Efficacy and Biosafety of 25-Hydroxyvitamin D3 Biofortified in Egg Yolk in Mice Fed Two Levels of Dietary Fat.

Abstract

Background: Vitamin D inadequacy remains a public health concern, particularly in individuals with obesity. Biofortified eggs with 25-hydroxyvitamin D₃ [25(OH)D₃] may increase intakes of the active metabolite of this nutrient by the public.

Objectives: This study determined efficacy, biosafety, and gut microbiome impact of 25(OH)D₃ biofortified in egg yolk compared with a synthetic form in mice fed a control or high-fat diet (HFD).

Methods: Reg3b^+/- mice (n = 4 males + 4 females/group, 3-5 mo old) were fed a control (CON) or HFD (12% or 60% kcal from fat) supplemented (per kg of diet) with 200 international unit (IU) of 25(OH)D₃ from the control yolk (BAS), the BAS + 500 IU of 25(OH)D₃ from the synthetic form (SUP), or 700 IU of 25(OH)D₃ from the biofortified yolk (YOL) for 8 wk. Body weight, plasma concentrations of 25(OH)D₃, osteocalcin, and receptor activator of nuclear factor kappa β ligand, bone microtomography, bone-related genes and proteins, and colonic and fecal microbiome were examined. Data were analyzed by 2-way analysis of variance.

Results: The HFD-YOL group had 33.4% (P < 0.01) and 39.2% (P < 0.001) higher plasma 25(OH)D₃ concentrations at week 8 than the HFD-SUP and CON-YOL groups, respectively. This elevation was associated with upregulated kidney mRNA levels of cytochrome P450 24A1 (Cyp24a1) and vitamin D receptor (Vdr). Both sources of 25(OH)D₃ unaltered body weights, blood glucose concentration, plasma alkaline phosphatase activity, plasma osteocalcin concentrations, or bone characteristics but altered (P < 0.05) fecal microbiome compositions.

Conclusions: Compared with the synthetic form, 25(OH)D₃ in the biofortified yolk led to higher plasma 25(OH)D₃ concentrations in mice-fed HFD. However, such efficacy in mice fed CON and impacts on fecal microbiome were similar between the 2 sources of 25(OH)D₃. Our finding suggests biosafety and nutritional relevance for future human study of this novel food source of 25(OH)D₃.