Most people get the vitamin D that they need from sun exposure. Vitamin D is a fat-soluble vitamin that the body needs to aid in the absorption of calcium and phosphorous and is necessary for normal thyroid function, immune function, blood clotting and the regulation of more than two thousand genes that affect the proliferation and death of cells. It is essential for the formation, growth and repair of bones.
Deficiency in vitamin D may lead to muscle weakness, irregular heartbeat, depression, heart disease, birth defects, stroke, hypertension, dementia, impaired bone mineralization, fibromyalgia, insomnia, eye problems, multiple sclerosis, chronic diseases, and cancers including skin, breast and prostate cancer.
There are different forms of vitamin D, the most natural and active of which is D3. This is obtained through exposure of the skin to ultraviolet rays emitted in sunlight, and there is a cholesterol compound in the skin is a precursor of vitamin D. This vitamin can also be obtained from certain healthy recipes in the form of D2 or D3, and from dietary supplements in the form of D5. The vitamin D obtained from food and supplements is activated only when it us processed in the liver and kidneys where it s converted and circulated through the blood.
While sun exposure is the best source of vitamin D and diet is not a sufficient source for this vitamin, some foods that may increase the amount of vitamin D in the body include fatty saltwater fish and fish liver oils from such fish like sardines, salmon, halibut, and cod liver oil. Other healthy meals that contain amounts of vitamin D include oatmeal, cereals, dandelion greens, and sweet potatoes. Some foods such as eggs and dairy are fortified with vitamin D. Those who do not have sufficient exposure to sunlight may opt for supplementation in the form of vitamin D capsules.
Some studies have shown that higher intake of vitamin D from food and supplements and higher levels of vitamin D in the blood are associated with reduced risk of colorectal cancer. A study involving 1,179 healthy women from Nebraska showed that the group receiving vitamin D and calcium supplements had 60 percent decrease in cancer risk compared to a placebo group.