Metabolism of l-Selenomethionine and Selenite by Probiotic Bacteria: In Vitro and In Vivo Studies

Abstract

Since selenium supplements have been shown to undergo biotransformation in the gut, probiotic treatment in combination with selenium supplements may change selenium disposition. We investigated the metabolism of L-selenomethionine (SeMet) and selenite by probiotic bacteria in vitro and the disposition of selenium after probiotic treatment followed by oral dosing with SeMet and selenite in rats. When SeMet was incubated anaerobically with individual antibiotic-resistant probiotic strains (Streptococcus salivarius K12, Lactobacillus rhamnosus 67B, Lactobacillus acidophilus L10, and Bifidobacterium lactis LAFTI® B94) at 37°C for 24 h, 11-18% was metabolized with 44-80% of SeMet lost being converted to dimethyldiselenide (DMDSe) and dimethylselenide (DMSe). In similar incubations with selenite, metabolism was more extensive (26-100%) particularly by the lactobacilli with 0-4.8% of selenite lost being converted to DMSe and DMDSe accompanied by the formation of elemental selenium. Four groups of rats (n = 5/group) received a single oral dose of either SeMet or selenite (2 mg selenium/kg) at the time of the last dose of a probiotic mixture or its vehicle (lyoprotectant mixture used to maintain cell viability) administered every 12 h for 3 days. Another three groups of rats (n = 3/group) received a single oral dose of saline or SeMet or selenite at the same dose (untreated rats). Serum selenium concentrations over the subsequent 24 h were not significantly different between probiotic and vehicle treated rats but appeared to be more sustained (SeMet) or higher (selenite) than in the corresponding groups of untreated rats. Probiotic treated rats given SeMet also had selenium concentrations at 24 h that were significantly higher in liver and lower in kidney than untreated rats given SeMet. Thus, treatment with probiotics followed by SeMet significantly affects tissue levels of selenium.

Selenium and Human Health: Witnessing a Copernican Revolution?

“…Indiscriminate use of dietary Se supplements, even at doses recently considered to be safe may lead to severely affected redox status with subsequent adverse health effects, as also suggested by an increasing body of epidemiologic evidence. Moreover, Se has other effects yet uninvestigated, for example the potential of epigenetic regulation of DNA and histones [251][252][253] or interaction with the gut microbiota [254][255][256], which need to be carefully addressed. At the same time, the unclear interactions between Se and heavy metals also need clarification.…”

Selenium Supplementation and Prostate Health in a New Zealand Cohort

“…This means that part of the supplemented selenium would have passed though different routes in addition to replenishing the serum component. Among such possible selenium channeling routes may include, excretion [54]; metabolism by gut biota to forms that reduce absorption into circulation [55]; used up for toxicity modulation [56]; channeled towards other tissue optimization [57] including that of the prostate [58][59][60]; or the selenomethionine component in the selenized yeast [61] getting non-specifically incorporated into a wide range of tissue proteins in place of methionine [62,63]. Takata et al, 2009 have shown that serum selenium level is a reflection of the levels in the prostate [59].…”

Selenomethionine protects hematopoietic stem/progenitor cells against cobalt nanoparticles by stimulating antioxidant actions and DNA repair functions

“…Sham-treated rats received 50 μL of vehicle alone. In addition, rats received an oral dose of SeMet (2 mg SeMet/kg body weight/day) according to methods described in previous studies [ 26 , 27 ]. All rats were sacrificed three weeks after the final injection of CoNPs or vehicle alone.…”