Vitamin D3 1000 IU 250 caps.
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Vitamin D3 1000 IU 250 caps. |
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LE251 Sale Price $7.50
Vitamin D is necessary for utilization of calcium and phosphorus and in many ways acts as a hormone.1-3 The two most important forms of vitamin D are cholecalciferol (D3), which is derived from our own cholesterol and ergocalciferol (D2), a plant analogue derived from the diet. The cholecalciferol supplied by the Life Extension Buyers Club is synthetic, but its form is identical to that which is derived from cholesterol and synthesized by sunlight on the skin. Cholecalciferol Vitamin D is essential for bone growth and maintenance of bone density.4-7* Vitamin D is a fat-soluble prohormone—that is, it has no hormone activity itself, but is converted to a molecule that does, through a tightly regulated synthesis mechanism. Its two major forms are vitamin D2 (or ergocalciferol) and vitamin D3 (or cholecalciferol). Vitamin D also refers to metabolites and other analogues of these substances. Vitamin D3 is produced in skin exposed to sunlight, specifically ultraviolet B radiation. While vitamin D is best known for promoting calcium absorption and bone health, researchers have recently discovered important new roles for this versatile vitamin. As an active hormone, vitamin D is now seen as playing a central role in controlling immunity and inflammation, two vital processes that are tied to a host of age-related disease conditions. It also plays a significant role in modulating hormone levels which effect metabolism and mood. Decreased levels of vitamin D have been seen in people suffering from depression as well as obesity. Vitamin D boosts immune function and suppresses inflammation. Vitamin D down-regulates the expression of pro-inflammatory cytokines (immune cells) like tumor necrosis factor-alpha, thereby reducing inflammation which damages arteries, neurons and joints. A dietary deficiency of vitamin D inhibits the production of the protein that binds calcium in the intestines, so that calcium cannot be absorbed, even if there is adequate intake. Therefore, a deficiency in vitamin D will lead to symptoms of calcium deficiency as well. Deficiencies of vitamin D are often found in the elderly and in women who have low intake of milk and receive inadequate exposure to sunlight. Vitamin D is potent in minute quantities; one microgram of cholecalciferol has 40 IU of vitamin D activity.1,8,9 Vitamin D occurs in nature in two main forms: vitamin D2, or ergocalciferol, and vitamin D3, or cholecalciferol. While vitamin D2 is obtained from plant sources, vitamin D3 can be either obtained through animal sources, supplements, or synthesized in the skin when its precursor molecule absorbs light energy from ultraviolet B rays.83 In the liver, both vitamin D2 and vitamin D3 are converted into 25-hydroxy-vitamin D, the primary circulating form of vitamin D. Conversion into its active form, 1,25-dihydroxyvitamin D, occurs in the kidney. Pharmaceutical drug forms of activated vitamin D include calcitriol, doxercalciferol, and calcipotriene. Supplemental vitamin D is available as vitamin D2 (ergocalciferol) or vitamin D3 (cholecalciferol). Vitamin D2 is only about 20-40% as effective as D3 in maintaining serum concentrations of 25-hydroxyvitamin D, since it is more rapidly broken down in the body. For this reason, vitamin D3 (cholecalciferol) supplements are considered more beneficial than vitamin D2 (ergocalciferol) supplements. While the federal government’s recommended dietary allowance (RDA) of vitamin D is 400 IU (10 mcg) daily,10 many health experts now advise daily doses of at least 800 IU (20 mcg) of vitamin D.11 Life Extension recommends that healthy adults supplement each day with at least 1000 IU of vitamin D. Elderly adults may benefit from higher doses such as 2000 IU daily, and even up to 5000 IU daily. Research published over the last decade suggests that vitamin D toxicity is unlikely at daily intake levels of less than 10,000 IU (250 mcg).12,13-16
Dosage and Use
Caution Printed with permission of Life Extension www.lef.org. Warnings
References
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This page was last modified on Friday December 30, 2011 |
