Two Recent Studies on Selenium and Cancer

Two Recent Studies on Selenium and Cancer




The Takeaway First

Taking in isolated nutrients might not only be useless, but it could increase your risk of disease, as several studies on selenium suggest. Avoid multi-vitamins that use the form of selenium selenomethionine or selenite alone, as this compound is probably ineffective and possibly harmful. It’s best to get the vitamins and minerals you need from natural sources that contain them. For extra selenium, eat Brazil nuts, fish, organ meats or  supplement from High Selenized Yeast.

The Details: Study #1 Prostate Cancer

The Health Professionals Follow-Up Study followed 4459 men who were initially diagnosed with non-metastatic prostate cancer. From 1988 to 2010 researchers examined whether selenium supplement use (from selenium-specific supplements and multivitamins) affected risk factors for disease or caused their prostate cancer to progress.

  • They found no statistically significant association between selenium supplement use and biochemical recurrence, cardiovascular disease mortality, or overall mortality. Despite this, there is evidence to suggest that taking more than 140 μg (that’s micrograms) of selenium per day after diagnosis of non-metastatic prostate cancer may increase risk of prostate cancer mortality.
  • Nine hundred sixty-five of the men in this study who had non-metastatic prostate cancer at diagnosis died before 2010. Of these deaths, 23.4% were because of prostate cancer, 27.7% because of CVD.       At diagnosis, the highest-dosage (≥140 μg/d) selenium supplement users did more vigorous physical activity, smoked less, used other supplements, and were more likely to have clinical T1 stage cancers; usage did not vary by biopsy Gleason score.
  • Compared with study participants who didn’t use selenium supplements, users had an increased risk of dying from prostate cancer.
  • There was some attenuation of the main estimates after adjustment for clinical factors; the addition of lifestyle factors and prediagnosis supplement use strengthened the association.
  • Compared with nonusers, men who took the highest doses of selenium after being diagnosed with prostate cancer had a 36% decreased risk of dying from heart disease, but that risk was not statistically significant. (Kenfield et al. 2014)

Study Details #2 Colon Cancer

This next study was part of the European Prospective Investigation on Cancer. Approximately 95% of the EPIC subjects had serum Se levels below <124 µg/L (and approximately 80% were below 100 µg/L), and the correlation between Se and SePP (hepatic selenoprotein P) levels was relatively high (r = 0.60; p  = <0.001), indicating that most subjects were sub-optimal in Se when judged by previously published data on Se levels required for full expression of SePP and other selenoproteins as the criterion for Se sufficiency. Why is this so important? It means that most of the cancer patients in the EPIC study had low selenium levels, which, in other words, means that low selenium and cancer were associated. (Hughes et al. 2014)

This study gives preliminary evidence that doses of selenium may have a protective effect against colorectal cancer in in populations that tend to have lower levels of selenium, such as females or people in Western Europe. While I stress there was no causal relationship found in this study, the results are compelling and match the outcome of the NPC trial showing a %46 reduction in colorectal cancer in subject consuming selenized enriched-yeast.

My Take On This

Selenium (Se) is a trace mineral found in food, primarily fish, meats, and whole grains. The largest concentration of selenium is found in Brazil nuts and offal. (Do you know what offal is? It’s organ meat.) Much of the Se content in foods is lost through processing and cooking. The refining of grains reduces Se content by 50–75 percent, boiling reduces it by almost half.

Besides selenium’s well known benefits for fertility and thyroid function, research over the last twenty years has looked into its anti-cancer effects. Before I continue, let’s talk about the different types of selenium:

In food, you have 4 types of Selenium: selenocysteine (Secys), selenomethionine (SeMet, and this is the organic form), selenite, and selenate (these last two are the inorganic forms). Selenocysteine (Secys) and selenomethionine is mostly found in food and its most absorbable.

Selenium shows up in most multi-vitamins as selenite and selenomethionine. Interestingly, the selenium that is found in foods like Brazil nuts, mustard seeds, and fresh produce grown in selenium-rich soil is not the same as these.

Investigating each of these three forms of selenium has produced intriguing findings. Laboratory studies reveal the reason: each form of selenium has a unique beneficial method of working, and each affects different cancer types somewhat differently. The human body handles each form of selenium in a different fashion, and each form contributes uniquely to preventing cancer from emerging.

This research and my years of success in treating illness with holistic medicine tells me that by combining all three forms of selenium (selenomethionine, selenocysteine and methyl-selenocystine), you can achieve a greater reduction in cancer risk than by taking any of them alone. This way, you can take advantage of all of the mechanisms by which selenium compounds work against cancer.

The primary reason that vitamin manufacturers prefer sodium selenite/selenate over safer, more beneficial forms like chelated or yeast-grown selenium is because it is more profitable to use raw materials of lower quality.

Why do I Prefer High-Selenized Yeast?

I prefer High-Selenium Yeast because its superior benefits are documented with good science. Waters et al. (2003) found that high-selenium yeast was more effective than selenomethionine in reducing DNA damage and increasing epithelial cell apoptosis (natural cell death) within aging canine prostate cells. Another study published in the reputable journal JAMA found that men who received supplemental selenium in the form of 200 mcg/day of high-selenium yeast had a 63% reduced incidence of prostate, 58 % colon, rectal and 43% lung cancer over a period of about 4.5 years, as compared to placebo (Clark et al., 1996).

In these studies, men who had the lowest selenium levels to begin with experienced the greatest effects. Duffield-Lillico et al. (2003), for example, observed that subjects who had the lowest plasma selenium before the study began had the highest rates of cancer after the study. This strongly suggests that selenium has a protective effect.

For the first time, researchers examined the effects of Selenomethionine (SeMet) and Selenized Yeast (HSY) on prostate cancer relevant biomarkers in healthy men. This was a randomized, double-blind, placebo-controlled trial that compared high-selenized yeast (200 or 285 mcg/day) to SeMet (200 mcg/day) administered for 9 months in 69 men. Researchers looked at blood levels of selenium-containing compounds and biomarkers for oxidative stress (free radicals). Secondly, they looked for blood glucose and PSA levels. They found that biomarkers of oxidative stress were reduced following supplementation with HSY but not SeMet, which to me means that HSY is probably better. (Richie et al. 2014)

Dr. David McCormick at the Experimental Toxicology and Carcinogenesis Division, IIT Research Institute in Chicago found that SeMet or vitamin E supplementation had no effect on the prevention of prostate cancer in rats. Only selenized yeast provided the only potential evidence of chemopreventive activity against prostate cancer that was found in the four studies. (McCormick & Rao., 2010 ).

A recent report, the SELECT study, showed a significant increase of advanced prostate cancer in men consuming 200mcg/day of SeMet (Kristal et al. 2014).

Why does High-Selenized Yeast work better than Selenomethionine alone? Because HSY has more than one kind of selenium, and these different components work together. While SeMet is just one compound, HSY contains SeMet plus selenocysteine and methylselenocysteine, which very likely work in concert to achieve a greater effect. From experience I know that taking isolated nutrients does not work best and can even be outright dangerous.

The Bottom Line

Avoid multivitamins that use isolated forms of selenium such as selenomethionine or selenite. Not only may they be only marginally beneficial, but they may actually increase cancer risk. When including selenium in your dietary regimen choose High Selenized Yeast (also known as Selenized enriched-yeast).



Cypress – SelenoExcell


Kenfield SA, Van Blarigan EL, DuPre N, Stampfer MJ, L Giovannucci E, Chan JM. Selenium Supplementation and Prostate Cancer Mortality. J Natl Cancer Inst. 2014 Dec 12;107(1).

Combs, G.F., Jr.; Gray, W.P. Chemopreventive agents: Selenium. Pharmacol. Ther. 1998, 79, 179–192.

Clark LC, et al. 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;276(24):1957–63.

Clark LC, et al. Decreased incidence of prostate cancer with selenium supplementation: results of a double-blind cancer prevention trial. Br J Urol. 1998;81(5):730–4.

Hughes DJ, et al..]Selenium status is associated with colorectal cancer risk in the European prospective investigation of cancer and nutrition cohort. Int J Cancer. 2015 Mar 1;136(5):1149-61.

Kristal AR, Darke AK, Morris JS, et al. Baseline Selenium Status and Effects of Selenium and Vitamin E Supplementation on Prostate Cancer Risk. J Natl Cancer Inst. 2014;106(3):djt456

McCormick, D. L., Rao, K. V., Johnson, W. D., Bosland, M. C., Lubet, R. A., & Steele, V. E. (2010). Null activity of selenium and vitamin e as cancer chemopreventive agents in the rat prostate. Cancer Prev Res (Phila), 3(3), 381-392. doi: 10.1158/1940-6207.capr-09-0176

Waters DJ, Shen S, Kengeri SS, et al. Prostatic response to supranutritional selenium supplementation:comparison of the target tissue potency of selenomethionine vs. selenium-yeast on markers of prostatic homeostasis. Nutrients 2012; 4(11):1650-63.

Richie JP Jr, et al.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.


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