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Antioxidants can Accelerate Cancer, ya really!

Oh rly?

Oxidative stress on the body caused by free radicals, billed as a bad thing. Fruits, veggies and just about anything with the word healthy in the title is “jam packed” with antioxidants. But they don’t provide the health benefit the are billed to have, that’s because oxidative stress isn’t a bad thing for the body in some cases. Now researchers have shown that antioxidants can accelerate cancer and we also know why.

First antioxidants are chemicals that stop oxidation[also known as free radicals], simple enough, right? Oxidative stress on the body can be a bad thing, it can alter genetics, cause all sorts of random problems and generally needs to be kept under control. Yet clinical trials of antioxidant supplements have repeatedly dashed the hopes of consumers who take them hoping to reduce their cancer risk. Virtually all such trials have failed to show any protective effect against cancer.

In fact, in several trials antioxidant supplementation has been linked with increased rates of certain cancers. In one trial, smokers taking extra beta carotene had higher, not lower, rates of lung cancer. It sounds counterintuitive given that cancers can be caused by mutation so the idea that, in simple terms: oxidation —> mutation —> cancer —-> more oxidation —-> more cancer means that antioxidants should prevent all that.

However, researchers are now offering a reason why antioxidant supplements might not be working to reduce cancer development, and why they may actually do more harm than good. Their insights are based on recent advances in the understanding of the system in our cells that establishes a natural balance between oxidizing and anti-oxidizing compounds. These compounds are involved in so-called redox [reduction and oxidation] reactions essential to cellular chemistry and life for you and me.

Oxidants like hydrogen peroxide are essential in small quantities and are manufactured within cells. There is no dispute that oxidants are toxic in large amounts, and cells naturally generate their own antioxidants to neutralize them. It has seemed logical to many, therefore, to boost intake of antioxidants to counter the effects of hydrogen peroxide and other similarly toxic “reactive oxygen species,” or ROS, as they are called by scientists. All the more because it is known that cancer cells generate higher levels of ROS to help feed their abnormal growth. Hence my simple diagram earlier.

Researchers propose that taking antioxidant pills or eating vast quantities of foods rich in antioxidants may be failing to show a beneficial effect against cancer because they do not act at the critical site in cells where tumor-promoting ROS are produced — at cellular energy factories called mitochondria. Rather, supplements and dietary antioxidants tend to accumulate at scattered distant sites in the cell, thus leaving tumor-promoting ROS relatively unperturbed.

Quantities of both ROS and natural antioxidants are higher in cancer cells — the paradoxically higher levels of antioxidants being a natural defense by cancer cells to keep their higher levels of oxidants in check, so growth can continue. In fact, say researchers, therapies that raise the levels of oxidants in cells may be beneficial, whereas those that act as antioxidants may further stimulate the cancer cells.

Interestingly, radiation therapy kills cancer cells by dramatically raising levels of oxidants. The same is true of chemotherapeutic drugs – they kill tumor cells via oxidation. So it should be noted that oxidation in the body is a good thing, in fact it is one of the ways your body protects itself from diseases and random illness.

Paradoxically, then, the authors suggest that “genetic or pharmacologic inhibition of antioxidant proteins” — a concept tested successfully in rodent models of lung and pancreatic cancers — may be a useful therapeutic approach in humans. The key challenge, they say, is to identify antioxidant proteins and pathways in cells that are used only by cancer cells and not by healthy cells. Impeding antioxidant production in healthy cells will upset the delicate redox balance upon which normal cellular function depends.

The authors propose new research to profile antioxidant pathways in tumor and adjacent normal cells, to identify possible therapeutic targets. So once again we are left to say that this is why people shouldn’t  trust “alternative” medicine. Just because oxidation is bad in some cases does not make it bad in all cases. Redox reactions are important in the body which is why Doctors don’t go giving people antioxidants all willy nilly [yes, its the technical term].

ya rly

Want more? Then you can find the full study —here!

Phimister, E., Chandel, N., & Tuveson, D. (2014). The Promise and Perils of Antioxidants for Cancer Patients New England Journal of Medicine, 371 (2), 177-178 DOI: 10.1056/NEJMcibr1405701

5 responses

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