Differential Enhancement of Fat-Soluble Vitamin Absorption and Bioefficacy via Micellization in Combination with Selected Plant Extracts In Vitro

Background/Objectives: Individuals with special metabolic demands are at risk of deficiencies in fat-soluble vitamins, which can be counteracted via supplementation. Here, we tested the ability of micellization alone or in combination with selected natural plant extracts to increase the intestinal absorption and bioefficacy of fat-soluble vitamins. Methods: Micellated and nonmicellated vitamins D3 (cholecalciferol), D2 (ergocalciferol), E (alpha tocopheryl acetate), and K2 (menaquionone-7) were tested in intestinal Caco-2 or buccal TR146 cells in combination with curcuma (Curcuma longa), black pepper (Piper nigrum), or ginger (Zingiber officinale Roscoe) plant extracts. The vitamin uptake was quantified via HPLC-MS, and bioefficacy was assessed via gene expression analyses or the Griess assay for nitric oxide generation. Results: Micellization increased the uptake of vitamin D into buccal and intestinal cells, with vitamin D3 being more efficient than vitamin D2 in increasing the expression of genes involved in calcium transport. The micellization of vitamin E acetate increased its uptake and conversion into biologically active free vitamin E in intestinal cells only. The vitamin K2 uptake into buccal and intestinal cells was increased via micellization. Plant extracts increased the uptake of select micellated vitamins, with no plant extract being effective in combination with all vitamins. The curcuma extract increased the uptake of vitamins D2/D3 but not their bioefficacy. Black pepper and ginger extracts increased the uptake of vitamin E acetate into intestinal cells but failed to increase its conversion into free vitamin E. The ginger extract augmented the uptake of vitamin K2 and increased NO generation additively. Conclusions: Our data substantiate the positive effects of micellization on fat-soluble vitamin absorption and bioefficacy in vitro. While the application of plant extracts in addition to micellization to further increase bioefficacy is an interesting approach, further studies are warranted to understand vitamin-specific interactions and translation into increased bioefficacy.