In the absence of Vitamin D from sunlight, disease increases more than 1000 percent . Experts suggest that the chances of getting vitamin D from your diet are very low. And if you are a vegetarian, it is all the more difficult to gain vitamin D. What they repeatedly suggest is exposure to sunlight is the best source of vitamin D. Humans spend less time in the sun today than at any point in human history — which is why more than 1 billion people worldwide are vitamin D deficient.
Humans make 90 percent of our vitamin D naturally from sunlight exposure to our skin — specifically, from ultraviolet B exposure to the skin, which naturally initiates the conversion of cholesterol in the skin to vitamin D3.
Researchers have also discovered specific molecular signaling events by which vitamin D prevents inflammation. In their experiments, they showed that low levels of Vitamin D, comparable to levels found in millions of people, failed to inhibit the inflammatory cascade–a series of rapid biochemical events which propagates and matures the inflammatory response. However, levels considered adequate did inhibit inflammatory signaling .