Impact of vitamin D3 dietary supplement matrix on clinical response.

Context: As a result of research suggesting increased health risk with low serum 25-hydroxycholecalciferol (25(OH)D), health care providers are measuring it frequently. Providers and patients are faced with treatment choices when low status is identified.

Objective: To compare the safety and efficacy of three vitamin D3 dietary supplements with different delivery matrices.

Setting And Design: A 12-week, parallel group, single-masked, clinical trial was conducted in Seattle, Washington and Kailua Kona, Hawaii. Sixty-six healthy adults with (25(OH)D) <33 ng/mL were randomly assigned to take one of three D3 supplements, ie, a chewable tablet (TAB), an oil-emulsified drop (DROP), or an encapsulated powder (CAP) at a label-claimed dose of 10,000 IU/day. Actual D3 content was assessed by a third party and the results adjusted based on the actual D3 content administered. Mean change in 25(OH)D/mcg D3 administered; difference in the proportion of D3 insufficient participants (ie, 25(OH)D ≤30 ng/mL) reaching sufficiency (ie, 25(OH)D ≥30 ng/mL); and mean change in serum 1, 25-dihydroxycholecalciferol were measured.

Results: In two of the three products tested, the measured vitamin D3 content varied considerably from the label-claimed dose. Differences in 25(OH)D/mcg D3 administered were significantly different between groups (P = .04; n = 55). Pairwise comparisons demonstrated DROP resulted in a greater increase than TAB (P < .05) but not than CAP. TAB was not different from CAP. The proportions reaching sufficiency were: 100% (TAB and CAP) and 80% (DROP) (P = .03 between groups; n = 55). 1, 25-Dihydroxycholecalciferol did not change significantly in any group.

Conclusions: Oil-emulsified vitamin D3 supplements resulted in a greater mean change in serum 25(OH)D concentration, but fewer patients reaching vitamin D sufficiency, than chewable or encapsulated supplements.