The effects of different forms of vitamin E on gut microbiota, mechanisms, and implications in disease prevention

The gut microbiota plays an important role in host health and dysbiosis contributes to disease development. Natural forms of vitamin E consist of eight lipophilic antioxidants, i.e., alpha-, beta-. gamma- and delta-tocopherol (αT, βT, γT and δT) and alpha-, beta-. gamma- and delta-tocotrienol (αTE, βTE, γTE and δTE). Vitamin E forms and their metabolites including 13'-carboxychromanols (13'-COOHs) have been shown to possess anti-inflammatory activities. Interestingly, recent human and animal studies reveal that vitamin E forms and δTE-13'-COOH (metabolite of δTE) can modulate gut microbiota. Specifically, supplementation of αT, γT, tocotrienols or δTE-13'-COOH elevated some beneficial bacteria or attenuated disease-associated decrease of probiotics including butyrate producers. This review focuses on the current knowledge of the effects of different forms of vitamin E and δTE-13'-COOH on gut microbiome. Although the mechanisms underlying modulation of gut microbiota remain to be determined, this author proposes that promotion of beneficial gut microbes by vitamin E forms may in part be rooted in their antioxidant and anti-inflammatory activities as well as protection of intestinal barrier integrity, and that the modulatory effects on gut microbes likely contributes to vitamin E-facilitated disease prevention. Finally, this review discusses knowledge gaps and future research efforts needed to uncover how vitamin E forms interact with gut microbiota and utilize such knowledge for improving human health.