25-Hydroxyvitamin D3 Bioenriched Chicken and Eggs Maintained Vitamin D Status Over the Winter in Healthy Adult Males and Females: A Randomized Controlled Trial.

BACKGROUND: Vitamin D insufficiency remains a concern in the U.S. due to limited natural food sources and insufficient UVB exposure. Biofortification of poultry and eggs with vitamin D or 25(OH)D is a potential strategy to improve vitamin D status. OBJECTIVE: To assess whether biofortification of chicken and eggs with 25(OH)D3 increases total serum 25(OH)D concentrations compared to vitamin D3 supplementation. METHODS: Participants (n=57) were randomized into three groups for an 8-week winter intervention. Participants received chicken during weeks 1-8 and eggs during weeks 5-8. The 25D3 Group (n=19) received 25(OH)D3 biofortified chicken and eggs with daily placebo pills. The D3 Group (n=19) received control chicken and eggs with a daily vitamin D3 supplement (1000 IU/d). The Placebo Group (n=19) received control chicken and eggs with daily placebo pills. Biweekly blood samples were collected to measure vitamin D metabolites using LC-MS/MS. Changes in vitamin D metabolites over time were assessed using mixed-effects models. RESULTS: Vitamin D3 supplementation significantly increased total serum 25(OH)D by 4.3 ng/mL over 8 weeks (95% CI: 1.0, 7.5; P < 0.05), while 25(OH)D3 biofortification maintained serum 25(OH)D at baseline concentrations. Individuals in the Placebo Group experienced a significant decline in serum 25(OH)D concentrations by 4.4 ng/mL (95% CI: -7.7, -1.7; P < 0.05). CONCLUSIONS: 25(OH)D3 biofortification of chicken and eggs prevented the seasonal decline in serum 25(OH)D observed in healthy young adults not taking vitamin D3 supplements but was not as effective as a daily 1000-IU vitamin D3 supplement. CLINICAL TRIAL REGISTRY: This study was registered at https://clinicaltrials.gov/study/NCT05248737.