Today on BodyTalk Dr. Greg Plotnikoff will answer your questions about vitamin D — how to get enough and what happens when you don’t.

Plotnikoff,  medical director of the Institute for Health and Healing at Abbott Northwestern Hospital, may know a lot about health care, but he’s obsessed with vitamin D.  It’s far more than your run of the mill nutrient. It regulates hundreds of genes, and not getting enough of it has been linked to more than dozen different kinds of cancers and many other diseases.

Those of us who live up here on the tundra are especially vulnerable, because it’s just not possible to get enough vitamin D from the sun in the winter. Even in summer, slathering sun screen on you and your loved ones blocks UVB rays — and vitamin D.

But how much is enough? How do you balance too much sun with not enough? What’s a redhead to do? We all need supplements, especially in winter, but how many pills should you take? And infants?

Ask Dr. Vitamin. You can post question anytime, and he’ll share his wisdom here this afternoon starting around 1 p.m.

If you want to stay healthy go out into the sun. Or take vitamin D pills. Not only does vitamin D help prevent cancer, heart disease, and diabetes, it may also help to prevent death from all causes, according to a study published Monday in the Archives of Internal Medicine.

Researchers at the Albert Einstein College of Medicine in New York analyzed vitamin D levels in 13,331 people. More than half of the women and 43 percent of the men were vitamin D deficient, meaning that they had less than 30 nanogram per milliliter of blood. Nearly nine years later 1,806 of the study subjects had died. Those who had the lowest levels of vitamin D in their blood — less than 17.8 nanograms per millileter– had a 26 percent higher rate of death from any cause compared to those with the highest levels of vitamin D.

It doesn’t prove that low levels of vitamin D caused their illnesses or their deaths. But its the latest of many studies that are raising questions about whether our chronic health problems could be improved with higher doses of vitamin D. The standard recommendations is 400 units per day, but experts now are thinking that might be too low.

It may be harder than you think to get enough from the sun, which is the major source. The further north you live, the darker your skin, how much sun screen you use, and the older you are all affect how much your body can make. Less than 10 percent, on average, comes from food.

Many health experts now recommend that you ask your doctor to test your vitamin D level, and, if it’s below normal, to prescribe supplements.

And go outside, because at least for now, the sun is shining.