Anti-Oxidants: Magic Molecules Against Pro-Oxidant Menace?


By Zeenat Farooq

ANTI-OXIDANTS are the substances which quench pro-oxidants in an oxidation-reduction reaction. These can vary in chemical structure and complexity ranging from simple substances like ascorbic acid (Vitamin C) to complex metabolites like vitamin-E, glutathione and Uric Acid. Some of these anti-oxidants are naturally produced within our bodies while some are supplied from external sources like β-carotene (pro-vitamin A) from carrot, lycopene (the pigment which imparts redness) from tomatoes etc.

Oxidants produced in our body are mostly the reactive oxygen species (ROS) like superoxide radicals, hypochlorous acid, peroxide radicals etc, and to a lesser extent, reactive nitrogen species. These free radicals are mostly produced within the electron transport chain as by-products during oxidation of food for production of energy inside mitochondria. The problem with these free radicals is that these are extremely reactive, considering the fact that these have un-paired electrons inside and hence can react at random with various bio-molecules within the body. Some of these are so reactive that these can cause chain reactions which can prove very troublesome like lipid per oxidation in which ROS react with the lipid molecules of our cells and hence disturb their integrity. This mechanism can have serious consequences if left unchecked.

Oxidants or pro- oxidants are also involved in ageing in general, as one of the famous theories on ageing: the “wear and tear theory” suggests that “with increase in age, there is increase in pro-oxidant accumulation and hence more wear and tear to cells which causes aging”. Another similar theory relates pro-oxidant accumulation and aging to food consumption by stating that “the more you eat, the more you age”. There is a logical reason behind these aforementioned theories as already stated that ROS is basically produced during food oxidation. Hence, if we keep checks and balances on our food consumption, we can maintain the levels of ROS being produced. Also, with aging, the scavenging mechanism which keeps check on ROS levels begins to weaken. Therefore, there is higher level of ROS generation and consequently more lipid per oxidation and wear and tear.

Anti-oxidants remain one of the favourites, especially for dieticians and anti-oxidant supplement and tonic manufacturers since these are the substances which scavenge ROS and protect us from their harmful effects. For example, Vitamin C accelerates wound healing; Uric acid has protective benefits against Multiple Sclerosis (MS). In fact, it has been observed that patients with hyperuricemia (Gout) are rarely afflicted with MS. There are also some studies performed in model organisms which state that anti-oxidants have a protective benefit against neurodegenerative diseases like: Alzheimer’s and Parkinson’s, cardiovascular diseases and also cancer.

So far, it seems as if the pro-oxidants are real villains of our body. This also represents anti-oxidants as “magic molecules” which can rid of the menace of ROS, as is usually speculated by our media and perceived by common people. It is because of this common belief that even tooth paste companies now claim to make “anti-oxidant rich tooth pastes which protect the teeth against ROS”. But the fact still remains that are these only waste by-products produced by the body which only harm our system? And if so, why does the body produce such substances at the first place? This belief or myth is far from truth as the pro-oxidants perform various functions in our body which are of vital consequence.

These act as signaling molecules in various cell communication pathways.

These play an important role in our immune system as our immune cells impart oxidant stress to infecting bugs in order to eliminate them.

These molecules are also important in limiting cancer growth as cancer cells also experience increased oxidative stress imparted by immune cells to contain cancer growth. In fact, it has been studied that additional anti-oxidant supplementation interferes with chemo and radiation therapy in some cancer forms. Also, increased anti-oxidant supplementation enhances the likelihood of smokers to develop lung cancer.

Tail Piece

In the light of above mentioned facts, anti-oxidants and pro-oxidants should be considered as opposing forces in a biological system where each has its given role to maintain the equilibrium state of our body and an imbalance on either side can have dire consequences. Therefore, the next time you hear about benefits of anti-oxidant supplements and tonics, do a double check before you buy one. Anti-oxidants are certainly beneficial substances and some people might also need additional supplementation under some conditions but like any other supplement, these should not be consumed without proper medical supervision. Rather we should balance our food intake and rely more on natural anti-oxidant sources like green tea, tomatoes, oranges, spinach, carrots so as to enjoy the benefits of anti-oxidant power without experiencing the ill effects of over consumption of anti-oxidants and disturbing the pro-oxidant signalling mechanisms.

(Author is a Research Scholar at Department of Biotechnology, University of Kashmir.)


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