If it bears out, it will challenge one of medicine's most fundamental beliefs: that people need to coat themselves with sunscreen whenever they're in the sun. Doing that may actually contribute to far more cancer deaths than it prevents, some researchers think.

Vitamin D has achieved “super vitamin” status recently with theories that it holds the power to prevent everything from lung cancer to osteoporosis. Some researchers now believe that getting sufficient amounts of vitamin D—which is difficult to do through food alone—is best done naturally through sun absorption and not supplements.

Scientists are excited about a vitamin again. But unlike fads that sizzled and fizzled, the evidence this time is strong and keeps growing. If it bears out, it will challenge one of medicine's most fundamental beliefs: that people need to coat themselves with sunscreen whenever they're in the sun.

According to popular natural health expert Dr. Joseph Mercola, most people suffer from "sunlight starvation". To make up for our natural light deficiency, he recommends the use of full spectrum lighting - the next best thing to sunshine.

The vitamin is D, nicknamed the "sunshine vitamin" because the skin makes it from ultraviolet rays. Sunscreen blocks its production, but dermatologists and health agencies have long preached that such lotions are needed to prevent skin cancer.