Biochemical Comparison of Commercial Selenium Yeast Preparations

Abstract

The trace mineral selenium (Se) is an essential element for human and animal nutrition. The addition of Se to the diet through dietary supplements or fortified food/feed is increasingly common owing to the often sub-optimal content of standard diets of many countries. Se supplements commercially available include the inorganic mineral salts such as sodium selenite or selenate, and organic forms such as Se-enriched yeast. Today, Se yeast is produced by several manufacturers and has become the most widely used source of Se for human supplementation and is also widely employed in animal nutrition where approval in all species has been granted by regulatory bodies such as the European Food Safety Authority (EFSA). Characterisation and comparison of Se-enriched yeast products has traditionally been made by quantifying total selenomethionine (SeMet) content. A disadvantage of this approach, however, is that it does not consider the effects of Se deposition on subsequent digestive availability. In this study, an assessment was made of the water-soluble extracts of commercially available Se-enriched yeast samples for free, peptide-bound and total water-soluble SeMet. Using LC-MS/MS, a total of 62 Se-containing proteins were identified across four Se yeast products, displaying quantitative/ qualitative changes in abundance relative to the certified reference material, SELM-1 (P value <0.05; fold change ≥2). Overall, the study indicates that significant differences exist between Se yeast products in terms of SeMet content, Secontaining protein abundance and associated metabolic pathways.

Selenium in Poultry Nutrition: from Sodium Selenite to Organic Selenium Sources

“…Indeed, the fraction of water-soluble Se in various yeasts varies from 11.5% up to 28.0% (Encinar et al, 2003). It has been confirmed that significant differences exist between Se-yeast products in terms of Se deposition in different cell fractions and Se bioavailability (Fagan et al, 2015).…”

Selenium Analysis and Speciation in Dietary Supplements Based on Next-Generation Selenium Ingredients

“…The bioavailability and biological activity of selenium depend not only on the total ingested amount, but also on its chemical form, solubility, digestibility and accessibility, the presence of other dietary components, and the physiological status of the organism [ 25 , 80 , 81 ]. The organic forms are less toxic and are absorbed more effectively (especially SeMet) than the inorganic ones [ 82 , 83 ].…”

“…The differences imply that the preparations also differ in properties such as bioavailability, bio-efficacy, shelf-life, toxicology, etc. Based on LC–MS/MS and quantitative proteomics, they identified over 62 Se-containing proteins [ 25 ]. Torula yeast ( Candida utilis ) seems to metabolize Se in a specific way, different from Brewer’s yeast ( Saccharomyces cerevisiae ), where the most abundant compound is selenohomolanthionine (SeHLan) [ 87 ].…”

“…One relatively ignored aspect is that Se-yeast, such as selenized Saccharomyces cerevisiae , which is extensively used in nutritional supplements [ 25 ], as well as probiotic bacteria and possibly mushrooms, also contain SeNPs, because they are able to form them as a way of reducing Se toxicity [ 93 , 140 ]. Moreover, SeNPs can be released into the extracellular space in a time-dependent manner.…”

“…Supplementation is recommended for people from selenium-poor regions [ 23 ]. Selenium is used as an ingredient in dietary supplements (DS), both in inorganic forms, such as selenite or selenate salts, mainly for multi-mineral and multivitamin supplements [ 24 ], as well as in organic forms, especially selenium-enriched yeast, as a stand-alone supplement [ 25 ]. However, the dual-side peculiarity of selenium, as an “essential poison”, is linked to a very narrow supplementation physiological window ( Figure 1 ).…”