Selenium yeast

Selenium-enriched yeast extract sold as animal fodder additive

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Selenium yeast is a feed additive for livestock, used to increase the selenium content in their fodder. It is a form of selenium currently approved for human consumption in the EU and Britain.[1] Inorganic forms of selenium are used in feeds (namely sodium selenate and sodium selenite, which appear to work in roughly the same manner). Since these products can be patented, producers can demand premium prices.[2] It is produced by fermenting Saccharomyces cerevisiae (baker's yeast) in a selenium-rich media.[3]

There is considerable variability in products described as Se-yeast and the selenium compounds found within. Many manufacturers and products on the market are simply mixtures of largely inorganic selenium and some yeast.[4] Selenium is found in different forms based upon the food in which it is found. For instance, the form found in mustard and garlic is different from the form found in wheat or corn. In some products, the added selenium is structurally substituted for sulfur in the amino acid methionine, thus forming an organic chemical called selenomethionine via the same pathways and enzymes. Owing to its similarity to sulfur-containing methionine, selenomethionine is mistaken for an amino acid by the yeast anabolism and incorporated in its proteins. It has been claimed that selenomethionine makes a better source of dietary selenium in animal nutrition, since it is an organic chemical compound sometimes found in some common crops such as wheat.[3][5]

## Animal feed additive

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Main article: Selenium in biology

Large amounts of selenium are toxic; however, it is physiologically necessary for animals in extremely small amounts. Many other uncharacterized selenium-containing organic chemicals are also produced by a method similar to that of selenomethionine; some have recently been characterized but remain relatively unknown, such as S-seleno-methyl-glutathione and glutathione-S-selenoglutathione.[3][4] Due to this, the European Union has questioned the safety and potential toxicity of this food supplement for humans, and it may not be used as an additive after 2002.

G.N Schrauzer, who has written two papers about selenomethionine, claims it should be an essential amino acid, and that the product is completely safe.[3] The European Food Safety Authority does allow the use of selenomethionine as a feed additive for animals.[6] Because organic forms of selenium appear to be excreted from the body slower than inorganic forms, products enriched with organic selenium might detrimentally bioaccumulate in the body. Because selenium-enriched foods contain much more selenium than natural foods, selenium toxicity is a potential problem, and such foods must be treated with caution.[4] The EU allows up to 300 micrograms of selenium per day, but one long-term study of selenium supplementation showed no evidence of toxicity at a dose as high as 800 micrograms per day.[7]

An organic selenium-containing chemical found in selenium yeast has been shown to differ in bioavailability and metabolism compared with common inorganic forms of dietary selenium.[8] Dietary supplementation using selenium yeast is ineffective in the production of antioxidants in bovine milk compared to inorganic selenium (sodium selenate).[9] One study examined if increased selenium in the diet of mutant mice (via a selenium yeast product) caused a higher production of selenium-containing enzymes which have an antioxidant effect. The effect was modest.[10]

Selenium supplementation in yeast form has been shown to increase pig selenium-containing antioxidant enzymes,[11] broiler growth and meat quality,[12][13] the shelf life of turkey and rooster semen,[14][15][16] and possibly cattle fertility.[17]

Selenium supplementation in animal feeds may be profitable for agribusinesses. It may be possible to market selenium-fortified foods to consumers as functional foods, such as selenium-enriched eggs, meat,[18][19][20][21] or milk.[9]

## Sel-Plex®

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A patented cultivar of yeast (Saccharomyces cerevisiae 'CNCM I-3060') marketed as Sel-Plex® has been approved for use in animal fodder:

* U.S. Food and Drug Administration approval for use as a supplement to feed for chickens, turkeys, swine, goats, sheep, horses, dogs, bison, and beef and dairy cows.[22]
* Organic Materials Review Institute approval for use as a feed supplement for all animal species.[23]
* As of 2006, the European Food Safety Authority's Scientific Panel on Additives and Products or Substances used in Animal Feed allows the use of Sel-Plex® in animal fodder for poultry, swine, and bovines, as the selenium is not significantly bio-accumulated by the human consumer. Only a small amount should be used when blending animal feeds, 10x the authorized maximum selenium intake causes a drop in production. Appropriate measures to minimize inhalation exposure to the product should be taken.[2]

## Analytical chemistry

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Total selenium in selenium yeast can be reliably determined using open acid digestion to extract selenium from the yeast matrix followed by flame atomic absorption spectrometry.[24] Determination of the selenium species selenomethionine can be achieved via proteolytic digestion of selenium yeast followed by high-performance liquid chromatography with inductively coupled plasma mass spectrometry.[25][26][27]

## See also

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* Nutrition portal

Nutritional muscular dystrophy

## References

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1. ^ "Guidance notes on legislation implementing Directive 2002/46/EC on food supplements".
2. ^ a b European Food Safety Authority (2006). "Opinion of the scientific panel on additives and products or substances used in animal feed on the safety and efficacy of the product Sel-Plex®2000 as a feed additive according to regulation (EC) No 1831/2003". EFSA Journal. 4 (5): 1–40\. doi:10.2903/j.efsa.2006.348.
3. ^ a b c d Schrauzer G (2006). "Selenium yeast: composition, quality, analysis, and safety". Pure Appl Chem. 78: 105–109\. doi:10.1351/pac200678010105.
4. ^ a b c Rayman M, Infante H, Sargent M (2008). "Food-chain selenium and human health: spotlight on speciation". Br J Nutr. 100 (2): 238–253\. doi:10.1017/s0007114508922522. PMID 18346307.
5. ^ Schrauzer GN (2003). The nutritional significance, metabolism and toxicology of selenomethionine. Advances in Food and Nutrition Research. Vol. 47\. pp. 73–112\. doi:10.1016/s1043-4526(03)47002-2. ISBN 9780120164479. PMID 14639782. `{{cite book}}`: `|journal=` ignored (help)
6. ^ Commission of the European Communities. Commission regulation (EC) No 1750/2006 of 27 November 2006 concerning the authorisation of selenomethionine as a feed additive [online]. Available at: http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2006:330:0009:0011:EN:PDF. Accessed January 21.
7. ^ Rayman, Margaret P. (October 2004). "The use of high-selenium yeast to raise selenium status: how does it measure up?". British Journal of Nutrition. 92 (4): 557–573\. doi:10.1079/bjn20041251. PMID 15522125. S2CID 5015850.
8. ^ Schrauzer G. Selenomethionine: A review of its nutritional significance, metabolism and toxicity" J Nutr 2000;130:1653-1656.
9. ^ a b Ravn-Haren G, Bugel S, Krath B, et al. (2008). "A short-term intervention trial with selenate, selenium-enriched yeast and selenium-enriched milk: effects on oxidative defence regulation". Br J Nutr. 99 (4): 883–892\. doi:10.1017/s0007114507825153. PMID 17888202.
10. ^ Lovell M, Xiong S, Lyubartseva G, Markesbery W (2009). "Organoselenium (Sel-Plex diet) decreases amyloid burden and RNA and DNA oxidative damage in APP/PS1 mice". Free Radic. Biol. Med. 46 (11): 1527–1533\. doi:10.1016/j.freeradbiomed.2009.03.008. PMC 2683469. PMID 19303433.
11. ^ Sarkuniene C, Oberauskas V, Baranauskiene D, et al. (2010). "The impact of forage additive Sel-Plex containing organic selenium (Se) on morphological and biochemical blood parameters and activity enzymes GPx and δ-ALRD in fattening pigs". Vet Med Zoot. 50: 88–92.
12. ^ Pappas A, Acamovic T, Surai PF, McDevitt R. Maternal organo-selenium compounds and polyunsaturated fatty acids affect progeny performance and levels of selenium and docosahexaenoic acid in the chick tissues. Poult Sci 2006;85:1610-1620.
13. ^ Zhao L, Xu S, Zhao R, Peng Z, Pan X. "Effects of selenium and methionine supplementation of breeder hen diets on selenium concentration and oxidative stability of lipids in the thigh muscles of progeny. J Food Sci 2009;74:C569-AC574.
14. ^ Dimitrov S, Atanasov V, Surai PF, Denev S (2007). "Effect of organic selenium on turkey semen quality during liquid storage". Anim Reprod Sci. 100 (3–4): 311–317\. doi:10.1016/j.anireprosci.2006.07.007. PMID 16935439.3–4&rft.pages=311-317&rft.date=2007&rft_id=info:doi/10.1016/j.anireprosci.2006.07.007&rft_id=info:pmid/16935439&rft.aulast=Dimitrov&rft.aufirst=S&rft.au=Atanasov,+V&rft.au=Surai,+PF&rft.au=Denev,+S&rfr_id=info:sid/en.wikipedia.org:Selenium+yeast" class="Z3988">
15. ^ Slowinska M, Jankowski J, Dietrich G, et al. (2011). "Effect of organic and inorganic forms of selenium in diets on turkey semen quality". Poult Sci. 90 (1): 181–190\. doi:10.3382/ps.2010-00956. PMID 21177458.
16. ^ Ebeid T (2009). "Organic selenium enhances the antioxidative status and quality of cockerel semen under high ambient temperature". Br Poult Sci. 50 (5): 641–647\. doi:10.1080/00071660903303415. PMID 19904644. S2CID 27779405.
17. ^ Thatcher W, Santos J, Silvestre F, Kim I, Staples C (2010). "Perspective on physiological⁄endocrine and nutritional factors influencing fertility in post-partum dairy cows". Reprod Dom Anim. 45: 2–14\. doi:10.1111/j.1439-0531.2010.01664.x. PMID 24417194.
18. ^ Surai PF, Karadas F, Pappas A, Sparks N (2006). "Effect of organic selenium in quail diet on its accumulation in tissues and transfer to the progeny". Br Poult Sci. 47 (1): 65–72\. doi:10.1080/00071660500475244. PMID 16546799. S2CID 19679504.
19. ^ Navas-Carretero S, Cuervo M, Abete I, Zulet M, Martinez J (2010). "Frequent consumption of selenium-enriched chicken meat by adults causes weight loss and maintains their antioxidant status". Biol Trace Elem Res. 143 (1): 8–19\. doi:10.1007/s12011-010-8831-x. PMID 20809267. S2CID 8561408.
20. ^ Fisinin V, Papazyan T, Surai PF (2009). "Producing selenium-enriched eggs and meat to improve the selenium status of the general population". Crit Rev Biotechnol. 29 (1): 18–28\. doi:10.1080/07388550802658030. PMID 19514900. S2CID 35928188.
21. ^ Mahan D. Organic selenium fed to swine - its potential impact on human health issues. In: Midwest Swine Nutrition Conference. Indianapolis, IN, 2005.
22. ^ Sel-Plex receives authorisation [online]. Available at: http://www.allaboutfeed.net/news/sel-plex-receives-authorisation-id98.html. Accessed January 21.
23. ^ Organic Materials Review Institute. Sel-Plex [online]. Available at: http://www.omri.org/simple-opl-search/results/sel-plex. Accessed January 21.
24. ^ Connolly C, Power R, Hynes M (2004). "Validation of method for total selenium determination in yeast by flame atomic absorption spectrometry". Biol Trace Elem Res. 100 (1): 87–94\. doi:10.1385/bter:100:1:087. PMID 15258322. S2CID 28815488.
25. ^ European Food Safety Authority. Selenium-enriched yeast as source for selenium added for nutritional purposes in foods for particular nutritional uses and foods (including food supplements) for the general population: Scientific opinion of the panel on food additives, flavourings, processing aids and materials in contact with food. EFSA Journal 2008;766:1-42.
26. ^ B'Hymer C, Caruso J (2006). "Selenium speciation analysis using inductively coupled plasma-mass spectrometry". J Chromatogr A. 1114 (1): 1–20\. doi:10.1016/j.chroma.2006.02.063. PMID 16551466.
27. ^ Lobinski R, Edmonds J, Suzuki K, Uden P (2000). "Species-selective determination of selenium compounds in biological materials". Pure Appl Chem. 72 (3): 447–461\. doi:10.1351/pac200072030447.