Selenium

What is Selenium?
A nice review by students from the University of North Carolina School of Pharmacy

Selenium: Antioxidant & Cancer Quencher
Nutrition Science News (March 1999)
The mineral selenium has been gaining household recognition and respect in recent years by virtue of its addition to the list of nutritional antioxidants--substances that offer protection against our most dreaded diseases and aging. Indeed, selenium, as a component of several enzymes, does help rid the body of destructive oxidation products.

Selenium Stops Flu Mutations
Nutrition Science News (December 2001)
Because flu virus mutations create new virus strains each year, it becomes virtually impossible for the body's immune system to develop a permanent defense. However, taking adequate amounts of selenium can prevent those mutations from occurring. Melinda A. Beck, Ph.D., a virologist at the University of North Carolina, Chapel Hill, and her colleagues exposed two groups of laboratory mice to a relatively mild flu virus strain called influenza A Bangkok, which also infects people. Flu viruses infecting selenium-deficient mice developed 29 mutations, which led to greater virulence. In contrast, selenium-replete mice experienced no mutations in the infecting virus and had milder symptoms.

Dietary Antioxidant Health and Exercise
50th Annual meeting of the American College of Sports Medicine
San Francisco, USA May 2003
Professor Malcolm Jackson, from Liverpool University's department of medicine in the UK, presented data on the ability of subjects to rid themselves of a flu virus, with and without selenium supplementation. Subjects who supplemented with selenium (2 to 3 times the RNI) were able to rid their bodies of the virus significantly faster than the non-supplemented subjects. This study has many important implications. In addition to selenium's role in glutathione peroxidase metabolism, it has now been shown that selenium is also vital for optimal functioning of the immune system. These findings have broad-based implications and indicate that the current RNI for selenium is not high enough and may require revision. (This full abstract is no longer available online).

Selenium Supplementation and Exercise:
Effect on Oxidant Stress in Overweight Adults
Obesity (Silver Spring). 2011 (May 19) [Epub]
This new study suggests that selenium supplementation may reduce markers of oxidative stress especially in overweight adults who exercise. The randomized, double-blind study included 10 normal weight and 10 overweight adults who received either placebo or 200 micrograms of selenium daily for three weeks. At the end of three weeks, both groups received placebo for three more weeks and then crossed over to the opposite group. The results revealed that the overweight participants taking selenium supplements experienced a 0.25 micromole per liter decrease in lipid hydroperoxide levels immediately following exercise. It was also noted that the overweight participants had low selenium levels at the start of the study. In the overweight group, selenium supplementation was effective at increasing plasma selenium levels to near recommended levels which in turn decreased lipid hydroperoxide responses at rest and after high-intensity exercise.

Adaptive Dysfunction of Selenoproteins From the Perspective of
the Triage Theory: Why Modest Selenium Deficiency
May Increase Risk of Diseases of Aging
FASEB J. 2011 (Jun); 25 (6): 1793–1814 (Epub Mar 14)
The triage theory proposes that modest deficiency of any vitamin or mineral (V/M) could increase age-related diseases. V/M-dependent proteins required for short-term survival and/or reproduction (i.e., "essential") are predicted to be protected on V/M deficiency over other "nonessential" V/M-dependent proteins needed only for long-term health. The result is accumulation of insidious damage, increasing disease risk. We successfully tested the theory against published evidence on vitamin K. On modest selenium (Se) deficiency, nonessential selenoprotein activities and concentrations are preferentially lost, with one exception (Dio1 in the thyroid, which we predict is conditionally essential). Mechanisms include the requirement of a special form of tRNA sensitive to Se deficiency for translation of nonessential selenoprotein mRNAs except Dio1. The same set of age-related diseases and conditions, including cancer, heart disease, and immune dysfunction, are prospectively associated with modest Se deficiency and also with genetic dysfunction of nonessential selenoproteins, suggesting that Se deficiency could be a causal factor, a possibility strengthened by mechanistic evidence. Modest Se deficiency is common in many parts of the world; optimal intake could prevent future disease.

Selenium Biochemistry and Cancer: A Review of the Literature
Alternative Medicine Review 2004 (Sep); 9 (3): 239-258 ~ FULL TEXT
Animal data, epidemiological data, and intervention trials have shown a clear role for selenium compounds in both prevention of specific cancers and antitumorigenic effects in post-initiation phases of cancer.

Selenium Monograph
Alternative Medicine Review 2003 (Feb); 8 (1): 63–71 ~ FULL TEXT
This Adobe Acrobat article (67KB) states: The connection between selenium and cancer was originally demonstrated by correlation studies relating selenium levels in crops and cancer mortality rates. Broghamer reported that "Lower selenium levels in patients with carcinoma are likely to be associated with
(1) distant metastisis;
(2) multiple primary tumors;
(3) multiple recurrences; and
(4) short survival times."

Molecular Epidemiologic Studies Within the Selenium and
Vitamin E Cancer Prevention Trial (SELECT)
Cancer Causes Control 2001 (Sep); 12 (7): 627–633
To conduct timely epidemiologic investigations of molecular/genetic markers that may contribute to the development of prostate, lung, colorectal, or other cancers within the Selenium and Vitamin E Cancer Prevention Trial (SELECT), and to evaluate interactions between these markers and the study interventions.

Nutritional Aspects of Prostate Cancer: A Review
Can J Urol 2000 (Feb); 7 (1): 927–935
Incidence rates for prostate cancer vary according to diet and lifestyle. Several double-blind placebo-controlled clinical trials have shown that supplementation with selenium reduces cancer incidence. Inhibitory effects on the growth of in vitro prostate cancer cell lines have been observed with the administration of soy isoflavones, lycopenes from tomatoes, and vitamin D.

Impact of Trace Elements and Vitamin Supplementation on
Immunity and Infections in Institutionalized Elderly
Patients: A Randomized Controlled Trial.
MIN. VIT. AOX. Geriatric Network
Arch Intern Med 1999 (Apr 12); 159 (7): 748–754
Low-dose supplementation of zinc and selenium provides significant improvement in elderly patients by increasing the humoral response after vaccination and could have considerable public health importance by reducing morbidity from respiratory tract infections.

Effects of Selenium Supplementation for Cancer
Prevention in Patients with Carcinoma of the Skin
JAMA 1996 (Dec 25); 276 (24): 1957–1963
Selenium treatment did not protect against development of basal or squamous cell carcinomas of the skin. However, results from secondary end-point analyses support the hypothesis that supplemental selenium may reduce the incidence of, and mortality from, carcinomas of several sites.

The Effect of Dietary Levels of Selenium on Radiation
Resistance and Radiation–induced Carcinogenesis
Nutrition Research 1996; 16 (3): 505–516
A long–term experiment in 400 rats exposed to radiation following the Chernobyl pattern showed that a selenium–enriched diet started after exposure caused a longer average lifespan and a 1.5 – 3.5 fold decrease of leukaemias and other malignancies, e.g. breast, thyroid and lung cancers, etc., at late times. Selenium was first demonstrated to provide protection against late effects which is equivalent to a whole–body dose reduction by 1.4 Sv (140 rem).

A Preliminary Report on the Intervention Trials of
Primary Liver Cancer in High-risk Populations with
Nutritional Supplementation of Selenium in China
Biol Trace Elem Res 1991 (Jun);   29 (3):   289–94
The third trial was carried out in members of families with high Primary Liver Cancer (PLC) incidence using Selenium-yeast (200 micrograms of Se daily) vs placebo for 2 y. The results showed that nutritional supplement of Se could reduce the PLC incidence significantly.

Selenium Chemoprevention of Liver Cancer in Animals
and Possible Human Applications
Biol Trace Elem Res 1988 (Jan); 15: 231–241
Animal experiments demonstrated that supplementation of Selenium reduced the incidence of liver cancer in rats exposed to aflatoxin B1.