Selenium

Selenium yeast (S. cerevisiae), mainly as L-selenomethionine (C₅H₁₁NO₂Se)

Evidence: Strong

Selenium is a trace mineral the body builds into selenoproteins, the antioxidant enzymes (such as glutathione peroxidases) that defend cells against oxidative stress. Two of selenium's recognised roles are especially relevant to the gut: selenium contributes to the protection of cells from oxidative stress and to the normal function of the immune system, much of which operates within the intestinal wall.

We use selenium-enriched yeast, supplying selenium mainly as L-selenomethionine, the form found in food and efficiently absorbed and stored by the body. It rounds out the formula's antioxidant and immune-support nutrients at a sensible, food-equivalent level.

PubMed indexes over 50,000 peer-reviewed papers on selenium.

Selected study

Wang Y, Wu Y, Chen T, Wu X, Yuan W, Zhu Q, Wang X, Zi C. Selenium and Selenoproteins: Mechanisms, Health Functions, and Emerging Applications. Molecules. 2025;30(3):437. doi:10.3390/molecules30030437

Study summary

Study type: Narrative review synthesising laboratory and clinical literature on selenium and selenoproteins.

Observed benefits:

• Organic selenium supports antioxidant defence and helps modulate immune balance.
• Adequate selenium status is associated with broader metabolic and protective functions.

Mechanisms: Selenium is incorporated into about 25 human selenoproteins, including glutathione peroxidases and thioredoxin reductases, which neutralise reactive oxygen species and help regulate immunity.

Safety: Organic selenomethionine has low toxicity at nutritional doses; intake should stay within sensible limits, since selenium has a relatively narrow optimal range.

Evidence strength: Strong biological plausibility, with clinical trials still relatively small; the gut-specific evidence is developing.