Scrutinizing the evidence for breast
cancer procedures and treatments
Supplement Strategies - Selenium



    The mineral, selenium, is a powerful antioxidant.  Additionally,
    research has found other mechanisms of action of interest to
    breast cancer patients.

    Linking Selenium Deficiency to Breast Cancer

  • In 80 breast cancer patients who had a mastectomy, their blood
    levels of selenium were lower than in healthy patients.  In the
    patients, there was a significantly higher concentration of selenium
    in cancerous tissue, as opposed to adjacent healthy tissue.  The
    higher concentration of selenium in cancerous tissue may be
    attributable in part to selenium's defense mechanism (selenium
    activates the antioxidant glutathione) against the carcinogenic
    process. (See Charalabopoulos K et al., Selenium in Serum and
    Neoplastic Tissue in Breast Cancer: Correlation with CEA, bjcancer

  • Selenium helps to convert T(4) - thyroxine, the prohormone with 4
    molecules of iodine into T(3) - triiodothyrone, the cellularly active
    thyroid hormone, with three molecules of iodine.  Thyroid hormones
    help the entire body - raising the metabolic rate and balancing
    physiological functions.

  • Selenium is an antioxidant, a part of glutathione peroxidase, which
    prevents fats from being oxidized.  During the production of thyroid
    hormones, selenium helps to degrade excess hydrogen peroxide
    that can damage the cells.

    Selenium Reverses Chromosome Breaks

    UPDATE:  Selenium has several anticancer properties, including
    protection against oxidation and enhancing nucleotide excision repair.

    Women who carry a mutation of the BRCA1  gene were found to have
    more chromosome breaks (which can lead to breast cancer)than women
    who did not carry the mutation.  When women with the BRCA1 mutation
    were given selenium for three months, the number of their chromosome
    breaks were reduced to normal.

    (See Kowalska E et al., Increased Rates of Chromosomes Breakage in
    BRCA1 Carriers are Normalized by Oral Selenium Supplementation,
    Cancer Epidemiology Biomarkers and Prevention 2005. See also
    Alternative Medicine Magazine, March 2006.)

    Double-Blind, Placebo-Controlled Cancer Study

    Although there have been many studies on selenium, we include it on the
    list of beneficial supplements for cancer principally because of the
    following double-blind, placebo-controlled study published in JAMA.

    Editor's note: the usual recommended selenium dose is
    200 mcg. Selenium works synergistically with iodine and Vitamin E.

    Selenium supplements can reduce cancer rates, new study shows

    Jan. 7, 1997 Press release

    ITHACA, N.Y. -- Men and women taking selenium supplements for 10
    years had 41 percent less total cancer than those taking a placebo, a new
    study by Cornell University and the University of Arizona shows. "Although
    more than a hundred of animal and dozens of epidemiological studies
    have linked high selenium status and cancer risk, this is the first double-
    blind, placebo-controlled cancer prevention study with humans that
    directly supports the thesis that a nutritional supplement of selenium, as a
    single agent, can reduce the risk of cancer," said Gerald F. Combs Jr., a
    nutritional biochemist and Cornell professor of nutritional sciences.

    Combs and a group of co-authors reported their findings in the Jan. 1,
    1997 issue of The Journal of the American Medical Association. The
    senior author is epidemiologist Larry Clark, who was at Cornell at the
    onset of the study and is now at the Department of Family and Community
    Medicine at the University of Arizona School of Medicine.

    In 1983, the researchers recruited 1,312 randomized patients with
    histories of skin cancer at seven dermatology clinics located in low-
    selenium areas of the United States (Augusta and Macon, Ga., Columbia,
    S.C., Wilson and Greenville, S.C., Miami, and Newington, Conn., where
    consumers ingest an average of about 100 micrograms of selenium a
    day). The patients were given either a placebo or a 200-microgram daily
    supplement of selenium (twice the average amount these Americans
    consume in their diet, thereby tripling their selenium intake).

    Skin cancer patients were chosen because they have a 25 percent
    annual chance of a recurrence, and skin cancer is easy to diagnose and
    can be quickly treated. The researchers set out to determine whether
    they could reduce the average recurrence rate with selenium

    Ironically, 10 years later, the results were not significant for skin cancer.
    However, they were "compelling" for overall cancer incidence and
    mortality rates, Combs stressed. Of the selenium group, 69 developed
    some type of cancer compared with 116 of the placebo group; 28 of the
    selenium patients died of cancer compared with 58 from the placebo

    "Overall, the selenium group experienced 18 percent less mortality than
    the placebo group, and almost all of that difference was due to some form
    of cancer," said Combs, who credits Cornell with having the longest
    history of research in selenium nutrition research in the world. "This is the
    first time anyone has shown that any single nutrient can result in such a
    reduction in cancer risk. The fact that we saw a pattern in lower incidence
    and mortality rates across all the clinics gives us even greater confidence
    in these findings."

    Prostate, esophageal, colorectal and lung cancer rates were among the
    most dramatic: patients in the selenium group had 71 percent, 67 percent,
    62 and 46 percent reductions in cancer rates, respectively, than the
    placebo group.

    Selenium blood levels vary widely in populations. Even Americans with the
    lowest selenium intake of 60 to 80 micrograms per day -- those living
    along the Southeastern seaboard and in the Pacific Northwest -- ingest
    two to five times more than citizens of New Zealand and 10 to 20 times
    more than people living in some areas of China. Selenium blood levels
    vary among populations largely because of wide differences in soil,
    agronomic practices, food availability and preferences and methods of
    food preparation.

    The University of Arizona-Cornell research team reported in 1991 that low
    selenium levels in the blood were linked to increased risk of neoplastic
    polyps in the colon, a precursor to colorectal cancer. And in other studies
    at Cornell, colleagues of Combs' reported in 1995 that animals fed diets
    high in selenium had 50 percent fewer tumors than those fed diets of
    average selenium content.

    Of the 40 nutrients currently recognized as essential for human nutrition,
    selenium was the last to be recognized in 1957. A key component for at
    least two essential enzymes, selenium provides the body with antioxidant
    protection in concert with vitamin E and is required for normal thyroid
    hormone metabolism.

    The study was funded in part by grants from the American Institute of
    Cancer Research, the American Cancer Society and the National
    Institutes of Health.

Breast Cancer ChoicesTM

    These statements have not been evaluated by the U.S. Food & Drug Administration.  
    The information discussed is not intended to diagnose, treat, cure, or prevent any disease.

    This website is intended as information only. The editors of this site are not medically-trained.
    Please consult your licensed health care practitioner before implementing any health strategy.

    The information provided on this site is designed to support, not replace, the relationship that
    exists between a patient/site visitor and his/her existing physician. This site accepts no
    advertising. The contents of this site are copyrighted 2004-2012 by Breast Cancer Choices,
    Inc., a 501 (c) (3) nonprofit organization run entirely by unpaid volunteers.
    Contact us with comments or for reprint permission at admin@breastcancerchoices.org

    Web page updated January 1, 2019

Selenium difficiency
proposed as a way of
detecting breast cancer risk

Breast Cancer Res Treat.
1990 Jul;16(1):57-61.

Selenium in serum as a
possible parameter for
assessment of breast disease.

Krsnjavi H, Beker D.

Institute for Medical Research
and Occupational Health,
Zagreb, Yugoslavia.

The level of selenium in blood
serum was determined in 33
patients with breast cancer, 13
women with verified
mastopathy, and 43 healthy
subjects from the Zagreb area.
In the second and third
quartiles the values of
selenium obtained from sick
subjects (41-58 micrograms/L)
and healthy subjects (73-89
micrograms/L) differed
significantly (P less than
0.001). In the group of subjects
with mastopathy, serum
selenium in the same way
ranged from 67-76
micrograms/L and did not differ
significantly from the group of
healthy women, but differed
significantly from the patients
with breast cancer (P less than

Such a result leads to the
conclusion that
determination of selenium
in the blood could be used
as a non-invasive
diagnostic parameter in
clinical assessment of
malignant breast disease.
How to take Selenium
Home    FAQ    Strategies    Discussion    Iodine   Hormones    Contact    Store