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Selenium’s Impact on Cancer Reduction

January 2017

By Sarah Lewis

Selenium is a trace mineral critical for human life.

While there are many different forms of selenium, not all of them provide the same health benefits. This article presents data on the unique benefits of selenium-enriched yeast.

While selenium can be found in foods such as Brazil nuts, pinto beans, and beef, the amount of selenium that is obtained from our diet is highly uneven. This is because the amount of natural selenium in the soil fluctuates from region to region.

Many areas of the United States such as Texas, the Southwest, lower Southeast and Northwestern mountain states have selenium deficient soil. Therefore foods grown in these regions will not be rich in selenium.1

In the past year, two new studies reveal that selenium status is suboptimal in many people in the industrialized world, and that low selenium status raises the risk for colorectal cancers and cancers of the liver and gallbladder.2,3

Ample selenium has been shown to be a relevant factor in protecting against a uniquely male malignancy, prostate cancer.4-9

But men aren’t the only ones at increased cancer risk when their selenium levels drop, and prostate cancer is far from the only cancer affected by poor selenium status.

Back in 1983, a group of researchers began a human study to examine the effects of selenium-enriched yeast on skin cancer.

The researchers found that subjects supplementing with this yeast-based selenium had an approximately 46%-63% reduction in the risk of colorectal, lung, and prostate cancers, with a 50% reduction in the risk of mortality for all cancers. The results were later published in the Journal of the American Medical Association7 and made headline news stories around the world. This generated intense interest in the scientific community in the protective power of selenium.

Recent studies amplify the importance of maintaining satisfactory selenium levels and their impact on cancer risk reduction.
What You Need to Know
Selenium

Selenium

  • Selenium is a trace element and co-factor for more than 25 key enzymes that can’t function without it.
  • Most of those enzymes are involved in systems that protect cells and their DNA from oxidative stress that, unopposed, leads to cancer.
  • Studies show that those with lower selenium blood levels are at substantially increased risk for cancers in a variety of organs.
  • Selenium supplementation, on the other hand, has been shown effective at reducing cancer incidence and producing protective biochemical shifts that shield cells and DNA from damage.
  • No single selenium form, however, provides all of the cancer-preventing benefits available from selenium.
  • Instead, a thoughtful regimen that includes multiple forms of selenium is most likely to offer comprehensive cancer- prevention properties.

Selenium Lowers Cancer Risk

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The association between inadequate selenium status and the risk for many different cancers naturally leads to the question, “Can supplemental selenium reduce cancer risk?

The answer is that optimal selenium levels through supplementation provide a protective function against the risk of cancer.

Studies going back to the 1970s have generally supported supplemental selenium as a cancer risk-reducing intervention.

As mentioned near the beginning of this article, a randomized, controlled trial published in 1996 demonstrated that 200 mcg of selenium daily from selenium-rich yeast was associated with a 50% reduction in the risk of dying from cancer, a 37% reduction in the risk of developing cancer, and reductions of 58%, 63%, and 46% in the risks for developing colorectal, prostate, and lung cancers, respectively.7

Deeper analysis showed that, among men with baseline normal levels of prostate-specific antigen, or PSA, a marker of cancer risk, those in the treated group showed an overall 74% reduction in their risks of prostate cancer.8

Colon cancer is a selenium-responsive malignancy, as shown in a placebo-controlled 2013 study that supplemented active subjects with 200 mcg of selenium, along with zinc and vitamins A, C, and E over a 5-year period.10

These study subjects consisted of 411 people with polyps removed during screening colonoscopy, indicating their higher risk for colorectal cancers.

In the supplemented group, 38 had a recurrence of polyps, while 62 recurred in the placebo group.

This worked out to a 39% reduction in the risk of recurrence in those who supplemented with selenium and vitamins, compared with un-supplemented placebo recipients.

A 2015 study shows that cervical cancer may also be preventable with selenium supplementation.11

In this study, 56 women diagnosed at biopsy with cervical intraepithelial neoplasia (precancerous lesions) were randomly assigned to receive 200 mcg of selenium from yeast or a placebo, daily for 6 months.

The findings showed that 88% of supplemented women had regression of their precancerous lesions, compared with only 56% in the placebo group. This significant difference was accompanied by decreases in fasting blood sugar, insulin, and insulin resistance, all factors associated with increased cancer and metabolic risks.

Some insight into how selenium supplementation works to reduce cancer comes from a study of blood cells from hemodialysis patients, who are at known increased risk for DNA damage, the precursor of new cancers.12

Forty-two dialysis patients randomly received either selenium-rich yeast or a placebo of standard yeast for 3 months.

The dialysis patients had significantly lower selenium levels than did healthy controls, as expected, but these rose significantly with supplementation.

Markers of DNA damage in circulating white blood cells (a good indicator of damage throughout the body) were three times higher in dialysis patients than in controls at the outset. After 3 months of selenium supplementation, DNA damage markers fell in the dialysis patients, to levels 16% lower than those in healthy controls.

No similar changes were seen in the placebo recipients.

Not All Selenium is the Same

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There are several different forms of selenium and not all of them offer the same health benefits. For example, in a very large and well-publicized 2009 study, researchers from the Selenium and Vitamin E Cancer Prevention Trial (SELECT) reported that, after treating more than 35,000 men with one form of selenium (L-selenomethionine) alone (200 mcg), selenium plus vitamin E, or placebo, they found no significant differences in participants’ risk for prostate cancer in any of the groups compared with placebo.13

Because this was such a large study, it garnered an outsized share of attention, and many scientists and other readers came away with the impression that selenium has no role in cancer prevention.

It should be noted that multiple scientific studies dating back to the 1970s show that different forms of selenium provide a spectrum of protection against cancer. Life Extension® long ago discussed the importance of including more than one form of selenium in one’s daily supplement program.

Selenium in a variety of forms has been shown to produce significant reductions in cancer risks.

One form of selenium that has received relatively little attention is selenium-enriched yeast, obtained from high-selenium brewer’s yeast.

The study discussed near the beginning of this article, which involved 1,312 patients over a total of 8,271 person-years, found that daily supplementation with selenium-enriched yeast (200 mcg/day), had a 50% reduced risk of dying from cancer, and a 37% decreased risk of developing cancer, compared with placebo recipients.7

Further, with regard to specific cancers, the study found reductions of 46%, 58%, and 63% in the risks of lung, colorectal, and prostate cancers, respectively.7

Selenium in its different forms has demonstrated cancer-preventive effects.
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Selenium Status and Cancer Risks

As of this writing, selenium status has been significantly associated with lower cancer incidence, as shown in the following table:

Type of Cancer

Impact of Selenium Status

Bladder18

39% reduction with higher selenium levels

Lung19

90% reduction with higher selenium levels

Larynx (throat)19

77% lower with higher selenium levels

Prostate4

71% reduction with higher selenium levels

Head-and-Neck21

45% reduction with higher selenium levels

Lung20

140% higher with low selenoprotein levels

Different Forms of Selenium

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The different forms of selenium have been shown to provide various protective properties against cancer, oxidative stress, DNA damage and even shielding against toxic metal poisoning. For this reason, it is recommended that it is best to ingest a 200 mcg “cocktail” daily of various selenium forms to provide broad- spectrum coverage against the diseases of aging.14,15

Here are brief descriptions of well-studied forms, highlighting how each can contribute to selenium-based protection against cancer.

  • Sodium selenite is a simple chemical salt of sodium and selenium. This form of selenium has the ability to ramp up our natural immune system to find and destroy tumor cells.16,17
  • Selenium-methyl L-selenocysteine triggers cancer cell suicide (apoptosis) and also acts on more advanced cancer cells that have lost the fundamental “suicide gene.”14
  • Selenium from yeast provides advanced protection against oxidative stress and resulting DNA damage, to reduce the risks that a cell will undergo transformation into a malignancy.6

Because optimum cancer prevention requires protection from DNA damage, enhanced self-destruction of malignant cells, and a boosted immune system, the benefits of using multiple forms of selenium are obvious.

Summary

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Preventing cancer requires a multifactorial approach.

One mechanism involved in cancer development is oxidative stress and the DNA damage that it causes.

Selenium is a natural element capable of fighting oxidative stress and has been shown to be effective in preventing cancer and the biochemical changes that precede it.

But because one large study found no significant effects on prostate cancer risks using just one form of selenium (L-selenomethionine), many have turned away from this valuable mineral.

The fact is that selenium in its different forms has demonstrated strong cancer-preventive effects.

Recent studies amplify the importance of maintaining satisfactory selenium levels.

Don’t be fooled by spurious science, often based on flawed studies. Selenium-enriched yeast supplements have demonstrated strong potential for reducing cancer risk. Other forms of selenium contribute to enhanced immunological destruction of early cancers, trigger cancer cell “suicide,” and protect tissues from oxidative stress.

Overall, the evidence points to a daily selenium dose of 200 mcg to reduce cancer risk, which should ideally utilize multiple forms to obtain comprehensive protection.

No single nutrient should be relied on to protect against cancer. This magazine consistently reminds readers of dietary and lifestyle factors that play huge roles in one’s risk of developing malignant disease.

If you have any questions on the scientific content of this article, please call a Life Extension® Wellness Specialist at 1-866-864-3027.

References

  1. Available at: http://mrdata.usgs.gov/geochem/doc/averages/se/usa.html. Accessed 31 October, 2016.
  2. Hughes DJ, Duarte-Salles T, Hybsier S, et al. Prediagnostic selenium status and hepatobiliary cancer risk in the European Prospective Investigation into Cancer and Nutrition cohort. Am J Clin Nutr. 2016;104(2):406-14.
  3. Hughes DJ, Fedirko V, Jenab M, et al. Selenium status is associated with colorectal cancer risk in the European prospective investigation of cancer and nutrition cohort. Int J Cancer. 2015;136(5):1149-61.
  4. Allen NE, Travis RC, Appleby PN, et al. Selenium and Prostate Cancer: Analysis of Individual Participant Data From Fifteen Prospective Studies. J Natl Cancer Inst. 2016;108(11).
  5. Outzen M, Tjonneland A, Larsen EH, et al. Selenium status and risk of prostate cancer in a Danish population. Br J Nutr. 2016;115(9):1669-77.
  6. Richie JP, Jr., Das A, Calcagnotto AM, 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;7(8):796-804.
  7. Clark LC, Combs GF, Jr., Turnbull BW, 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.
  8. Clark LC, Dalkin B, Krongrad A, 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.
  9. El-Bayoumy K, Richie JP, Jr., Boyiri T, et al. Influence of selenium-enriched yeast supplementation on biomarkers of oxidative damage and hormone status in healthy adult males: a clinical pilot study. Cancer Epidemiol Biomarkers Prev. 2002;11(11):1459-65.
  10. Bonelli L, Puntoni M, Gatteschi B, et al. Antioxidant supplement and long-term reduction of recurrent adenomas of the large bowel. A double-blind randomized trial. J Gastroenterol. 2013;48(6):698-705.
  11. Karamali M, Nourgostar S, Zamani A, et al. The favourable effects of long-term selenium supplementation on regression of cervical tissues and metabolic profiles of patients with cervical intraepithelial neoplasia: a randomised, double-blind, placebo-controlled trial. Br J Nutr. 2015;114(12):2039-45.
  12. Zachara BA, Gromadzinska J, Palus J, et al. 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(3):274-83.
  13. 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.
  14. Suzuki M, Endo M, Shinohara F, et al. Differential apoptotic response of human cancer cells to organoselenium compounds. Cancer Chemother Pharmacol. 2010;66(3):475-84.
  15. Lunoe K, Gabel-Jensen C, Sturup S, et al. Investigation of the selenium metabolism in cancer cell lines. Metallomics. 2011;3(2):162-8.
  16. Kiremidjian-Schumacher L, Roy M, Glickman R, et al. Selenium and immunocompetence in patients with head and neck cancer. Biol Trace Elem Res. 2000;73(2):97-111.
  17. Asfour IA, El Shazly S, Fayek MH, et al. Effect of high-dose sodium selenite therapy on polymorphonuclear leukocyte apoptosis in non-Hodgkin’s lymphoma patients. Biol Trace Elem Res. 2006;110(1):19-32.
  18. Amaral AF, Cantor KP, Silverman DT, et al. Selenium and bladder cancer risk: a meta-analysis. Cancer Epidemiol Biomarkers Prev. 2010;19(9):2407-15.
  19. Jaworska K, Gupta S, Durda K, et al. A low selenium level is associated with lung and laryngeal cancers. PLoS One. 2013;8(3):e59051.
  20. Epplein M, Burk RF, Cai Q, et al. A prospective study of plasma Selenoprotein P and lung cancer risk among low-income adults. Cancer Epidemiol Biomarkers Prev. 2014;23(7):1238-44.
  21. Maasland DH, Schouten LJ, Kremer B, et al. Toenail selenium status and risk of subtypes of head-neck cancer: The Netherlands Cohort Study. Eur J Cancer. 2016;60:83-92.