Vitamin D includes five fat-soluble compounds necessary for strong bones and an active immune system. Vitamin D-2, obtained from food, and vitamin D-3, produced by the skin in response to sunlight, are the most important types for human biochemistry. According to a 2009 article in “Scientific American,” vitamin D deficiency claims up to 75 percent of U.S. teens and adults. Vitamin D deficiency can be naturally remedied by increased sun exposure, a modified diet and supplementation.
Vitamin D From Sunlight
The best natural remedy for vitamin D deficiency is sun exposure. The skin produces vitamin D-3 when UV-B radiation from the sun stimulates a cholesterol-based compound called 7-dehydrocholesterol. The sun’s UV index must be greater than three for this chemical reaction to occur within the skin. Some regions of the world do not receive consistently high levels of UV-B radiation, which is a major contributing factor in vitamin D deficiency. Symptoms of deficiency begin with reduced immune function and can progress to bone malformations such as rickets, a childhood disease characterized by “soft bones” leading to bowed legs.
Dietary Sources of Vitamin D
Vitamin D is not incorporated into many foods naturally, which is why it is often added to dietary staples such as milk, yogurt, margarine, orange juice and breakfast cereals. The National Institutes of Health states that fish is often the best source of vitamin D . As a rule, fish caught in the wild have more vitamin D content than farmed fish. Fish oils, such as cod liver oil, are actually the richest sources of vitamin D per gram. Other good sources of vitamin D include beef liver, shrimp, egg yolks and some cheeses.