ChatGPT Answers About Different Forms of Selenium Supplements

In our last article, we asked ChatGPT about the health benefits of selenium supplements in Europe. This time, we asked what is the best form of selenium supplement?

ChatGPT about selenium
We asked ChatGPT for information about the various forms of selenium supplements.

ChatGPT answered that the best form of selenium supplement depends on various factors. These factors include individual health needs, dietary habits, and preferences. Each different form of selenium supplement has its own set of advantages and considerations.

  • Selenomethionine: This form of selenium is found in foods like Brazil nuts, grains, and legumes. The body absorbs selenomethionine well.
  • Sodium selenite: This is an inorganic form of selenium. It is generally considered to have lower bioavailability compared to organic forms like selenomethionine and selenium yeast.
  • Selenium yeast: Selenium yeast is produced by fermenting the yeast Saccharomyces cerevisiae in the presence of selenium. It contains various species of selenium including selenomethionine. The yeast is inactivated in the supplements.

Editor’s note: The presence of various other species of selenium in the selenium yeast may be important for cancer prevention. By other species, we mean the selenium species other than the selenomethionine that is in the selenium yeast supplements.

  • In the Nutritional Prevention of Cancer study, researchers administered 200 mcg/day of selenium-enriched yeast for an average of 5.4 years. The study results showed a significant reduction of colorectal, lung, prostate, and total cancer incidence [Clark 1996].
  • In the SELECT study, researchers administered selenium in the form of selenomethionine, 200 mcg/day. The supplementation with selenomethionine alone and also together with vitamin E did not show any reduction of the risk of colorectal, lung, or prostate cancer after 5.5 years of follow-up [Lippman 2009].

Thus, it seems that the protective effect against cancer may have come from one or more of the other selenium species in the selenium yeast preparation, not from the selenomethionine in the preparation [Bjørnstedt 2010].

ChatGPT Advice When Choosing a Selenium Supplement

We should consider the following factors:

Bio-availability: Organic forms like selenomethionine and selenium yeast are generally considered more bioavailable than inorganic forms.

Editor’s note: Pure selenomethionine and selenium yeast are both well absorbed. The difference may be in the clinical effect. Richie et al showed that selenium yeast but not pure selenomethionine was associated with significant reductions in biomarkers for oxidative stress [Richie 2014].

Dosage: An individual’s need for supplemental selenium varies according to the selenium content of the soil and the food in a particular region. ChatGPT warns that excessive selenium intake can lead to toxicity. We should not exceed recommended levels.

Editor’s note: In selenium-poor regions of the world, poor health because of selenium deficiency seems to be a considerably greater problem than excessive selenium intake is [Schomburg 2021]. Again, it is important to talk with a qualified healthcare professional about the need for selenium supplementation.

Quality and Purity: It is important to choose a reputable brand to ensure the quality and purity of the supplement. If possible, we should look for a product that have been tested by third-party organizations for quality assurance.

Editor’s note: We want documented evidence for the absorption, bioavailability, and clinical efficacy of the selenium yeast formulation. Different manufacturers’ formulations of the selenium yeast can produce products with differing compositions of the various selenium species [Rayman 2004].

Tolerability: Some individuals may experience gastrointestinal discomfort or allergic reactions to certain forms of selenium. If you have a sensitive reaction to a selenium supplement, you should consult with a healthcare professional.

Editor’s note: The following are recognizable signs of a possible overdosing with selenium:

  • brittle hair and nails and loss of hair and nails
  • garlic breath odor
  • gastrointestinal disturbances
  • skin rashes
Conclusion: ChatGPT and Selenium Supplementation

ChatGPT advises consulting with a healthcare professional to determine whether you need a selenium supplement and to discuss the appropriate form and dosage for your individual health circumstances.

Editor’s note: It is important to distinguish between marketing claims and scientific evidence for a selenium supplement’s absorption and health benefits [Rayman 2004].


Björnstedt M, Fernandes AP. Selenium in the prevention of human cancers. EPMA J. 2010 Sep;1(3):389-95.

Clark LC, Combs GF Jr, Turnbull BW, Slate EH, Chalker DK, Chow J, Davis LS, Glover RA, Graham GF, Gross EG, Krongrad A, Lesher JL Jr, Park HK, Sanders BB Jr, Smith CL, Taylor JR. Effects of selenium supplementation for cancer prevention in patients with carcinoma of the skin. A randomized controlled trial. Nutritional Prevention of Cancer Study Group. JAMA. 1996 Dec 25;276(24):1957-63.

Lippman SM, Klein EA, Goodman PJ, et al. Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA. 2009;301(1):39-51.

Rayman MP. The use of high-selenium yeast to raise selenium status: how does it measure up? Br J Nutr. 2004 Oct;92(4):557-73.

Richie JP Jr, Das A, Calcagnotto AM, Sinha R, Neidig W, Liao J, Lengerich EJ, Berg A, Hartman TJ, Ciccarella A, Baker A, Kaag MG, Goodin S, DiPaola RS, El-Bayoumy K. Comparative effects of two different forms of selenium on oxidative stress biomarkers in healthy men: a randomized clinical trial. Cancer Prev Res (Phila). 2014 Aug;7(8):796-804.

Schomburg L. Selenium deficiency due to diet, pregnancy, severe illness, or covid-19-a preventable trigger for autoimmune disease. Int J Mol Sci. 2021 Aug 8;22(16):8532.

The information presented in this review article is not intended as medical advice. It should not be used as such.

15 December 2023

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