightly.
- Tanning beds and other types of indoor tanning have definite sunburn and skin cancer risks, especially for anyone under 21 because you’re getting both UV-A and UV-B exposure over your entire body without any sunblock.
The take-aways for today: sun exposure is good for you. With it you’ll live a longer and healthier life. Protect your skin from burning and premature aging with sunblock. Avoid tanning beds (despite the hype, there are no “safe” tanning beds).
Wishing I were the one now ordering another piña colada from Juan…
David Edelberg, MD