Effects of antibiotics on degradation and bioavailability of different vitamin E forms in mice.

Tocopherols (T) and tocotrienols (T3), all existing in α, β, γ, and δ-forms, are the eight forms of vitamin E (VE). In this study, we investigated the effects of gut microbiota on the degradation and tissue levels of different VE forms by treating mice with antibiotics in drinking water for 12 days. The mice also received an intragastric (i.g.) dose of VE mixture (mVE; α-T, γ-T, δ-T, γ-T3, and δ-T3, each at a dose of 75 mg/kg) every morning. Antibiotic treatment significantly increased the blood levels of all VE forms in mice that received an i.g. dose of mVE in the morning, 3 h before sacrifice. Without this morning dose, the blood levels of α-T were at the normal physiological levels, but those of the other VE forms were much lower; and the levels of all VE forms were not significantly affected by antibiotics. The liver levels of these VE forms were generally higher and followed the same pattern as the serum. On the contrary, the levels of most side-chain degradation metabolites of VE forms in the serum, liver, kidney, urine, and fecal samples were significantly decreased by antibiotics. The increased bioavailability of VE by antibiotics is probably due to increased absorption of VE or its decreased degradation by gut microbes. The results demonstrate the important roles of gut microbiota in the degradation of VE and in decreasing the bioavailabilities of VE forms. © 2019 BioFactors, 45(3):450-462, 2019.