Bioequivalence Studies of Vitamin D Gummies and Tablets in Healthy Adults: Results of a Cross-Over Study

The objective of this investigation was to compare bioavailability between single oral dose Vitamin D (vitD) gummies vs. tablets in healthy adults. An initial crossover, randomized clinical trial involving healthy adults ( = 9) was conducted followed by a larger, confirmatory study ( = 31). Healthy participants aged 18-45 years with body mass index (BMI) 18-30 without anemia or vitD deficiency were randomized to receive 20,000 international units (IU) vitD as single dose gummies or tablets with serial samples obtained to measure plasma vitD at baseline, 3, 6, 10, 24, and 48 h followed by a 2-week washout period. The same participants then crossed over to receive 20,000 IU vitD in the form not previously given, with sampling at the same time points. Deidentified blood samples were analyzed for vitD concentration by liquid chromatography (LC)-mass spectroscopy. In Study 1, results suggested bioavailability was greater with gummies compared with tablets, (effect size 1.08 at 24 h). In Study 2, the area under the concentration curve (AUC) was higher with gummies than tablets (gummy mean (95% CI): 1474 ng·/mL (1393-1555); tablet mean (95% CI): 774 ng·h/mL (693-855), < 0.0001). Average peak blood concentration (C) values were significantly higher with gummies (gummy: 47.3 ng/mL; tablet: 23.4 ng/mL; < 0.0001). VitD gummies had greater bioavailability than tablets with higher vitD concentrations over time, which may have implications for achieving vitD sufficiency.