The Daily Mail.co.uk
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A single nutrient - selenium - has been shown to hold great promise in the war against cancer, and may also help to combat conditions as diverse as infertility, dementia, low thyroid function and Aids.
On Christmas Day 1996, a scientific study was published which demonstrated selenium's ability to halve deaths due to some cancers. Since then the focus of much scientific research, it is clear that selenium's health-giving properties are nothing short of remarkable.
So, what is known about selenium's effects in the body, and how can it be used to enhance disease prevention?
Selenium is what is known as a 'trace mineral' - a nutrient which is only required in very small amounts by the body. Despite the fact that we don't need much of it, the importance of selenium intake is no more starkly demonstrated than in the case of cancer.
At the heart of the cancer-causing process are destructive molecules called 'free radicals' - byproducts of the reactions which generate energy in the body. By damaging sensors on the surface of the cell or the DNA within it, they can trigger the development of cancerous cells. Another effect free radicals have is to suppress the body's immune system.
Fortunately for us, free radicals are controlled in the body by antioxidants. Selenium is known to have potent antioxidant activity, which in theory should give it cancer protective effects.
However, selenium has another trick up its sleeve: it stimulates the immune system, and so appears to help the body kill off very early tumours.
Since the Seventies it has been noted that individuals with the lowest intakes of selenium have the highest risk of dying from cancer. However, the 1996 selenium study was the first research to look at whether or not taking selenium could reduce cancer risk.
This study involved more than 1,300 individuals, all of whom had a history of skin cancers other than the melanoma type. Half the group was given selenium as a supplement, the other half a placebo (inactive pill).
After about four years it was found that the group taking selenium had half the risk of dying from cancer compared to those taking placebos. While selenium had no effect on skin cancer risk, it did bring about very significant reductions in the risk of cancers of the prostate, colon, lung, etc.
A European study is now under way which will look at the effect of selenium on cancer risk in 42,000 individuals. If the trial's findings, due to be announced in five years time, prove as positive as the researchers expect, selenium will establish itself as an effective anticancer agent.
Recent research also suggests that selenium may well have a significant role to play in the prevention of another killer - Aids. Those with low levels of selenium in their bodies are nearly 20 times more likely to die from Aids.
Another important function of selenium relates to its role in reproduction. Selenium has long been used in the world of animal husbandry to prevent miscarriage. Women prone to miscarriage tend to have low levels of selenium in their systems.
Selenium seems to play a part in male fertility, too. One study demonstrated that supplementation with this nutrient increased fertility in a group of men with poor sperm quality.
Selenium also has a role to play in the functioning of hormones manufactured by the thyroid gland. Selenium may help individuals with low thyroid function, including those taking thyroxine medication.
The multifaceted benefits of selenium even extend to the brain. Selenium plays a part in the manufacture of brain chemicals known as neurotransmitters, and low levels of selenium in the elderly are linked with an increased risk of dementia and senility.
So, where is this most versatile of nutrients to be found? The best food sources are kidneys and Brazil nuts. Other reasonable sources include shellfish, fish, liver, red meat, poultry and wheat.
However, anyone wanting to ensure an adequate intake of selenium would do well to consider supplementation. Selenium supplements, often combined with other antioxidants such as vitamins A, C and E, are widely available in health food stores. The dose of selenium usually recommended is 200 micrograms a day.
http://www.dailymail.co.uk/health/article-5009/How-diseases-selenium-beat.html
