We are told increasing the amount of antioxidants in our diets as pills or foods will lower the chance of cancer, but a new study sheds light on reality which is completely opposite to this previously held belief. In fact, antioxidants accelerate cancers, do more harm than good and they, in no way suppress cancers.
Virtually, all the clinical trails conducted have failed to show any protective effect of antioxidant against cancer. In fact, in several trails they have been shown to increase cancer risk; example – in one trail, smokers were given extra beta carotene which dramatically increased their risk of getting lung cancer.
In a paper published in The New England Journal of Medicine, David Tuveson, M.D. Ph.D., Cold Spring Harbor Laboratory Professor and Director of Research for the Lustgarten Foundation, and Navdeep S. Chandel, Ph.D., of the Feinberg School of Medicine at Northwestern University, reason why antioxidant supplements might be doing more harm than good.
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Redox or oxidation-reduction reactions are essential to cellular metabolism and recent studies have helped scientists understand the natural balance between oxidizing and antioxidizing compounds in the body. Oxidants like hydrogen peroxide are needed in small quantities, they are toxic in large amount and the small amount required is manufactured within cells. When the amount of oxidants increase a certain limit, the cell produces its own antioxidants to neutralize them. So, logically it would seem that increasing antioxidant intake would boost the neutralization of “reactive oxygen species,” or ROS. Besides, cancerous cells are known to produce a large amount of ROS to maintain abnormal growth.
Now what the researchers have proposed is that taking antioxidants pills or large amount of foods containing them fails to protect against cancer because ROS in cancerous cells are produced in mitochondria and these antioxidants from foods or pills accumulate at scattered distant sites in cells leaving ROS in mitochondria unaffected.
Another reason why antioxidant intake promotes cancer is both ROS and antioxidants are present in large quantities in cancerous cells; antioxidants are produced to neutralize ROS which in turn promotes cancerous cell growth just like it does in normal cells. So, instead of raising the levels of antioxidants, it is the levels of oxidants that should be raised, so that the growth of the cell can be halted (as oxidants would increase and antioxidants will decrease, the cell will stop growing and reproducing). That is exactly what happens in both radiotherapy and chemotherapy; these methods kill the cancerous cells by dramatically raising the levels of oxidants.
Thus, the new way to consider curing cancer is to inhibit the antioxidant proteins genetically or pharmacologically. In fact, that concept has been successfully tested in rodents and can be used to cure cancer in humans as well.
The only challenging task that remains is to identify antioxidant proteins and pathways in cells that are used by cancer cells only and not by healthy cells. Much more research is needed before scientists can come up with a new or improved therapeutic technique to fight cancer based on this concept.
- Reference: The Promise and Perils of Antioxidants for Cancer Patients [NEJM]
- Source: Cold Spring Harbor Laboratory
- Image: Med-Health