Selenium-enriched micro-organisms (ProbioSel®) as organic source of selenium for human Nutrition

One of the paths explored to obtain compositions rich in selenium consists in enriching certain microorganisms with organic selenium from inorganic selenium. These microorganisms, once enriched, can serve as dietary supplement for the preparation of food products.

The microorganisms enriched with selenium are prepared from inorganic selenium uniquely. Thus, the source of selenium the most often used consists in sodium selenite or selenate solubilised in culture media of microorganisms.

Up to now Selenium enrichment of microorganisms is based on incorporation of sodium selenite in the culture medium:

From 0.2% to 1% selenium equivalent in the culture medium leads to :

  • mainly selenomethionine in yeast (54 to 74% of total Se, depending on culture conditions and analytical determination)
  • mainly selenocysteine in bacteria (60% of 75Se in intracellular proteins)

The microorganisms thereby enriched, although having synthesised satisfactory quantities of organic selenium assimilable by the human body, often have a high residual level of non-transformed inorganic selenium, which can prove to be dangerous for the consumer. In addition, the bacteria, such as those of the genus Lactobacillus, mainly transform this inorganic selenium into selenocysteine and not into selenomethionine.

It has thus appeared that the enrichment of microorganisms with selenomethionine from organic compounds such as NutraSelen makes possible the production of microorganisms containing mainly SeMet the source of selenium the most bio-available for humans and animais and practically exempt of inorganic selenium.

It has thus been demonstrated that a supplementation of the diet with L(+)-selenomethionine is much less toxic and has a better bioavailability than an intake in the form of sodium selenite (Mony, MC et al.; J. of Trace Elem. Exp. Med.; 2000; 13; 367-380).

A suitable supply of organic selenium can be found in the higher plants (wheat, maize, soya especially), in which more than 80% of the selenium is constituted by L(+)-selenomethionine (Schrauzer, G.N.; J.Am.Coll. Nutrit,; 2001; 20; 1; 1-4). However the selenium concentration in these plants is not sufficient to be able to produce easily, and at less cost, food additives.