After fearing the sun for decades, listening to the dire warnings of dermatologists and slathering on sunscreen to protect against skin cancer, it turns out we are getting too little sun. Apparently the majority of American women are deficient in vitamin D-3 – the form that is derived from sunlight’s interaction with bare skin.

Two recent studies suggest that women who get lots of vitamin D are less likely to develop breast cancer. This adds to the already strong, mounting evidence that the “sunshine vitamin” helps prevent many types of cancer, as well as improves survival rates among those already afflicted. What’s more, vitamin D may also lower the risk of developing Type 2 diabetes.

In one study, high levels of vitamin D translated to a 50 percent lower risk of breast cancer. Even modestly higher levels resulted in 10 percent less risk. A second study, this one by Canadian researchers, found that women who spent time outdoors, especially in their teen years, were 25 to 45 percent less likely to develop breast cancer than women with less of the vitamin. Only 24 percent of women in the Canadian study had sufficient blood levels of D at the time that their breast cancer was diagnosed. Those who were deficient were nearly twice as likely to have their cancer recur or spread over the next 10 years, and 73 percent more likely to die of the disease.

Most researchers agree that vitamin D from supplements or food is less effective at fighting disease than the kind produced in the skin as a result of the sun’s ultraviolet rays. About 15 minutes of sunlight directly on skin several times per week is all it takes to give us the amount we need.

Is it possible that the majority of American women don’t actually absorb 15 minutes worth of sunlight a day? Think of your routine. It’s easy to shun sunlight, particularly in the dead of winter or the worst heat of summer, especially when we’ve been repeatedly instructed to stay out of the sun. Many aspects of our lifestyle – among them, automobiles, garages and indoor exercise equipment – help “protect” us from the rays.

But swallowing large amounts of vitamin D supplements would also be a serious mistake. High doses of it can cause nausea, vomiting and raise blood levels of calcium enough to cause mental confusion and heart rhythm abnormalities. Too much vitamin D can also lead to calcium deposits in the kidneys and other tissue.

We’ve been through this all before: Something is bad for us, and then it turns out, it’s good for us – in moderation, that is. A little coffee improves circulation and heart health. Too much coffee disrupts your sleep and turns you into a hyperactive maniac. In moderate amounts, red wine guards against heart attacks, strokes and perhaps Alzheimer’s. Too much wine rots your liver. A little dark chocolate lowers your blood pressure. Too much packs on the pounds.

Now we’ve got one more to add to the list. Too much sunshine gives you skin cancer. Too little and you’re flirting with breast cancer. (Men, you also need vitamin D. Its link to the prevention of prostate cancer is likely and is being studied.)

The seeming contradictions in medical research do not concern me. When it all shakes out, my theory on life is always confirmed: “moderation in all things.”

Yet I cannot hide my excitement about four developments. One, the heart-healthy benefits of red wine – now I can feel good about my daily glass with dinner each evening. Two, “sunshine on my shoulders makes me happy,” to quote a John Denver song. Three, dark chocolate – it’s role in happiness can never be exaggerated. And four, I always down two mugs of coffee in the morning and now don’t have to feel guilty about that either.

Actually, I had already given up on the guilt thing. I’m for moderation in all things, even in that department. I have decided, for the most part, what passes for “guilt” is a useless, self-defeating reaction. So when I feel that free-floating discomfort I recognize as “guilt,” I ask myself why. If it’s because I hurt someone, then my inner voice is telling me to go set it right. If the feeling arises over trivial things like eating a hot dog or lingering at the lake instead of working, I say, “Get thee behind me, Guilt.”

At any rate, stop feeling guilty about the sun. Go out and get your 15 minutes today. It could save your life.