Background/Purpose: Vitamin D deficiency is commonplace throughout the world and is associated with a number of health related consequences. Being a fat-soluble vitamin, speculation has emerged regarding enhanced vitamin D absorption when administered with food. Theorizing that bile salts and digestive lipases enhance vitamin D absorption, we conducted this randomized controlled clinical trial. The objective of this study was to determine if administering vitamin D with the largest meal of the day enhanced vitamin D absorption when compared to a similar group where replacement vitamin D was given following an overnight fast.

Methods: Subjects 18 years of age or greater with a low 25(OH) vitamin D level between 10 and 30 ng/mL were considered for enrollment. A total of 326 subjects were randomly assigned to a vitamin D replacement regimen that was administered either with the largest meal of the day or following an overnight fast. Four separate vitamin D replacement regimens were studied: 50,000 IU vitamin D2 once weekly, 4,000 IU vitamin D3 daily, 2,000 IU vitamin D3 daily, and 1,000 IU vitamin D daily. Results were assessed by improvement in repeat serum 25(OH) vitamin D levels obtained following 12 weeks of replacement therapy. Completers were defined as subjects who were at least 80% compliant with study medication and had a follow-up vitamin D level drawn at study completion. A total of 249 subjects completed the study.

Results: Of the 249 individuals completing the study, 118 took vitamin D with their largest meal while 131 fasted. The mean improvement in 25(OH) vitamin D levels for the “with food” group was 57% (mean baseline: 23.0, mean ending value: 36.1) with a mean raw difference of 13.2 (95% CI 11.2-15.2). Subjects in the fasting group demonstrated a mean improvement in 25(OH) vitamin D levels of 51% (mean baseline: 22.7, mean ending value: 34.2) with a mean difference of 11.5 (95% CI 9.4-13.6). While improvement in 25(OH) vitamin D levels in the entire cohort was 15% greater when administered with food, this improvement was not statistically significant (p=0.26) when compared to repletion following overnight fasting. Subset analysis of the four dosing regimens did demonstrate a statistically significant greater improvement in serum 25(OH) vitamin D levels when replacement was administered with food for the 4,000 IU dosing regimen (p=0.001). In this group the mean change when administered with food was 13.7 (CI 10.3-17.2) while the mean change when fasting was 6.9 (CI 4.6-9.1). Statistical differences were not achieved in the other three dosing regimens.

Conclusion: Administering vitamin D replacement with the largest daily meal resulted in a 15% greater improvement in serum 25(OH) vitamin D levels when compared to repletion following an overnight fast. This difference was not statistically significant. Subset analysis of various dosing regimens identified a statistically significant greater improvement when 4,000 IU of daily vitamin D was administered with the largest meal of the day. We conclude that administering vitamin D with the largest meal of the day may enhance vitamin D absorption, compared to taking it with a morning fast. The difference was modest and not statistically significant.

---

« Back to 2013 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/a-prospective-randomized-open-label-trial-to-evaluate-the-effect-of-food-on-vitamin-d-absorption/