The rationale for taking a selenium-enriched yeast preparation: one or more of the selenium compounds in the preparation other than selenomethionine may be the selenium species that has specific effects against cancer. This is an area for further research.
This week, we focus on studies conducted with a selenium-enriched yeast preparation containing at least 20 different species of selenium in addition to selenomethionine [Bendahl & Gammelgaard 2004].
Randomized, double-blind, controlled clinical trials are the gold standard method for testing the safety, absorption, and efficacy of nutritional supplements and medical drugs. Below, we summarize some of the important clinical trials of nutritional interventions using selenium-enriched yeast.
Anti-cancer Effect of Selenium-enriched Supplements
Note that the SELECT selenium and vitamin E and prostate cancer study used a 100% selenomethionine preparation. The selenomethionine deposits mainly in the muscle and has not shown any anti-cancerous effect [Lippman 2009].
In the Nutritional Prevention of Cancer trial, by contrast, the researchers used a selenium-enriched yeast preparation containing a variety of selenium species. The study outcome data showed, in the selenium-enriched yeast treatment group, significant reductions in total cancer mortality, total cancer incidence, and incidence of lung, colorectal, and prostate cancers [Clark 1996].
Antioxidant Effect of Selenium-enriched Yeast Supplements
Richie et al conducted a randomized, double blind, placebo-controlled trial of a selenium yeast supplement (200 or 285 mcg/day) and a selenomethionine supplement (200 mcg/day) daily for nine months in 69 healthy men. The researchers found that the selenium-enriched yeast supplements were significantly associated with reductions in biomarkers of oxidative stress. This was not the case for the selenomethionine supplementation. The researchers suggested that selenium-enriched yeast supplements contain selenium compounds other than selenomethionine that may account for the reduction in oxidative stress [Richie 2014].
Absorption of Selenium-enriched Yeast Supplements
Selenium absorption, excretion, and retention are dependent upon the chemical form of the selenium. In a study of 12 healthy male volunteers, aged 26-51 years, who had been regularly taking large amounts of dietary supplements containing selenium, researchers analyzed blood, urine, and faeces samples at regular intervals for up to 14 days. They concluded that selenium from a selenium-enriched yeast supplement is well absorbed and retained [Bügel 2004].
Hurst et al carried out a randomized, double-blind, placebo-controlled selenium intervention in 119 healthy men and women aged 50-64 years living in the United Kingdom. The study participants received daily placebo or selenium-enriched yeast tablets containing 50, 100, or 200 micrograms of selenium. At baseline, the study participants’ plasma selenium status was, on average, 95.7 mcg/L. They had an estimated dietary selenium intake of approximately 55 mcg/day [Hurst 2010].
Ten weeks of daily supplementation with a selenium-based yeast product resulted in the following increases in plasma selenium status [Hurst 2010]:
- 50 mcg/day: 118.3 mcg/L
- 100 mcg/day: 152.0 mcg/L
- 200 mcg/day: 177.4 mcg/L
The plasma levels of selenoprotein P, the primary selenium transporter in the body, increased significantly in all intervention groups [Hurst 2010]. Based on the selenoprotein P data in this study, supplementation with either 50 or 100 mcg Se/day results in improvements in selenium status in a British cohort with suboptimal selenium status [Hurst 2010].
The Hurst study data are interesting in light of the conclusions from a multinational, observational cohort study that enrolled patients with worsening heart failure [Bomer 2020]. In that study, serum selenium concentrations less than 70 mcg/L (deficiency status) were seen in heart failure patients who had worse New York Heart Association class, more severe signs and symptoms of heart failure, poorer exercise capacity, and poorer quality of life.
More importantly, the researchers reported that heart failure patients with serum selenium concentrations between 70 and 100 mcg/L had similar adverse associations. This suggests that serum selenium values less than 100 mcg/L might be regarded as sub-optimal [Bomer 2020].
Cardiovascular disease and selenium-enriched yeast supplements
Significantly reduced cardiovascular mortality persisted after 12 years in elderly Swedish citizens supplemented daily for the first four years with a combination of selenium-enriched yeast and Coenzyme Q10. Researchers also observed the significant reductions of cardiovascular mortality in subgroups of study participants with diabetes, hypertension, ischemic heart disease, and impaired cardiac function [Alehagen 2018].
Diabetes Risk and Selenium-enriched Yeast Supplements
In a randomized, double-blind, placebo-controlled trial, researchers randomly assigned 501 elderly volunteers to a six-month intervention with a placebo yeast or to 100, 200 or 300 mcg selenium/day from selenium-enriched yeast.
The study data showed that the selenium supplementation had no effect on adiponectin levels after six months of treatment. That is to say, the selenium supplementation did not show a diabetogenic effect in a sample of elderly individuals with relatively low selenium status at baseline [Rayman 2012].
Kidney Disease and Selenium-enriched Yeast Supplements
Patients with chronic kidney disease have an increased incidence of cancer.
Long periods of hemodialysis treatment are associated with DNA damage because of the associated oxidative stress. In a study of 42 chronic kidney disease patients and 30 healthy controls, researchers investigated the effect of 200 micrograms of a selenium-enriched yeast preparation daily for three months on the prevention of oxidative DNA damage in white blood cells of chronic kidney disease patients on hemodialysis. The study data showed that white blood cell DNA damage is higher in chronic kidney disease patients on hemodialysis than in healthy controls and that the high-selenium yeast supplementation helps prevent oxidative damage to DNA [Zachara 2011].
Mercury Toxicity and Selenium-enriched Yeast Supplements
In a study of Chinese individuals living in a region characterized by high exposure to mercury, an intervention with a selenium-enriched yeast product was associated with a significantly increased elimination of mercury and with reduced levels of biomarkers for oxidative stress [Li 2012].
Pregnancy and Selenium Supplements
In a series of studies of 230 first-time pregnant women in Great Britain, researchers investigated the effect of supplementation with 60 micrograms of a selenium-enriched yeast preparation or a placebo from the 12th week of pregnancy until birth. The data from these studies showed that the pregnant women with low selenium status had a significantly increased risk of developing preeclampsia and/or pregnancy-induced hypertension [Rayman 2015].
In another series of studies, researchers assigned 166 first-time pregnant women to take 100 micrograms of a selenium-enriched yeast preparation or a matching placebo daily from the first trimester of pregnancy until delivery. The researchers used the Edinburgh Postnatal Depression Scale to evaluate the symptoms of postpartum depression during the eight weeks after birth. The selenium supplementation was associated with a significant increase in mean serum selenium concentration at term, while serum selenium levels remained unchanged in the control group. The mean Edinburgh Postnatal Depression Scale score in the selenium group was significantly lower than that of the control group. The results of the study suggest that supplementation with selenium during pregnancy may be an effective approach to preventing postpartum depression [Mokhber 2011].
In one of the studies of the 166 first-time pregnant women, the researchers observed that the selenium supplement significantly reduced the incidence of premature (pre-labor) rupture of membranes [Tara 2010].
Researchers have used a patented selenium-enriched yeast preparation in many of the best randomized controlled trials of the effects of supplementation with selenium:
- Absorption and retention
- Antioxidant protection
- Cancer prevention
- Cardiovascular disease risk
- Kidney patients on dialysis
- Mercury detoxification
Alehagen U, Aaseth J, Alexander J, Johansson P. Still reduced cardiovascular mortality 12 years after supplementation with selenium and coenzyme Q10 for four years: A validation of previous 10-year follow-up results of a prospective randomized double-blind placebo-controlled trial in elderly. PLoS One. 2018 Apr 11;13(4):e0193120.
Bendahl L & Gammelgaard B. Separation of selenium compounds by CE-ICP-MS in dynamically coated capillaries applied to selenized yeast samples. J. Anal. At. Spectrom. 2004;19:143-148.
Bomer N, Grote Beverborg N, Hoes MF, Streng KW, Vermeer M, Dokter MM, IJmker J, Anker SD, Cleland JGF, Hillege HL, Lang CC, Ng LL, Samani NJ, Tromp J, van Veldhuisen DJ, Touw DJ, Voors AA, van der Meer P. Selenium and outcome in heart failure. Eur J Heart Fail. 2020 Aug;22(8):1415-1423.
Bügel S, Larsen EH, Steenberg LC, Moesgaard S. Selenium from a high Se yeast supplement is well absorbed and retained in humans. Metal Ions in Biology & Medicine. 2004;8:206-209.
Clark LC, Combs GF, Turnbull BW, Slate E, & Alberts D. The nutritional prevention of cancer with selenium 1983-1993: a randomized clinical trial. JAMA. 1996;276:1957-1963.
Hurst R, Armah CN, Dainty JR, Hart DJ, Teucher B, Goldson AJ, Broadley MR, Motley AK, Fairweather-Tait SJ. Establishing optimal selenium status: results of a randomized, double-blind, placebo-controlled trial. Am J Clin Nutr. 2010 Apr;91(4):923-31.
Li YF, Dong Z, Chen C, Li B, et al. Organic selenium supplementation increases mercury excretion and decreases oxidative damage. Environ Sci Technol. 2012;46(20):11313-8.
Lippman SM, Klein EA, Goodman PJ, Lucia MS, Thompson IM, Ford LG, Parnes HL, Minasian LM, Gaziano JM, Hartline JA. 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;301:39–51.
Mokhber N, Namjoo M, Tara F, Boskabadi H. Effect of supplementation with selenium on postpartum depression: a randomized double-blind placebo-controlled trial. J Maternal Fetal Neonatal Med. 2011;24:104-8.
Rayman MP, Blundell-Pound G, Pastor-Barriuso R, Guallar E, Steinbrenner H, Stranges S. A randomized trial of selenium supplementation and risk of type-2 diabetes, as assessed by plasma adiponectin. PLoS One. 2012;7(9):e45269.
Rayman MP, Bath SC, Westaway J, Williams P. Selenium status in U.K. pregnant women and its relationship with hypertensive conditions of pregnancy. Br J Nutr. 2015;113:249-58.
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.
Tara F, Rayman MP, Boskabadi H, Ghayour-Mobarhan M. Selenium supplementation and premature (pre-labour) rupture of membranes: a randomized double-blind placebo-controlled trial. J Obstet Gynecol. 2010;30: 30-4.
Zachara BA, Gromadzinska J, Palus J, Zbrog Z. The effect of selenium supplementation in the prevention of DNA damage in white blood cells of hemodialyzed patients: a pilot study. Biol Trace Elem Res. 2011;142:274-83.
The information presented in this review article is not intended as medical advice and should not be used as such.
31 August 2023