Vitamin D, often referred to as "the sunshine vitamin," can play a major role in your health and the way you feel. Your body synthesizes a large amount of the nutrient after exposure to the sun's rays so, to avoid deficiency, you may want to consider supplements during winter months. Manufacturers offer such products in two forms: vitamin D2 and D3.
Genetic Benefit
Far from simply protecting you from rickets, Dr. Joseph Mercola explains how the nutrient can impact on your metabolism in a number of ways. The physician, an author of several books on natural approaches to health, explains that your body produces 30,000 genes, and vitamin D controls 2,000 of them. He links vitamin D deficiency with increased risk of cancer, heart disease and autoimmune conditions.
More Benefits
The National Institutes of Health note how the body converts vitamin D into a storage form, known as 25-hydroxy-cholecalciferol or calcidiol. When required, this converts into 1,25-hydroxy-cholecalciferol or calcitriol, the active form of vitamin D throughout the body. This form increases insulin sensitivity, boosts the function of the immune system and regulates cell proliferation.
Vitamin D2
The only natural source of vitamin D2, or ergocalciferol, comes from certain mushrooms exposed to sunlight during their growth. However, almost all of the vitamin D2 available results from manufacturers forming the compound using ultraviolet irradiation of ergosterol compounds found in yeast. Although vitamin D2 traditionally has been used to fortify milk products as a preventive step against rickets, the National Institutes of Health, or NIH, points out that this form does not convert into calcidiol and calcitriol at the same rate as vitamin D3; most supplement manufacturers no longer use D2 in their products for this reason.
Vitamin D3
Dr. Andrew Weil, the physician well known for his integration of both mainstream and nutritional approaches, considers vitamin D3 a superior form. The compound, also known as cholecalciferol, exists naturally in fish oils and offal, and also represents the form manufactured in the skin after sunlight exposure. D3 boosts circulating levels of calcidiol several times more effectively than its D2 counterpart, and the elevations are sustained for a longer period.
Dosage
Researchers do not yet agree on a definitive dose for vitamin D supplementation. Weil conservatively suggests a daily intake of 2,000 international units, or IU, of vitamin D3, although he points out that no adverse affects occur with intakes of up to 10,000 units per day.
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