Research on the Mineral Selenium
The following research abstracts
are presented to reflect the findings of possible benefits from
minerals as a dietary supplement and nutritional supplement.
You will find more on the ionic
selenium page.
Am J Clin Nutr. 1995 Dec. 62(6
Suppl). P 1477S-1482S
The people of Linxian County,
China have one of the world's highest rates of esophageal cancer.
Two intervention trials were conducted to determine whether
supplementation with specific vitamins and minerals could lower
mortality from or incidence of cancer in this population and
whether supplementation with multiple vitamins and minerals
would reduce esophageal and gastric cardia cancer in persons
with esophageal dysplasia. About 30,000 general population (GP)
subjects in the GP trial were randomly assigned to one of eight
intervention groups according to a one-half replicate of a 2(4)
factorial experimental design and were supplemented for 5.25
y with four combinations of micronutrients at doses from one
to two times the US recommended dietary allowance (RDA). About
3000 subjects in whom dysplasia was diagnosed in the dysplasia
trial were randomly assigned to groups receiving daily supplementation
with 14 vitamins and 12 minerals at two to three times the US
RDA or placebo for 6 y. Results of the dysplasia trial indicate
that in individuals with esophageal dysplasia, micronutrient
supplementation had little effect on T lymphocyte responses.
In contrast, male participants in the GP trial who were supplemented
with beta-carotene, vitamin E, and selenium
showed significantly (P <0.05) higher mitogenic responsiveness
of T lymphocytes in vitro than those not receiving these micronutrients.
CANCER RES. (USA) , 1994, 54/7
SUPPL. (1957s-1959s)
This presentation focuses on
research that could theoretically be applied to implement the
strategy of general population chemoprevention. The concept
is based on the premise of enhancing foods with known anticarcinogens
through either agricultural methods or food-processing technologies.
Two areas of our work are described: (a) garlic cultivated with
selenium fertilization and (b)
foods high in conjugated linoleic acid. Both selenium
and conjugated linoleic acid are powerful chemopreventive agents
in the animal tumor model. The rationale of delivering these
two specific compounds through the food system will be developed.
Preliminary studies will be su carcinogen-induced mammary cancer
in rats. Finally, the advantages of using foods to provide anticarcinogens
to the general population as part of a chemopreventive strategy
will also be discussed.
Carcinogenesis (United Kingdom)
, 1996, 17/9 (1979-1982)
Previous work has shown that
the efficacy of cancer prevention by selenium-enriched
garlic (Se-garlic) is primarily dependent on the action of selenium.
Additionally, supplementation of Se-garlic inhibited the post-initiation
phase of mammary carcinogenesis when it was given continuously
to the animals. In this report, experiments were carried out
in which treatment with the Se-garlic was started after carcinogen
dosing (DMBA or MNU) but was restricted to either the early
or late stage of neoplastic progression. The results from these
two models showed that a short-term exposure to the Se-garlic
for 1 month immediately following carcinogen administration
was just as effective in cancer prevention as the continuous
exposure regimen (5 months), suggesting that the Se-garlic may
irreversibly alter the process of clonal expansion and/or selection
of transformed cells during their early stage of development.
Plasma and mammary tissue selenium
levels essentially returned to basal levels at 1 month after
withdrawal of supplementation. These observations imply that
the outcome of cancer protection by short-term Se-garlic intervention
was not due to a slow turnover, and therefore a lingering presence,
of selenium in the target organ
or in the circulation. The above finding was in contrast to
that of a second study in which Se-garlic was supplemented starting
at 13 weeks after carcinogen treatment. With this protocol,
the number of new tumors and the number of new tumor-bearing
rats found during the intervention period (weeks 13 to 22) were
not statistically different between the control and supplemented
groups, suggesting that Se-garlic had a minimal effect on the
later stages of mammary carcinogenesis.
Carcinogenesis (United Kingdom)
, 1996, 17/9 (1903-1907)
Previous work has shown that
the efficacy of cancer prevention by selenium-enriched
garlic (Se-garlic) is primarily dependent on the action of selenium.
An aqueous extract containing 43 microg Se/ml was prepared from
lyophilized Se-garlic powder by the Soxhlet method. The activity
of this Se-garlic extract was evaluated in a transformed mammary
epithelial cell culture model for its effect on cell morphology,
cell growth, cell cycle progression and the induction of single
and double stranded breaks in DNA. Comparisons were also made
with a similarly prepared extract from regular garlic, Se-methylselenocysteine
(a major water-soluble seleno-amino acid identified in Se-garlic)
and selenite (used for fertilizing Se-garlic). In contrast to
the regular garlic extract which produced little or no modulation
of the above parameters, treatment with the Se-garlic extract
resulted in growth inhibition, G1 phase cell cycle arrest and
apoptotic DNA double strand breaks in the absence of DNA single
strand breaks. This pattern of cellular responses was duplicated
with exposure to Se-methylselenocysteine. Selenite, on the other
hand, induced cell cycle blockage in the S/G2-M phase, and a
marked increase in DNA single strand breaks (a measure of genotoxicity)
in addition to growth suppression. The chemopreventive efficacy
of the two garlic extracts was also investigated in the rat
methylnitrosourea mammary tumor model. Both extracts were supplemented
in the diet for 1 month immediately following carcinogen administration.
Significant cancer protection was observed with treatment by
the Se-garlic extract (at 3 p.p.m. Se in the diet), while little
benefit was noted with treatment by the regular garlic extract.
Based on the above in vitro and in who findings, it is hypothesized
that the Se-garlic extract, in part via the action of Se-methylselenocysteine,
is able to inhibit tumorigenesis by suppressing the proliferation
and reducing the survival of the early transformed cells. Furthermore,
the data also support the concept that the moduss of novel forms
of selenium for cancer prevention.
GAZZ.SANIT. (MILANO) (ITALY),
1973, 22/1 (37-39)
The incidence of multiple sclerosis
among predisposed subjects is higher in cold climates, and is
compounded where trace metals, such as copper, selenium
and cobalt, are lacking in the diet. The importance of trace
elements in various metabolic processes is discussed, including
the etiology of multiple sclerosis. Screening children, removing
those at risk to warmer climates and further research into trace
metal physiology are recommended.
Tuesday, December 02, 2008 by: Sherry Baker, Health Sciences Editor
(NaturalNews) After decades of attempting to fight AIDS with experimental vaccines and drugs, scientists have recently discovered how several natural substances could be powerful weapons against the disease. For example, in mid-November, UCLA AIDS researchers published research concluding that the herb astragalus contains a substance with the potential to possibly replace the side-effect plagued HAART (highly active antiretroviral therapy) currently used to treat AIDS patients. http://www.naturalnews.com/024799.html.
Now Penn State immunologists say they've documented how a micronutrient could help battle AIDS. Their findings, just published in the Journal of Biological Chemistry, show how selenium could dramatically put the brakes on the replication of HIV, the virus that causes AIDS.
Selenium is needed by the body to maintain normal metabolism. It's also increasingly being studied for its anti-cancer properties. Although other nutrients usually bind to proteins, selenium actually becomes incorporated into proteins, forming what are called selenoproteins. These selenium-containing proteins are believed to slow the spread of infections. However, when HIV infects a person, the virus manages to degrade selenoproteins, probably due to a protein, dubbed Tat, produced by the HIV virus. In particular, Tat seems to target a selenoprotein known as TR1.
But there may be a way to get around this degradation of selenoproteins -- supplementation with selenium. "Since HIV targets the selenoproteins, we thought that the logical way to deal with the virus is to increase the expression of such proteins in the body," K. Sandeep Prabhu, assistant professor of immunology and molecular toxicology at Penn State, said in a statement to the press.
To test their idea, the scientists isolated blood cells from human volunteers who did not have HIV. Then they infected those cells with the virus and added a form of selenium called sodium selenite to the cell culture.
The result? The added selenium inhibited the replication of the HIV virus at least 10-fold, in comparison to cell cultures with no added selenium. The scientists also selectively reduced the production pf the selenoprotein TRI. When there was less selenium-containing protein, the HIV virus replication soared 3.5 times. Bottom line: The research confirms that an increase in selenium in cells zaps replication of HIV while a reduction in the amount of selenium-containing TR1 protein gives the virus a boost.
"We have found that increasing the expression of proteins that contain selenium negatively affects the replication of HIV. Once we fully understand the function of these selenium proteins, it will give us a handle to come up with more effective drugs," said Dr. Prabhu in the prepared statement for the media.
Two more new studies offer additional evidence that selenium may impact the immune system. German scientists from St. Josefs-Hospital in Wiesbaden recently published a study in the Swedish medical journal Acta Oncologica that suggests the micronutrient could help prevent prostate cancer and prostate enlargement. The researchers found that whole blood selenium levels were significantly lower in all men tested who had prostate cancer or benign prostate hypertrophy (which can cause difficulty with urination) and concluded, "our findings may support the recommendation of selenium supplementation" to help prostate health. What's more, a study just published in the journal Molecular Nutrition and Food Research suggests enzymes that contain selenium have anti-oxidative and anti-inflammatory effects that could make them important in preventing prostate and colorectal cancers.
Too much selenium in can cause a condition called selenosis, resulting in loss of hair, nail problems, nausea, irritability, fatigue, and mild nerve damage. However, selenium toxicity is extremely rare. A lack of selenium may, in fact, be far more common and potentially more dangerous to health. According to the National Institutes of Health, people age 14 and older should take in about 44 micrograms of selenium a day. Good sources of the micronutrient include Brazil nuts, eggs, brown rice, whole wheat bread and pasta, walnuts and oatmeal.
About the author
Sherry Baker is a widely published writer whose work has appeared in Newsweek, Health, the Atlanta Journal and Constitution, Yoga Journal, Optometry, Atlanta, Arthritis Today, Natural Healing Newsletter, OMNI, UCLA's "Healthy Years" newsletter, Mount Sinai School of Medicine's "Focus on Health Aging" newsletter, the Cleveland Clinic's "Men's Health Advisor" newsletter and many others.
