There are two sets of reasons why sunscreens may be doing you more harm than good.
One set of reasons has to do with the toxic chemicals in the sunscreen that are absorbed through your skin and can do damage.
“Chemical” sunscreens frequently contain oxybenzone or related chemicals. These are hormone disruptors. That can’t be good for you.
“Mineral” sunscreens (containing zinc oxide or titanium dioxide) are probably safer.
But even if you switch to a mineral-type sunscreen, there’s a second possible danger.
That’s because you get a major health boost from the sun and using sunscreen limits that benefit.
Sun exposure is best-known for triggering your body’s vitamin D synthesis. But the sun stimulates other aspects of your metabolism, too. For instance, sunlight also signals your skin to produce nitric oxide – a chemical that dilates your blood vessels and lowers your blood pressure.
In fact, some scientists believe that many of the health benefits attributed to vitamin D are actually the result of this increase in nitric oxide, as well as serotonin, endorphins, and other hormones stimulated by sun exposure.
People who enjoy exposure to sunlight not only have lower blood pressure but have substantially lower overall mortality than those who avoid the sun. In fact, the longevity gap in one Swedish study between sun avoiders and sun worshippers was comparable to the gap between smokers and non-smokers.
What about skin cancer?
Here’s the paradox. Those who spend lots of time in the sun do have a higher incidence of skin cancer. But they actually have a lower risk of dying from skin cancer.
The two most common skin cancers — basal cell carcinoma and squamous cell carcinoma — do occur at higher rates among sun bathers. But these two types of cancer are reasonably benign and easily treated.
It’s only the third type of skin cancer — melanoma — that poses the real danger. Those who spend a lot of time in the sun — outdoor workers, for instance — actually have a lower incidence of melanoma.
The sun is still to blame when it comes to melanoma, however. But the risk for melanoma rises from intermittent sun exposure leading to a sunburn, especially when you’re young.
In the end, it may turn out that the healthy brown tan I remember as being the standard of attractiveness back in the sixties and seventies is, in fact, healthy and protective.