What’s the danger?
Having adequate vitamin D levels is linked with better health, so for people who do not sunburn easily, some health experts recommend 10 to 15 minutes of sun exposure, three times per week, to ensure the body is making enough vitamin D. Sweden is very far north, so there is the possibility that in this population, which receives no sun exposure for much of the year, blocking sun exposure is more harmful than not blocking it; this may lower blood vitamin D to insufficient or deficient levels.
What did the new study actually find?
The Swedish researchers collected information on sun exposure and health habits from approximately 30,000 women who were 25 to 64 years old at the start of the study. Over 20 years of follow up, the women who had the least sun exposure were twice as likely to die of any cause compared with women with the most sun exposure.
On the surface, these results seem to suggest that avoiding sun exposure is bad for health, but the study authors failed to take into account important considerations. When compared with the group with “active sun exposure habits,” those women who indicated they were not exposed to sun were significantly more likely to:
be overweight or obese,
be sedentary, meaning they engaged in very little physical activity compared with the sun-exposed group, and
have a hereditary risk of melanoma.
None of these factors—all of which are important predictors of the risk of death due to any cause—were corrected or controlled for by the researchers. Further, they did not consider other diseases that may contribute to risk of death. While they assessed the use of medications for diabetes and cardiovascular disease, this approach does not provide information about other chronic diseases, such as autoimmune conditions or mobility issues that may increase risk of death.
Activities used to determine “active sun exposure”—sunbathing, winter holidays to the mountains, and vacations to warm, sunny locations—are likely related to overall health as well, as women who are frail or ill are less able to engage in these active, sun-seeking habits. It’s also possible that people who spend the most time in the sun actually are the same people who get the most sun exposure, no matter how much sunscreen they think they are applying.
Separating truth from fiction
Until a better-designed study comes along, people should continue to heed the advice of dermatologists and other experts, as the evidence still points to the importance of avoiding excess sun exposure for good health.
- Get the D. If you do not sunburn easily, for your health, aim to get 15 minutes of sun exposure three times per week. You can adjust this to account for living at northern latitudes. Even people with darker skin can develop skin cancer, so don’t overdo it.
- Screen, for sure. Make a habit of using a broad-spectrum sunscreen. It’s true the jury is still out on whether chemical-based sunscreens may have other long-term health effects, but for now the risks of not using appear to outweigh the risks of applying sunscreen. If you fear chemical sunscreens, try physical blocks. Some health experts have raised conerns about metal nano-particles in some physial formulas, but you can find zinc- or titanium-based sunscreens, that do not contain nano particles (though they may form a white sheen when applied).
- Move more. As noted, the women in the sun-exposed group were significantly more active than the sun avoiders. Regular physical activity is strongly linked to better overall health, so add movement into your day, every day. If you’re a couch potato, just 20 to 30 minutes of brisk walking will do the trick.
- Stay slim and trim. The sun avoiders were more likely to be overweight or obese. Maintain a healthy body weight throughout adulthood, and if you’re already overweight, losing just a few pounds can significantly improve health and reduce risk of death.
(Journal of Internal Medicine
, 2014, 276; 77–86)