Vitamin D₃ is known to be liposoluble and its release could be a factor limiting the rate of absorption. It was presumed that the presence of fat could favor absorption of vitamin D₃. However, as bioavailability is related not only to the active molecules but also to the formulations and excipients used, the optimization of the pharmaceutical form of vitamin D₃ is also important. The objective of this study was to evaluate if there is a food effect on absorption when a high dose of vitamin D₃ is completely solubilized in an oily solution. In the present cross-over study, 88 subjects were randomized and received a single dose of 50,000 IU of vitamin D₃ in fasting state or with a standardized high-fat breakfast. Assessment of serum concentrations of 25 hydroxyvitamin D₃ (25(OH)D₃) was performed three, five, seven, 14, 30 and 60 days after supplementation. In fed and fast conditions, the 25(OH)D₃ serum concentrations were significantly higher than the baseline value three days after administration and remained significantly higher during the first month. No significant difference between fasting vs. fed conditions was observed. It is therefore concluded that the vitamin D₃ absorption from an oily solution was not influenced by the presence or absence of a meal.
Keywords: 25-hydroxyvitamin D3; absorption; fasting; high fat.