Vitamin D(3) is more potent than vitamin D(2) in humans.

BACKGROUND Current unitage for the calciferols suggests that equimolar quantities of vitamins D(2) (D2) and D(3) (D3) are biologically equivalent. Published studies yield mixed results. OBJECTIVE The aim of the study was to compare the potencies of D2 and D3. DESIGN The trial used a single-blind, randomized design in 33 healthy adults. Calciferols were dosed at 50,000 IU/wk for 12 wk. Principal outcome variables were area under the curve for incremental total 25-hydroxyvitamin D [25(OH)D] and change in calciferol content of sc fat. RESULTS Incremental mean (sd) 25(OH)D area under the curve at 12 wk was 1366 ng · d/ml (516) for the D2-treated group and 2136 (606) for the D3 (P < 0.001). Mean (sd) steady-state 25(OH)D increments showed similar differences: 24 ng/ml for D2 (10.3) and 45 ng/ml (16.2) for D3 (P <0.001). Subcutaneous fat content of D2 rose by 50 μg/kg in the D2-treated group, and D3 content rose by 104 μg/kg in the D3-treated group. Total calciferol in fat rose by only 33 ng/kg in the D2-treated, whereas it rose by 104 μg/kg in the D3-treated group. Extrapolating to total body fat D3, storage amounted to just 17% of the administered dose. CONCLUSION D3 is approximately 87% more potent in raising and maintaining serum 25(OH)D concentrations and produces 2- to 3-fold greater storage of vitamin D than does equimolar D2. For neither was there evidence of sequestration in fat, as had been postulated for doses in this range. Given its greater potency and lower cost, D3 should be the preferred treatment option when correcting vitamin D deficiency.

[1]  M. Holick,et al.  Development and validation of control materials for the measurement of vitamin D3 in selected US foods , 2008 .

[2]  P. Glendenning,et al.  Serum 25-hydroxyvitamin D levels in vitamin D-insufficient hip fracture patients after supplementation with ergocalciferol and cholecalciferol. , 2009, Bone.

[3]  A. Zonderman,et al.  Associations among 25-hydroxyvitamin D, diet quality, and metabolic disturbance differ by adiposity in adults in the United States. , 2010, The Journal of clinical endocrinology and metabolism.

[4]  B. Hollis,et al.  Vitamin D2 is much less effective than vitamin D3 in humans. , 2004, The Journal of clinical endocrinology and metabolism.

[5]  S. Booth,et al.  Vitamin D3 in fat tissue , 2008, Endocrine.

[6]  P. Deurenberg,et al.  Body mass index as a measure of body fatness: age- and sex-specific prediction formulas , 1991, British Journal of Nutrition.

[7]  R. Horst,et al.  Discrimination in the metabolism of orally dosed ergocalciferol and cholecalciferol by the pig, rat and chick. , 1982, The Biochemical journal.

[8]  R. Heaney,et al.  Pharmacokinetics of a single, large dose of cholecalciferol. , 2008, The American journal of clinical nutrition.

[9]  R. Vasan,et al.  Adiposity, Cardiometabolic Risk, and Vitamin D Status: The Framingham Heart Study , 2009, Diabetes.

[10]  R. Vieth,et al.  Evidence that vitamin D3 increases serum 25-hydroxyvitamin D more efficiently than does vitamin D2. , 1998, The American journal of clinical nutrition.

[11]  M. Holick,et al.  Vitamin D2 is as effective as vitamin D3 in maintaining circulating concentrations of 25-hydroxyvitamin D. , 2008, The Journal of clinical endocrinology and metabolism.

[12]  A. Scillitani,et al.  Short and long-term variations in serum calciotropic hormones after a single very large dose of ergocalciferol (vitamin D2) or cholecalciferol (vitamin D3) in the elderly. , 2008, The Journal of clinical endocrinology and metabolism.

[13]  M. Holick,et al.  Decreased bioavailability of vitamin D in obesity. , 2000, The American journal of clinical nutrition.

[14]  A. Looker.  Body fat and vitamin D status in black versus white women. , 2005, The Journal of clinical endocrinology and metabolism.

[15]  J. Aloia,et al.  Body fat content and 25-hydroxyvitamin D levels in healthy women. , 2003, The Journal of clinical endocrinology and metabolism.

[16]  M. Holick,et al.  Human serum 25-hydroxycholecalciferol response to extended oral dosing with cholecalciferol. , 2003, The American journal of clinical nutrition.

[17]  C. Christiansen,et al.  Serum concentration of vitamin D metabolites during treatment with vitamin D2 and D3 in normal premenopausal women. , 1986, Bone and mineral.