The evidence from clinical studies shows that high-selenium yeast preparations give the best health outcomes [Alehagen; Blot; Clark; Yu].
Today, I want to look at the documented properties of the high-selenium yeast preparation that was developed for use in the PRECISE studies. PRECISE is the acronym for PREvention of Cancer by Intervention with SElenium. The PRECISE studies were designed to test the effectiveness of selenium supplementation at preventing cancer.
The preparation is also the high-selenium yeast preparation used in the KiSel-10 study of combined selenium and Coenzyme Q10 supplementation of healthy elderly citizens to protect against heart disease. Professor Urban Alehagen and the researchers at Linköping University in Sweden have written about the special interrelationship between selenium and Coenzyme Q10: our cells need adequate selenium status to obtain optimal concentrations of Coenzyme Q10, and our cells need adequate Coenzyme Q10 status to realize optimal selenoprotein function [Alehagen].
A high-selenium yeast preparation must have scientific documentation for the following properties:
- stability
- absorption and bio-availability
- efficacy
- safety
Stability
The effective high-selenium yeast preparation contains approximately 60% natural (not synthetic) l-selenomethionine and as many as 30 other species of selenium including gamma-glutamyl-Se-methylselenocysteine. Methylselenocysteine is thought to be an important component of an effective high-selenium yeast preparation. Speciation studies have shown that high-selenium yeast preparation contains less than one percent inorganic selenium [Larsen].
What are we talking about here? There are different forms of selenium – both inorganic and organic — that a manufacturer of a selenium supplement can use. The results from randomized controlled studies show that organic high-selenium yeast preparations confer more health benefits than inorganic selenium preparations do [Alehagen; Clark; Blot; Yu].
In addition, high-selenium yeast preparations containing organic l-selenomethionine have been associated with better health outcomes than selenium preparations with a synthetic l-selenomethionine have. Compare, for example, the results of the Nutritional Prevention of Cancer study with the results of the SELECT study [Clark; Lippman].
The important thing for us consumers is that we can count on getting a stable, standardized pharmaceutical-grade selenium preparation that has the same proportions of species of selenium in batch after batch.
Absorption and bio-availability
In the same way, it is important to us to purchase a high-selenium yeast tablet that has a high absorbability, e.g. somewhere between 80% and 90%, consistently.
Depending on the region we live in, we may need a daily supplement of 50 micrograms, 100 micrograms, or 200 micrograms. It is possible to have our plasma or serum selenium concentrations tested. Scientific interpretation of clinical study outcomes suggests that the effective plasma selenium range for cancer prevention is between 120 micrograms per liter and 170 micrograms per liter [Hurst 2012].
The manufacturer of an effective high-selenium yeast preparation has documented evidence that a daily supplement of 100 micrograms will increase an individual’s plasma selenium concentration by more than 50% after a few months of steady supplementation, all depending, of course, upon the baseline plasma selenium status of the individual [Larsen].
Efficacy of high-selenium yeast in disease prevention
Arguably, the two biggest health benefits of selenium supplementation – upon raising selenium status to effective levels – are prevention of cancer and enhancement of thyroid function.
I have posted several articles about selenium and cancer risk on this web-site. I will be summarizing the bio-medical literature about selenium and thyroid function in a future article.
In the remainder of this article, I would like to review some other health outcomes associated with a pharmaceutical-grade high-selenium yeast preparation.
High-selenium yeast and pregnancy
Reduced oxidative stress: The levels of bio-markers of oxidative stress increase significantly during pregnancy. Understandably. Supplementation of first trimester pregnant women with 100 micrograms per day for six months kept the levels of pregnancy-related oxidative stress bio-markers unchanged. In the placebo group, the same pregnancy-related oxidative stress bio-markers increased by 32%. The selenium supplementation had a protective effect [Tara 2010].
Less post-partum depression: Supplementing first trimester pregnant women with 100 micrograms per day until delivery was associated with significantly reduced incidence of post-partum depression [Mokhber 2011].
Reduced risk of pre-eclampsia: Daily supplementation of pregnant women with 60 micrograms of high-selenium yeast from week 12-14 until delivery was associated with lower concentrations of SFlt-1 proteins, which are bio-markers for the risk of pre-eclampsia. The supplementation with 60 micrograms daily was also associated with higher maternal levels of Selenoprotein P, which are normally reduced during pregnancy because of the transfer of selenium to the fetus [Rayman 2014].
Reduced risk of pre-labor rupture of membranes: The incidence of pre-labor rupture of membranes in first-time-pregnant women who were supplemented with 100 micrograms of high-selenium yeast daily was significantly lower than the incidence in the placebo group [Tara 2010].
High-selenium yeast and mercury excretion
Daily supplementation with 100 micrograms of high-selenium yeast for 90 days was associated with sharply increased mercury excretion in study participants with long-term exposure to mercury [Li 2012].
High-selenium yeast and improved immune system function
Researchers supplemented study participants with 0, 50, 100, or 200 micrograms of high-selenium yeast daily for 12 weeks. They administered an influenza vaccine to the study participants. There was a dose-dependent up-regulation of the immune system response to the vaccine [Goldson 2011].
High-selenium yeast and cholesterol levels
A study of elderly British study participants supplemented with 0, 100, 200, or 300 micrograms of high-selenium yeast for six months showed modestly beneficial outcomes in the total cholesterol-HDL good cholesterol ratios. The ratios of total cholesterol to good cholesterol decreased in response to increasing high-selenium yeast dosages [Rayman 2011]. Put another way, good cholesterol was a higher percentage of the total cholesterol in the study participants taking higher dosages of high-selenium yeast.
A study of elderly Danish study participants supplemented with 0, 100, 200, or 300 micrograms of high-selenium yeast for five years showed the same trend towards improved cholesterol ratios with increasing dosages of high-selenium yeast [Cold 2015]. These results stopped short of statistical significance; however, the improvements in good cholesterol may have clinical significance.
High-selenium yeast and heart disease
In the KiSel-10 study, combined supplementation with high-selenium yeast and Coenzyme Q10 was associated with significantly reduced risk of death from heart disease [Alehagen].
High-selenium yeast and chronic kidney disease
At baseline, patients with chronic kidney disease had DNA damage in white blood cells three times the level of healthy individuals. Daily supplementation of the chronic kidney disease patients with 200 micrograms for three months was associated with a significant decrease in DNA damage in white blood cells, down to a level that was 16% lower than the levels of DNA damage in healthy individuals [Zachara 2011].
Safety of high-selenium yeast
No serious adverse effects:
A review of the results of 47 studies with a pharmaceutical-grade high-selenium yeast preparation has shown no reports of serious adverse effects and no alterations in the study participants’ toxicity parameters [Sindberg 2016].
No muscle tissue build-up:
Long-term supplementation for several years with dosages ranging from 62.5 to 262.5 micrograms resulted in a selenium steady state in muscle tissue. There was no continuous build-up and no danger of toxic build-up in muscle tissue. Moreover, there was a significant positive correlation between muscle tissue selenium levels and selenium concentrations in plasma, whole blood, red blood cells, head hair, and toe nails [Behne 2010].
High-selenium yeast and diabetes:
Daily supplementation of elderly study participants with low selenium status with 100, 200, and 300 micrograms for six months had no effect on adiponectin levels thus reassuring researchers that selenium supplementation did not show a diabetic effect in a sample of elderly individuals with relatively low selenium status [Rayman 2012].
High-selenium yeast and pregnancy:
Daily supplementation with 100 micrograms of high-selenium yeast from the first trimester until delivery seems to be safe in pregnancy and is quite possibly much needed [Tara 2010; Mokhber 2011; Rayman 2014].
Conclusion
In the body, the selenium from supplements is incorporated into selenoproteins that have a number of beneficial health effects:
- antioxidant effects
- anti-inflammatory effects
- anti-viral effects
It is important to choose a high-selenium yeast preparation with documented stability, absorption, efficacy, and safety.
Sources
Alehagen, U., Johansson, P., Björnstedt, M., Rosén, A., & Dahlström, U. (2013). Cardiovascular mortality and N-terminal-proBNP reduced after combined selenium and Coenzyme Q10 supplementation: a 5-year prospective randomized double-blind placebo-controlled trial among elderly Swedish citizens. International Journal of Cardiology, 167(5), 1860-1866. doi:10.1016/j.ijcard.2012.04.156
Behne, D., Alber, D., & Kyriakopoulos, A. (2010). Long-term selenium supplementation of humans: selenium status and relationships between selenium concentrations in skeletal muscle and indicator materials. Journal of Trace Elements in Medicine and Biology, 24(2), 99-105. doi:10.1016/j.jtemb.2009.12.001
Blot, W. J., Li, J. Y., Taylor, P. R., Guo, W., Dawsey, S., Wang, G. Q., & Li, B. (1993). Nutrition intervention trials in Linxian, China: supplementation with specific vitamin/mineral combinations, cancer incidence, and disease-specific mortality in the general population. Journal of The National Cancer Institute, 85(18), 1483- 1492.
Clark, L. C., Combs, G. J., Turnbull, B. W., Slate, E. H., Chalker, D. K., Chow, J., & … Taylor, J. R. (1996). 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, 276(24), 1957-1963.
Cold, S., Winther, K. H., Pastor-Barriuso, R., & Rayman, M. P. (2015). Randomised controlled trial of the effect of long-term selenium supplementation on plasma cholesterol. British Journal of Nutrition, 114(11): 1807-18.
Goldson, A. J., Fairweather-Tait, S. J., Armah, C. N., Bao, Y., Broadley, M. R., Dainty, J. R., & … Hurst, R. (2011). Effects of selenium supplementation on selenoprotein gene expression and response to influenza vaccine challenge: a randomised controlled trial. Plos One, 6(3), e14771. doi:10.1371/journal.pone.0014771
Hurst, R., Hooper, L., Norat, T., Lau, R., Aune, D., Greenwood, D. C., & Fairweather-Tait, S. J. (2012). Selenium and prostate cancer: systematic review and meta-analysis. The American Journal of Clinical Nutrition, 96(1), 111-122.
Larsen, E. H., Hansen, M., Paulin, H., Moesgaard, S., Reid, M., & Rayman, M. (2004). Speciation and bioavailability of selenium in yeast-based intervention agents used in cancer chemoprevention studies. Journal of AOAC International, 87(1), 225-232. Efficacy of a high-selenium yeast preparation
Li, Y., Dong, Z., Chen, C., Li, B., Gao, Y., Qu, L., & … Chai, Z. (2012). Organic selenium supplementation increases mercury excretion and decreases oxidative damage in long-term mercury-exposed residents from Wanshan, China. Environmental Science & Technology, 46(20), 11313-11318. doi:10.1021/es302241v
Lippman, S. M., Klein, E. A., Goodman, P. J., Lucia, M. S., Thompson, I. M., Ford, L. G., & Coltman, C. J. (2009). Effect of selenium and vitamin E on risk of prostate cancer and other cancers: The Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA, 301(1), 39-51.
Mokhber, N., Namjoo, M., Tara, F., Boskabadi, H., Rayman, M. P., Ghayour-Mobarhan, M., & … Ferns, G. (2011). Effect of supplementation with selenium on postpartum depression: a randomized double-blind placebo-controlled trial. The Journal of Maternal-Fetal & Neonatal Medicine, 24(1), 104-108. doi:10.3109/14767058.2010.482598
Rayman, M. P., Searle, E., Kelly, L., Johnsen, S., Bodman-Smith, K., Bath, S. C., & … Redman, C. G. (2014). Effect of selenium on markers of risk of pre-eclampsia in UK pregnant women: a randomised, controlled pilot trial. The British Journal of Nutrition, 112(1), 99-111. doi:10.1017/S0007114514000531
Rayman, M. P., Stranges, S., Griffin, B. A., Pastor-Barriuso, R., & Guallar, E. (2011). Effect of supplementation with high-selenium yeast on plasma lipids: a randomized trial. Annals of Internal Medicine, 154(10), 656-665. doi:10.7326/0003-4819-154-10-201105170-00005
Rayman, M. P., Blundell-Pound, G., Pastor-Barriuso, R., Guallar, E., Steinbrenner, H., Stranges, S., & Guoying, W. (2012). A Randomized Trial of Selenium Supplementation and Risk of Type-2 Diabetes, as Assessed by Plasma Adiponectin. Plos ONE, 7(9), 1-9. doi:10.1371/journal.pone.0045269
Sindberg, C. D. (2016). Aspects of SelenoPrecise® documentation: A scientific summary of SelenoPrecise® absorption, speciation, effects in human material, and bio-marker measurements. Pharma Nord Research Library. Unpublished document.
Tara, F., Rayman, M. P., Boskabadi, H., Ghayour-Mobarhan, M., Sahebkar, A., Alamdari, D. H., & … Ferns, G. (2010). Prooxidant-antioxidant balance in pregnancy: a randomized double-blind placebo-controlled trial of selenium supplementation. Journal of Perinatal Medicine, 38(5), 473-478. doi:10.1515/JPM.2010.068
Tara, F., Rayman, M. P., Boskabadi, H., Ghayour-Mobarhan, M., Sahebkar, A., Yazarlu, O., & … Ferns, G. (2010). Selenium supplementation and premature (pre-labour) rupture of membranes: A randomised double-blind placebo-controlled trial. Journal of Obstetrics & Gynaecology, 30(1), 30-34. doi:10.3109/01443610903267507
Yu, S. Y., Zhu, Y. J., & Li, W. G. (1997). Protective role of selenium against hepatitis B virus and primary liver cancer in Qidong. Biological Trace Element Research, 56(1), 117-124.
Zachara, B. A., Gromadzinska, J., Palus, J., Zbrog, Z., Swiech, R., Twardowska, E., & Wasowicz, W. (2011). The effect of selenium supplementation in the prevention of DNA damage in white blood cells of hemodialyzed patients: a pilot study. Biological Trace Element Research, 142(3), 274-283. doi:10.1007/s12011-010-8776-0
The information presented in this review article is not intended as medical advice and should not be used as such.
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