Friday, March 18, 2011

Vitamin D3 or D2. Which is Better?

Vitamin D3 is 87 percent more potent at raising blood levels of the vitamin than vitamin D2, according results published in Journal of Clinical Endocrinology & Metabolism. Vitamin D3 also produced a 2- to 3-fold increase in the storage of the vitamin, compared with vitamin D2.

Subjects were supplemented with 50,000 International Units (IU) of either vitamin D2 or D3 per week for 12 weeks. Results showed that about 17 percent of the D3 ingested was stored by the subjects, and the rest was consumed or metabolized or both.
By the various measures employed, D3 was from 56 to 87 percent more potent than D2 in raising serum 25(OH)D, and more than three times as potent in increasing fat calciferol content.

Vitamin D refers to two biologically inactive precursors - D3, also known as cholecalciferol, and D2, also known as ergocalciferol. Both D3 and D2 precursors are transformed in the liver and kidneys into 25- hydroxyvitamin D (25(OH)D), the non-active 'storage' form, and 1,25-dihydroxyvitamin D (1,25(OH)2D), the biologically active form that is tightly controlled by the body.

Vitamin D2 can be obtained by prescription only while D3 is widely available OTC.

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