Effects of a Liquid or Capsule Multivitamin on Vitamin D Status in Active Males and Females

Abstract

Introduction: The purpose of this study was to compare the effects of liquid and capsule multivitamins on 25(OH) vitamin D status following 10-weeks of supplementation.
Methods: Thirty-four recreationally active men (n=14; 21.7±2.9y; 77.5±10.6 kg;) and women (n=20; 23.2±4.7y; 71.1±14.5kg) participated in this randomized, double- blind, placebo- controlled study. Before and after a 10-week intervention, participants provided a fasted blood sample and were randomly assigned to a liquid multivitamin supplement (LIQ; n=11), multivitamin capsule (CAP; n=11), or placebo group (CON; n=12). Participants took their respective supplement daily for 10 weeks with the LIQ and CAP supplement both containing 268 IU of vitamin D. Plasma samples were assayed for 25(OH) vitamin D concentrations. Data were analyzed using a two-way repeated measures analysis of variance (ANOVA). Results: A main effect for time (p=0.002) was seen with 25(OH) vitamin D concentrations significantly lower (∆: -7.8±14.9ng/mL) at post-testing with groups collapsed. Further, there were no significant differences between treatments (p=0.820) in 25(OH) concentrations suggestion no effect of LIQ or CAP compared with CON.
Conclusion: It appears that a chronic low dose of vitamin D in liquid or capsule form is insufficient to maintain or elevate 25(OH)D concentrations in active young adults.