Effects of 12‐week multivitamin supplementation on serum 25‐hydroxycholecalciferol levels in pre‐menopausal females

PURPOSE We sought to examine if multivitamin supplementation (MV) affected serum 25‐hydroxycholecalciferol (25OHD) levels in pre‐menopausal women during a 12‐week intervention. METHODS Women between the ages of 21–40 years who were apparently healthy and refrained from MV supplementation at least one month prior to the trial were recruited from the local Auburn, AL community. PRE testing occurred between the hours of 0600–0900 5±2 days following the menses phase of each participants’ last menstrual cycle and involved a fasted blood draw, body mass assessment, and blood pressure assessment. Following PRE testing, participants were randomly assigned in a double‐blinded fashion to either the MV group (n=43, 24±4 years old, 23.3±2.9 kg/m 2 ) or placebo group (n=51, 23±3 years old, 23.1±2.7 kg/m 2 ). MV capsules (per 2 beadlets‐in‐capsule serving) contained 50 mcg (2000 IU) of vitamin D3, 6.7 mg alpha tocopherol (10 IU) of vitamin E as mixed tocopherols, 90 μg vitamin K2 MK7, 600 μg (1000 DFEs) 5‐methyltetrahydrofolate, 8 μg B12, 8 mg iron, 50 mg magnesium, 1 mg boron, and 320 mg omega‐3 fatty acids. Placebo capsules contained safflower oil and cellulose beadlets. Participants in both groups were instructed to consume two capsules per day with breakfast for 12 weeks. Following the 12‐week intervention, participants reported to the laboratory between the hours of 0600–0900 5±2 days following the menses phase of the last menstrual cycle for the POST assessment which replicated PRE testing procedures. Serum 25OHD analysis was performed in a blinded fashion at a CLIA‐certified hematology laboratory (East Alabama Medical Center, Opelika, AL, USA). All dependent variables were analyzed using 2×2 (supplement × time) repeated measures ANOVAs. LSD post hoc tests were performed when significant interactions were observed, and statistical significance was established at p<0.05. RESULTS Significant supplement×time interactions were observed for dietary vitamin D intake (p<0.001) and serum 25OHD levels. Four‐day food recalls indicated MV supplementation significantly increased the PRE to POST intakes of vitamin D levels (1.7±2.1 mcg/d to 51.2±1.4 mcg/d, p<0.001), whereas no change in intake was observed in the placebo group. Notably, vitamin D intakes were similar at PRE and POST in the MV group when removing values added through supplementation suggesting that increases in this group were strictly due to supplementation. MV supplementation also increased serum 25OHD from PRE to POST (32.7±13.2 ng/mL to 47.0±16.2 ng/mL, p<0.001), whereas no change occurred in the placebo group. Interestingly, 78% of MV participants presented low serum 25OHD levels (<40 ng/mL) prior to supplementation, and MV supplementation reduced this prevalence to merely 30%. Conversely, these prevalence rates were above 70% in the placebo group prior to and following the intervention. CONCLUSIONS These data clearly demonstrate that MV supplementation significantly increases serum 25OHD levels. Support or Funding Information This study was funded by a grant awarded to MDR and KCY by Ritual, Inc. Support was also provided by The GHT Companies, and Kappa BioSciences.Legend: Bar graphs are plotted as means ± standard deviation values (which are also indicated numerically at the bottom of each bar), and gray data points indicate individual respondents. The significant group × time (G × T) interaction prompted LSD post hoc tests within each group and between groups at each time point. This metric increased from PRE to POST in MV group (“*”, p<0.05). Additionally, POST values were clearly elevated in the MV group (“#”, p<0.05).