beyond selenate . . . beyond selenomethionine . . .
beyond whole selenized yeast . . .

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Heart disease remains the number one cause of death in the developed world … yet dying of cancer continues to evoke the greater fear. Indeed, many people who wouldn’t otherwise become health-conscious will suddenly change their lifestyles when this killer breaks into their lives.

We know a lot about the lifestyle choices that can protect a person against cancer: a diet rich in fruits and vegetables, regular exercise, and avoiding carcinogenic compounds from cigarette smoke to fungal toxins are proven ways to reduce your risk. But today’s science lets us be a lot more specific than these broad guidelines. Beyond making shifts in consumption of whole food groups, there’s quite a bit of evidence that getting more of certain specific vitamins, minerals, and phytonutrients reduces your risk of cancer. And at the top of the list is selenium.

Starting in the 1960s1 and continuing through to today,2 a mountain of evidence – from animal and test-tube studies, to research comparing the risk of cancer among and within populations with different dietary selenium intakes or soil, water, or crop selenium levels – has accumulated to back up selenium’s cancer-fighting reputation.3 The most powerful evidence to date has come in the form of the “gold standard” of scientific proof: a large-scale, randomized, double-blind, placebo-controlled trial.4

This study – in which over 1300 patients with existing skin cancer participated – found that, while it had no effect against skin cancer, a 200 microgram selenium supplement cut the incidence of new cancers by 37%, slashed cancer deaths by 50%, and reduced death from all causes by a remarkable 17% as compared to a placebo.4 The trial was able to document specific reductions in lung and colon cancers,4 and an especially remarkable effect against prostate cancer: later analysis revealed that men taking the selenium supplement were only 37% as likely to suffer this fate as were men who had received the dummy pill.5

That’s the good news. Now get ready for even better news. As scientists have learned how selenium is metabolized in the body, they’ve also come to a new understanding of the
biochemical processes that underlie selenium’s anti-cancer effects. And with these insights, researchers have been able to do what they’ve never been able to do before: to identify
specific forms of selenium whose biochemical characteristics make them most readily used by the body to create potent cancer-fighting metabolites. The bottom line: over the course of the last decade, science has discovered a naturally-occurring form of selenium which is simultaneously more potent in its cancer-battling prowess, and less toxic per unit of cancer-fighting punch, than any other selenium supplement available.

This breakthrough selenium compound is Se-methylselenocysteine – often referred to by its initials as SeMC. And with the coming of the twenty-first century, its time has come.

It’s Not the Antioxidant Effect!
The first thing to get your head around is the fact that selenium’s most important anti-cancer effects – and the unique combination of cancer-fighting prowess and low toxicity seen in SeMC – have nothing to do with the mineral’s antioxidant activity. Popular books and magazines are still trotting out the notion that selenium fights cancer because it’s an antioxidant, used as part of the antioxidant enzymes glutathione peroxidase (GSH-Px) and thioredoxin reductase (TrxR). By fighting off free radicals, it’s said, these selenium-containing enzymes could prevent the damage to DNA that can ultimately turn a healthy cell into a consuming enemy within. But while selenium is certainly important as an antioxidant, the idea that antioxidant activity explains selenium’s anti-cancer effects has been abandoned by researchers, because it just can’t be squared with the latest science on how selenium is handled in the body.

Careful studies in the role of selenium in protecting animals from experimental cancer clearly show that the strongest anti-cancer effect is achieved at intakes far greater than the dosages at which antioxidant enzymes max out. That is, your body doesn’t just keep pumping out more and more selenium-dependent proteins as you take in more and more selenium: at surprisingly low levels, the production of these enzymes reaches a plateau. In humans, levels of key selenium-based enzymes reach a plateau level when your whole-blood or plasma selenium concentrations reach about 90 to 100 nanograms per milliliter6-9 – levels achievable after8 consuming just 40 micrograms of supplemental selenium a day.8,9 As intake of selenium increases beyond this basic nutritional level, there is a temporary jump in TrxR’s levels and/or activity, but the increase fades away with time.10-12 Yet the amount of selenium which maximizes the anti-cancer effect is much greater than this – and also greater than the amount needed for detoxification of some cancer-causing chemicals, or for the enhancement of the immune system, which were also once put forward as possible explanations for selenium’s cancer-quashing effect (see Figure 1).

In fact, there is even more direct proof that boosting antioxidant and detoxification enzymes are not the basis for selenium’s anticarcinogenic prowess. When you feed laboratory animals the same amount of selenium in either an organic form (selenomethionine, the form used in most supplements and the main form of selenium in selenium-yeast supplements) or the two common inorganic forms (selenite and selenate), selenomethionine gives the animals the greatest boost in antioxidant glutathione peroxidase activity … yet the two inorganic forms are the more effective cancer-fighters.13,14 Likewise, inorganic selenium’s greater cancer-battling properties can’t be explained by its effects on detoxification enzymes like glutathione transferases, because these forms of selenium are equal to selenomethionine in their ability to elevate this enzyme.13

Furthermore, there is a disconnect between the tissue levels of selenium that you get after consuming a given amount of a particular form of the mineral, and the strength of the anti-cancer effect of that form of selenium. Again using the more common forms of the supplement, scientists have shown that, over a wide range of doses, taking a given amount of selenium in the form of selenomethionine causes more selenium to accumulate in your tissues than taking the same amount of selenium as selenite or selenate– yet, once again, selenite and selenate consistently outperform selenomethionine when tested as cancer shields.13,14 In one study, in fact, either selenite or selenate provided a measure of protection against the earliest stages in cancer development at dosages where selenomethionine was totally without effect.16

An even stronger rebuttal of the idea that simple levels of selenium were decisive in the mineral’s anti-cancer effect came from feeding animals a constant level of selenomethionine, but in combination with either a standard diet, or a diet designed to inhibit the body’s accumulation of selenium from this form of the mineral. The result: the diet that reduced the body’s retention of selenomethionine actually enhanced its anti-cancer effect!17 Yet when animals were fed selenite (whose tissue accumulation is not affected by the same dietary manipulation), the mineral’s cancer-shielding capacity was unaffected by the same
changes in the diet.17

These studies parallel findings in studies of the relationship between selenium status and vulnerability to cancer in large human populations. In these studies, when selenium status is measured using higher intake of the mineral in the diet, a protective relationship is almost always reported.2,3,18 Yet when the amount of selenium that has been accumulated by the body is measured, there is no consistent association.2,3,18 In one especially revealing study,18 women with the highest dietary intake of selenium were nearly 38% less likely to suffer breast cancer than were women whose intake was lowest … yet there was no connection between breast cancer risk and plasma, red blood cell, or toenail selenium levels in the same women!

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For more information on Selenium, please click below.
Selenium Article 2, Selenium Article 3