What is selenium-enriched yeast?

Later, through many studies, it was found that organic selenium does indeed have higher biological activity than inorganic selenium, making it easier for the body to absorb and utilize, with less toxicity and environmental pollution. However, inorganic selenium has the advantage of being cheaper.

There are many types of organic selenium, such as selenium-enriched yeast, selenium-enriched mushroom powder, selenium-enriched malt, and selenium-enriched algae. Among these, selenium-enriched yeast is currently considered the ideal selenium supplement for both humans and animals. This chapter will introduce the nutritional value, safety performance, production, and testing of selenium-enriched yeast to help people gain a basic understanding of its biological efficacy, along with brief mentions of other organic selenium supplements.

Selenium-enriched yeast is currently the most widespread and ideal organic selenium supplement.

Experts Schrauzer and White (1983) conducted in-depth research on the biochemical properties of organic and inorganic selenium. They suggested that compared to inorganic selenium, organic selenium has higher biological activity and lower toxicity, with its bioactivity being approximately 100 times greater. Westermark (1987) found through research that the organic selenium content in selenium yeast is relatively high, making it an ideal organic selenium supplement.

As early as the 1980s, Chen Yuezeng suggested from a nutritional perspective that supplementing daily intake with appropriate amounts of selenium yeast is beneficial (Chen Yuezeng, et al., 1985). Currently, countries such as the United States, Canada, and Japan have produced medicinal selenium yeast, which is sold in pharmacies. Meanwhile, selenium intake in the Chinese diet is generally low, so it is even more important for Chinese people to pay attention to selenium supplementation.

Li Aifen et al. (2004) stated that to date, there are roughly three forms of selenium supplementation: 1) supplementing with inorganic selenium compounds, although these compounds are toxic and improper dosages can easily cause adverse side effects; 2) supplementing with synthetic organic selenium compounds, primarily through injection, in hopes that the selenium will be released gradually within the body for long-term effects, though the injection method limits its application; 3) supplementing with selenium yeast, where selenium in the yeast cells is bound to proteins in the form of selenoamino acids, resulting in very low toxicity and easy absorption, making it the ideal form of selenium supplementation for humans and animals worldwide.

Jin Fengqiu and Jin Qirong (2000) pointed out that selenium yeast can enhance the immune system of both humans and animals, helping to fight disease, mobilize anti-cancer factors, and control tumor growth. It also eliminates free radicals within the body, combats aging, and regular consumption of selenium yeast contributes to health and longevity. Selenium yeast has become an internationally recognized trace element fortifier.

Wu Yingde and Wu Kaiguo (2002) proposed, based on epidemiological, laboratory, and clinical studies, that selenium yeast is currently considered the best form of selenium supplementation. Numerous reports have demonstrated its safety and effectiveness. As for sodium selenite, no evidence currently suggests it is better than selenium yeast. According to existing research on the prevention and treatment of colon, lung, prostate, and liver cancers, the optimal dosage of selenium-enriched yeast is 200 μg per day, which has excellent tolerance and provides the strongest protection against tumor development in individuals with low plasma selenium levels.

Chen Changlan et al. (2016) and Whanger (2004) also agreed that selenium-enriched yeast is the most common selenium supplement on the market and is the primary form used in clinical trials.

Liu Jie et al. (2009) noted that selenium-enriched yeast is easy to cultivate, grows rapidly, and absorption tests using 77Se labeling showed that yeast can absorb selenium at rates of 75% to 90%. This makes it the preferred form of selenium supplementation. Yeast has a high capacity for selenium enrichment and provides a range of nutrients, including proteins, amino acids, and vitamins, making selenium yeast an efficient and low-toxicity organic selenium supplement, drawing attention from researchers both domestically and internationally (Zhang Guorong, et al., 2009).

Wei Shuyi et al. (2012) pointed out that when sulfur in methionine is replaced by selenium, selenomethionine is formed, which is the organic selenium compound with the highest bioavailability. After absorption, the body can form a selenium reserve pool. Selenium-enriched yeast uses yeast as a carrier to convert inorganic selenium, which is difficult to absorb, into easily absorbed organic selenium in the culture medium. This makes selenium-enriched yeast a widely researched food selenium supplement.

Foreign scholars also generally agree that selenium yeast is the ideal human selenium supplement. Perucchietti et al. (2013) noted that, based on existing literature and data from published studies, selenomethionine in selenium yeast is widely considered the most effective and active compound. Murphy (2016) stated that selenium-enriched yeast is the most bioavailable source of organic selenium. Although many other products are labeled as organic selenium, the production methods and basic chemical principles behind these claims suggest otherwise.

Therefore, Jia Hongfeng et al. (2005) proposed that China, being a selenium-deficient country, cannot meet its people's selenium needs through natural foods alone. Thus, selenium-enriched yeast, as a safe and effective selenium source, has great development potential.

What is selenium-enriched yeast?

Regarding selenium-enriched yeast (abbreviated SY or SeY), experts from various fields, including nutrition, pharmacology, and microbiology, have their interpretations. However, they all converge on one concept: selenium-enriched yeast is an organic selenium product produced by converting and enriching inorganic selenium using yeast as a carrier.

Scholars Shen Yinshu and Ding Hongbiao (2008) defined selenium-enriched yeast as a microbial fermentation product where inorganic selenium, such as sodium selenite, is added during yeast cultivation, which is then converted into organic selenium and enriched within the yeast cells.

Fu Ruijuan et al. (2011) considered selenium-enriched yeast to be a biological preparation. During yeast cultivation, selenium is absorbed and utilized by the yeast as it grows, causing selenium to bind organically with proteins and polysaccharides in the yeast, transforming it into bio-selenium. This eliminates the toxic side effects and gastrointestinal irritation associated with chemical selenium (like sodium selenite), making it more efficiently and safely absorbed by the body.

In 2007, the U.S. Food and Drug Administration defined feed-grade selenium-enriched yeast as inactive dry yeast cultured using batch fermentation. During fermentation, cane molasses and sodium selenite are gradually added to minimize the adverse effects of sodium selenite on yeast growth and ensure optimal binding of inorganic selenium to organic material within the yeast cells. Any residual inorganic selenium is removed through a rinsing process, ensuring it accounts for no more than 2% of the total selenium content in the final product (Shen Yinshu, et al., 2008).

Development, research, and production history of selenium-enriched yeast

The development of selenium-enriched yeast began in the early 1970s.

Early research on yeast-enriched selenium traces its development to the U.S., which led the way in this field and launched the first batch of selenium-enriched yeast in 1974 (Schrauzer, 2006).