The Selenium Connection
© Robert Anderson PhD
 
 
I am not a great gardener, but I’ve always admired those who are. To be able to produce good quality vegetables must bring great satisfaction to those who can. This is particularly the case when most of the food for the developed world’s populations is produced by industrial agricultural methods. Frequently, such food not only lacks taste, but also the vital nutrients to keep our immune systems functioning. As the soils become more and more depleted so does the food grown in it.[i] We have plentiful evidence of this in the growing plethora of diseases forming the backdrop of our society. Being able to produce good wholesome organic food has thus become essential if we are to maintain health.
 
I realise I’m talking to the converted in our readership. However, many Kiwi gardeners are unaware of the fact that no matter how lovingly they produce vegetables, they will almost always lack enough of a most essential element, selenium.
 
Modern investigation is throwing up remarkable facts about this mineral. One of the foremost seleniophile giants in the field was Dr Jim Oldfield, emeritus professor of animal nutrition at Oregon State University in the US, who produced a selenium world atlas. This shows that the soils in the UK and NZ are low in selenium. Early NZ farmers discovered that selenium must be given to farm animals in order to maintain their health, but human beings have somehow been forgotten. As one medical friend said, “It’s because we are only of value when we’re sick.”
 
Even so, NZ is properly acknowledged as a pioneer for selenium animal research. NZ soils are depleted in this indispensable mineral[ii]and I do not agree with the US study[iii]conducted here. It found that, “selenium has low concentrations in most NZ soils, but there has been little indication that the low intake has resulted in any detrimental effects on the health of New Zealanders.”
 
Although selenium has been recognized as an essential micronutrient for around 50 years and has been effectively used as a supplement for livestock, similar use in the human diet has not been sufficiently pursued. This situation is changing and it is becoming more evident that selenium is not only a basic element in the human diet, it is essential for the human immune system. It offers a protective effect against a whole spectrum of diseases including breast, prostate and other cancers, and coronary disease. These findings are adding urgency to the need to maintain an adequate intake of selenium.

A vital catalyst
 
One of the most powerful antioxidants that our bodies produce is glutathione peroxidase. This complex sounding chemical acts as our ‘bass broom.’ It sweeps out toxic metals such as mercury from amalgam fillings, lead, and even uranium from exposure to the contaminated dust being spread through our global atmosphere as a result of the use of Depleted Uranium (DU) weapons in war zones. It also gets rid of the host of oxidation products produced by the normal life processes which take place in our body. But there is a catch. Which element wields this broom? Not surprisingly, it turns out to be selenium. It acts as a catalyst enabling glutathione to, firstly, form glutathione peroxidase, and then to combine with and remove dangerous contaminants. Glutathione peroxidase contains four selenium atoms in every molecule and its activity is increased by selenium dietary intake.
 
The health protective effects of selenium are truly enormous. Investigators at Otago University have long monitored selenium nutrition in NZ and have shown that higher selenium intakes are providing protection against cancer and even psychological functions.[iv] Let’s look at just how important this mineral is to our health.
 
It has been well reported that NZ has high rates of asthma. Children with asthma have been observed to have significantly reduced red blood cell glutathione peroxidase activity when compared to healthy children.[v] This is substantiated by the findings of later research showing decreased levels of selenium in asthmatics.
 
Studies published in 2004 showed benefits of selenium in the prevention of prostate cancer. One particular epidemiological study, published in May 2004 in theJournal of the National Cancer Institute, revealed that men with high blood levels of selenium were half as likely to develop prostate cancer as the men with lower blood selenium. Several other recent studies suggest that low blood selenium may be associated with increased risk of colon cancer. Yet another study, published in August 2004, revealed that selenium may prevent gastric cancer, especially in men.
 
Supplements and natural products like garlic cannot be patented and therefore do not generate the enormous profits associated with pharmaceutical drugs, so they are generally ignored as potential life-savers. In the UK, plans for a major trial to assess the anti-cancer powers of selenium were dropped by the Medical Research Council,[vi]possibly for these reasons. A US study showed that people given selenium supplements were found to have 50 per cent less chance of dying of cancer compared with individuals who had poor levels.
 
Dr Martin Smith of Indiana University found that selenium helps activate a gene (called p53) which makes a chemical that suppresses tumours. Dr Larry Dark of Arizona University found that, of 1300 individuals previously treated for non-melanoma skin cancers, those participants given selenium supplements had their cancer death rates halved, compared with those given placebos. Selenium found in ‘high selenium yeasts’ - containing as much as 1000 to 2000 μg (micrograms) of selenium per gram - was used in a large scale cancer prevention trial in 1983. It clearly demonstrated that taking a daily supplement containing 200 μg of selenium per day could lower the risk of developing prostate, lung and colorectal cancer.[vii]
 
New Zealand has the third highest incidence of cancer in the world and it is increasing at seven percent per year. Breast cancer is the commonest form of cancer in women and BreastScreen Aoteraroa claims that ten percent of woman can expect to get it. Recent research[viii]suggests that selenium may help protect some women from developing breast cancer. The conclusion was that certain women - with a certain genetic makeup – may well benefit from extra selenium in their diet to make sure their “cancer-fighting” enzyme works properly.
 
Manifestly, there is ample evidence supporting selenium supplementation, but perhaps the most amazing findings are those associated with AIDS. Dr William Hasteltine said in a 1992 lecture to the French Academy of Sciences that, “The future of AIDS is the future of humanity.” Hasteltine, chief retro-virologist at Harvard’s Dana-Farber Cancer Institute, added that, “Unless the epidemic of AIDS is controlled, there is no predictable future for our species.” A grim statement indeed. Obviously, any breakthrough would be a light at the end of the tunnel. It is now well-established that individuals who are HIV-positive gradually become increasingly selenium deficient.[ix]
 
A very remarkable quality of selenium is that it inhibits virus mutation. It has been noted that in Dakar, Senegal’s major urban centre, HIV-1 prevalence among women attending antenatal clinics has remained at one percent or less, from when surveillance began in the mid-1980s until 1998. Why would this be? Unlike many other sub-Saharan African countries, Senegal has areas rich in selenium.[x] Conversely, a link between elevated AIDS mortality and depressed environmental selenium has been shown to occur in the US.
 
It has been found that adding this trace element to diets opens new avenues for both the prevention and treatment of disease.[xi] This strategy has also been shown to work on other viruses that encode glutathione peroxidase, such as Hepatitis B and C, and the Coxsackie virus. China also has areas of selenium deficiency, and has compensated by adding this element to their diets. Everywhere in the Chinese selenium deficiency belt, as the level of this trace element has risen in local diets, Coxsackie and other virus infections have fallen and, with it, Keshan disease,[xii]a fatal disease of the heart muscle.
 
A study in Clinical Chemistry reported that patients with healthy hearts had higher levels of selenium than patients with blocked arteries. Surveys also indicate that individuals with rheumatoid arthritis have reduced selenium levels in their blood.[xiii] In addition, some individuals with arthritis can have a low selenium intake.[xiv] The recommended daily selenium dose for people with diabetes[xv]is 400 micrograms, considerably more than the FDA’s recommended daily intake.
 
A recent move by the NZ government is the proposal to allow our dietary supplements to be controlled by the Australian Therapeutic Goods Administration (TGA). Even though no deaths are recorded from dietary supplements, this regulation will be strictly imposed. Why? It has been suggested that it is because the pharmaceutical giants want to close the leak of an at least US$6 billion annual turnover on dietary supplements by pressurising the Codex Alimentarius. As my medical friend pointed out, “… we are only of value when we’re sick.”
 
When it comes to such “toxic” chemicals as selenium, the quantities made available will probably be inadequate for maintaining optimum health. At the moment, this should be 200 micrograms (μ g) daily. With immune-compromised adults, or those having a large number of mercury amalgams, it could be double that figure.[xvi] Recommendations for selenium intake are provided by the US Food and Drug Administration (FDA), but the Recommended Daily Allowances[xvii](RDA) they give are normally too low at 70 μ g/day for men and 55 μ g/day for women.
 
Selenium toxicity is rare. In fact, the amount of selenium that would cause toxicity in humans is not known.[xviii] The few reported cases have been associated with industrial accidents or a manufacturing error that led to an excessively high dose of selenium in a supplement.[xix] The only published case of selenium poisoning[xx]occurred when a patient took 10 tablets a day for 2 weeks together with a supplement containing an unknown amount of selenium. During this time, he developed diarrhoea, worsening fatigue, and a tingling sensation in the extremities and became completely bald. Only two weeks after discontinuing the supplement, however, he appeared healthy with re-growth of hair and normal neurological examination.

So what can we conclude? Growing your own
 
There is mounting evidence that it is necessary we increase the selenium in our diets. Even with the best grown organic foods, we may still be deficient in this vital mineral. Exposure to the stress of modern living and its pollutants, requires that we be particularly watchful of our immune systems.
 
The amount of selenium taken up by vegetables is, as we would expect, dependent on the selenium content of the soil. For those keen on getting it from home-grown food, a good selenium compost dressing would be essential. For the home gardener, we find a number of factors influence the uptake of selenium in plants.[xxi] Some plants, even if grown in selenium rich soils, offer only a marginal uptake. For example, wheat samples gathered from different locations around the world recorded levels of only 0.1 to 1.9 ppm of selenium,[xxii]well below desirable levels. So, not only is it necessary to dress our soils with selenium rich compost, it requires a careful choice of plants which take up this element. Are there plants that would concentrate this element? It seems there are.
 
Rapeseed or canola (Brassica napus), generally grown commercially for cooking oil, has shown great potential for uptake of selenium in soils.[xxiii] It is a good crop to dig back into the ground. It typically shows selenium concentrations of several hundred mg Se/kg dry weight (dw) when grown in soils with even moderate levels of selenium. Garlic is another plant able to concentrate selenium. In India, a study found that two other common leafy vegetables - mustard (Brassica campestris) and spinach (Spinacea oleracea) - increased their selenium uptake from enriched soils.
 
The edible button mushroom, Agaricus bisporus, is a good candidate. The rapid growth of interest in medicinal mushrooms research[xxiv]is matched by the large number of groups that offer a wide range of publications. For example, the International Journal of Medicinal Mushrooms draws together most aspects of this expanding field and will keep you up to date with the latest issues and practice. In one trial, selenium concentrations added to the compost in which mushrooms were grown were from 30 to 300 ppm (dw) and uptake by the mushrooms increased in a linear fashion as the level of selenium added to the compost increased. As expected, this decreased with each new crop cycle.
 
For gardeners who prefer that their own produce provide their selenium, a whole world is out there to explore. One thing is for sure, the plants you eat will have a whole lot more protective qualities than most commercially grown crops. Happy gardening!
 
 
 
Robert Anderson BSc (Hons), PhD (4 February 1942 to 5 December 2008)
 
Robert Anderson was a Trustee of Physicians and Scientists for Responsible Genetics (now Physicians and Scientists for Global Responsibility) www.psgr.org.nz.  He authored The Final Pollution: Genetic Apocalypse, Exploding the Myth of Genetic Engineering and several other publications on environmental, health and social justice issues.
 
View Robert Anderson’s lectures on this site.
 
Address enquiries for Robert Anderson's publications to naturesstar@xtra.co.nz.
 
 
References:
 
 
[i] Davis D., Science confirms organic sector warnings. NZ Organic July/August 2006 pp14
[ii] Wells, N., 1967. Total selenium in top soils. NZ Soil Bureau Atlas89-90 Govt Printer Wellington.
[iii] Duffield AJ, et al. An estimation of selenium requirements for New Zealanders. Am J Clin Nutr 1999;70:896-903.
[iv] Duffield et al., 1999 Otago University.
[v] Powell CV, et al. Antioxidant status in asthma. Pediatr Pulmonol1994;18:34-38.
[vi] Cash crisis kills off trial of 'life-saver Robin McKie, The Observer, 20-1-02.
[vii] Clark LC, et al Effects of selenium supplementation for cancer prevention in patients with carcinoma of the skin. A randomized controlled trial. J Am Med Assoc 1996;276:1957-63.
[viii] Brazil nuts protect from breast cancer. Public Health News 17 Jun 2003. Journal Cancer Research.
[ix] Baum, M.K., Shor-Posner, G., Lai, S., Zhang, G., Lai, H., Fletcher, M.A., Sauberlich, H., and Page, J.B. (1997). High risk of HIV-related mortality is associated with selenium deficiency. Journal of AcquiredImmune Deficiency Syndromes and Human Retrovirology, 15(5), 370-374.
[x] Gulbrandsen, R.A., Geochim. Cosmachin. Acta 1966; 30:769, cited by E.A. Keller, Environmental Geology, Upper Saddle River, Prentice Hall, New Jersey, 1996, p. 352.
[xi] Foster, H.D. (2000). Aids and the “selenium-CD4T cell tailspin”: The geography of a pandemic. Townsend Letter for Doctors and Patients, 209, 94-99.
[xii] Editorial Board, The Atlas of Endemic Diseases and the Environment in the People's Republic of China, Science Press,Beijing, 1985, pp. 42-83. Wells, N., 1967. Total selenium in top soils. NZ Soil Bureau Atlas89-90 Govt Printer Wellington.
[xiii] Kose K, et al Plasma selenium levels in rheumatoid arthritis. Biol Trace Elem Res 1996;53:51-6.
[xiv] Stone J, Doube A, Dudson D, Wallace J. Inadequate calcium, folic acid, vitamin E, zinc, and selenium intake in rheumatoid arthritis patients: Results of a dietary survey. Semin Arthritis Rheum 1997;27:180-5.
[xv] www.diabeteshealth.com
[xvi] Personal communication with Dr M. Godfrey, Director Environmental Health Clinic Tauranga.
[xvii] Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes: Vitamin C, Vitamin E, Selenium, and Carotenoids. National Academy Press, Washington, DC, 2000.
[xix] Hathcock J. Vitamins and minerals: Efficacy and safety. Am J Clin Nutr 1997;66:427-37.
[xx] Clark RF, et al. Selenium poisoning from a nutritional supplement. JAMA1996;275:1087-8.
[xxi] Johnson C.M. et al 1967 Distribution of selenium in plants. In: Selenium in biomedicine Ed. O.H.Muth AVI Publishing Co Westport, CT pp 57-75.
[xxii] Robinson, W.D. 1936. Selenium content of wheat from various parts of the world. Ind. Eng. Chem. 28:736-742.
[xxiii] Bañuelos GS et al. (1997a) Evaluation of different plant species used for phytoremediation of high soil selenium. Journal of Environmental Quality. 26:639-646.
[xxiv] Zaidman BZ, et al. Medicinal mushroom modulators of molecular targets as cancer therapeutics. Appl Microbiol Biotechnol. 2005 Jun;67(4):453-68. Epub 2005 Feb 23.