Enriched selenium yeast

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Selenium yeast is the enriched organic form mostly containing selenomethionine.

Selenium (Se) is an essential trace mineral required for the production of selenoprotein antioxidant enzymes.
For the healthy function of human body selenoproteins like Glutathione peroxidases (GPx) have a vital role in reducing cell-destroying free radicals.
These selenoproteins are also important for proper function of thyroid gland hormones.
Supplements are available in both organic and inorganic forms.
Compared to inorganic forms organic forms have higher absorption and utilization rate.

What is selenium yeast?

Attempts were made to enrich selenium in yeast by fermenting a cane molasses medium with higher levels of inorganic salts of this trace mineral.
Yeast in their growth process transform the inorganic form into organic form by replacing the sulfur molecule with Se molecule in their amino acids.
It is to be noted that simply adding inorganic selenite or selenate salts to the product after fermentation, does not produce enriched yeast.
By such addition the trace mineral will neither be transformed into organic form nor get incorporated into the cells.
In 1970 commercial production of enriched yeast was started.
Commercial product contains 1000 mcg to 2000 mcg of this trace mineral per gram.
Presently reputed manufacturers supply this product containing more than 90% of organic form L-selenomethionine.
Present enriched yeast (Saccharomyces cerevisiae) is a dried, non-viable yeast cultured by fermentation in fed-batch process.
FDA has permitted enriching complete feed for dairy cattle, beef cattle, chicken and turkey with the mineral yeast at levels not exceeding 0.3 ppm (part per million).

Selenium yeast production process

Fed-batch fermentation is the popular process for production of dried non-viable enriched yeast (Saccharomyces cerevisiae).
The salient features of this process is providing incremental amounts of molasses (cane) and sodium selenite into the fermenter.
This minimizes the possibility of detrimental effects on the growth of these yeast cells by one time high quantities of inorganic salts.
Further this facilitates their transformation into organic mineral forms and incorporation into cell material.
Sufficient aeration is given during the fermentation to help its growth.
Low levels of inorganic sulfur are maintained in the medium to enhance Se uptake.
For adjustment of pH during fermentation non sulfur acids like dilute hydrochloric acid are used.
Temperature during yeast fermentation is maintained below 45o C (120oF) to avoid degradation of sodium selenite.
The entire yeast fermentation process may take between 14-16 hours.
By centrifuging, enriched product is now separated from the medium to get a cream.
The extra-cellular materials are removed by rigorous washing (up to seven times) to achieve less than 2% residual inorganic Se salts in the total content of this mineral in the end product.
This cream is now pasteurized for 45 minutes at 85oC and then drum dried to get a non-viable product with 4%-5% moisture

Advantages of selenium yeast

The organic forms are better absorbed and utilized than the inorganic forms.
Inorganic forms can reach toxic levels easily in certain situations.
Among the inorganic forms selenate salts (sodium selenate) are readily absorbed into the body and excreted by kidneys without proper utilization for building selenoprotein.
Selenite salts (sodium selenite) are poorly absorbed (only 50%) though retained for longer time.
The organic forms, basically selenomethionine, are better absorbed and utilized by the body.
In most of the food sources, Se is found mostly as selenomethionine in the intracellular content of the tissues.
In enriched yeast, inorganic salt is transformed mostly into selenomethionine and incorporated into intracellular amino acids.
Experimentally it has been proved that compared to synthetic selenomethionine supplement, the mineral in Brazil nut (intracellular selenomethionine) is better absorbed and utilized.
Akin to food sources enriched yeast is also better absorbed and better utilized.

Enriched yeast uses

Earlier FDA had permitted addition of this yeast product in complete broiler and layer feed. Now addition in cattle feed has been permitted.
Many of the experiments conducted on the nutritional importance of this mineral have used yeast enriched form as supplement.
Selenium yeast is the best form for human supplements with easy absorption and utilization .
Related topics:
Selenium sulfide lotion and shampoo.
Brazil nuts.
Liquid and drops.
Health benefits.
Organic selenium.
Sodium selenite - Sodium selenate.
selenium enriched yeast (current topic).

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