A Comparison and Safety Evaluation of Micellar versus Standard Vitamin D3 Oral Supplementation in a Randomized, Double-Blind Human Pilot Study

Abstract

The aim of this pilot study was to evaluate and compare bioavailability and safety of two Vitamin D₃ formulations (softgels) in healthy adults, at single daily doses of 1000 and 2500 IU, over a 60-day period. A total of 69 participants were initially screened for eligibility in a double-blind randomized study with a four-arm parallel design; 35 participants were randomized to treatment groups: (1) standard Vitamin D₃ 1000 IU (STD1000), (2) micellar Vitamin D₃ 1000 IU (LMD1000), (3) standard Vitamin D₃ 2500 IU (STD2500), and (4) micellar Vitamin D₃ 2500 IU (LMD2500). Serum Vitamin D concentrations were determined through calcifediol [25(OH)D] at baseline (=before treatment), at day 5, 10, and 15 (=during treatment), at day 30 (=end of treatment), and at day 45 and 60 (=during follow-up/post treatment). Safety markers and minerals were evaluated at baseline and at day 30 and day 60. The pharmacokinetic parameters with respect to iAUC were found to be significantly different between LMD1000 vs. STD1000: iAUC(5-60): 992 ± 260 vs. 177 ± 140 nmol day/L; p < 0.05, suggesting up to 6 times higher Vitamin D₃ absorption of LMD when measured incrementally. During follow-up, participants in the LMD1000 treatment group showed approx. 7 times higher Vitamin D₃ concentrations than the STD1000 group (iAUC(30-60): 680 ± 190 vs. 104 ± 91 nmol day/L; p < 0.05). However, no significant differences were found between the pharmacokinetics of the higher dosing groups STD2500 and LMD2500. No significant changes in serum 1,25(OH)₂D concentrations or other biochemical safety markers were detected at day 60; no excess risks of hypercalcemia (i.e., total serum calcium > 2.63 mmol/L) or other adverse events were identified. LMD, a micellar delivery vehicle for microencapsulating Vitamin D₃ (LipoMicel^®), proved to be safe and only showed superior bioavailability when compared to standard Vitamin D at the lower dose of 1000 IU. This study has clinical trial registration: NCT05209425.

Keywords: bioavailability; cholecalciferol; delivery systems; micelles; pharmacokinetics; supplementation; vitamin D.

Figure 1

Participant flow chart.

Figure 2

Incremental average serum concentrations of 25(OH)D in healthy participants after baseline subtraction at various time points. Mean ± SEM; significance was calculated using the Mann–Whitney test with Holm–Šídák multiple comparison correction.

Figure 3

Incremental average serum concentrations of 1,25(OH)₂D in healthy participants at various time points. Mean ± SEM; significance was calculated using the Mann–Whitney test with Holm–Šídák multiple comparison correction.

Figure 4

Increase in serum (a) 25(OH)D and (b) 1,25(OH)2D concentrations over the 60-day study period. Incremental Area Under Curve (iAUC) values obtained from subtraction of baseline values for each participant at various time points were evaluated. Mean ± SEM; * denotes p ≤ 0.05 using the Mann–Whitney test with Holm–Šídák multiple comparison correction; ns denotes “not significant”.