Our bodies are like a factory, constantly working to maintain life. Our cells take in nutrients and use them to create energy, hormones, proteins and other compounds that we need to live. Like any process, by-products are produced. These by-products are known as free radicals, which are highly reactive molecules that if left unchecked, will react with other compounds or structures in our cells and damage them over time as well as create more free radicals in the process. These free radicals are different forms of oxygen molecules also known as Reactive Oxygen Species (ROS). Some of these ROS’s are hydrogen peroxide (H2O2 ), Hydroxyl free radicals (-OH) and the dangerous superoxide anion (O2–). Fortunately, our cells have developed quite a few ways to counter free radicals so that they are less likely to harm our body.
Antioxidants (Anti – “against”, Oxidant – “oxidizer”) work by neutralizing free radicals. Antioxidants do this by accepting the unpaired electron(s) that free radicals have hanging off of them. This is what causes free radicals to be so reactive. They want to balance themselves out by “assaulting” another molecule or ion for one of their electrons. This balances out free radicals so that they will not cause any more damage. In other words, antioxidants in your body take the hit from free radicals so you don’t have to. One of the unique ways our body does this is by taking advantage of a close relationship between a specific group of antioxidants, in order to neutralize free radicals: Vitamins A, E, and C.
Vitamin A (beta carotene or ß-carotene) is a molecule that has several roles in your body, one of which is an antioxidant. This vitamin does not dissolve in water because it’s hydrophobic (hydro – “water”, phobic (phobos) – “fear”). However, it does dissolve in oil or fat which makes it lipophilic (lipo – lipid/fat, philic (philos) – “friend”). Vitamin A travels deep in the membranes of our cells scavenging out free radicals.
Vitamin E (alpha-tocopherol) is much like vitamin A in that it’s lipophilic. It is an even stronger antioxidant than vitamin A. However, it does not like to travel deep within cell membranes but just below or near the surface of our cells scavenging free radicals there.
One of the reasons why this vitamin is so powerful and essential to our health, is that it stops the chain reaction that free radicals create when they react with other molecules. This chain reaction creates more free radicals since they rob other molecules of electrons in order to balance themselves out. Vitamin E has the capacity to stop this reaction in its tracks so the free radical cascade can not continue.
Vitamin C (ascorbic acid) is also a powerful antioxidant like vitamins A and E. We have far more of this vitamin in our body than vitamins A and E. Vitamin C is hydrophilic (hydro – “water” philic – “friend”). It dissolves in water instead of fats or oils. What makes this vitamin different from the other two is that it dissolves in your blood, which is largely made up of water. Vitamin C is one the first lines of defense against free radicals from the environment or from our own body. Unlike vitamin E, vitamin C does not stop the free radical chain in its tracks, but, it is the first line of defense against all types of free radicals.
How the Chain Works
Vitamin A scavenges for free radicals deep inside our cell membranes. When it encounters one, it neutralizes it by accepting the free radical’s electron. However, vitamin A becomes energized and more reactive, much like a free radical. As it makes it way towards the surface of the membrane it encounters vitamin E, which accepts the extra electron from vitamin A. This allows vitamin A to return back to its normal state. Vitamin E, however, is energized by the extra electron it received from vitamin A. Vitamin C, which is present all over our body, reacts with vitamin E, taking the extra electron away, returning vitamin E back to its normal state. Vitamin C, which is hydrophilic, travels through the bloodstream passing the electron between other vitamin C molecules. When they reach the kidneys, vitamin C molecules are filtered out of the bloodstream and eventually out of the body.
How the A E C chain works is still somewhat of a mystery because most studies focus on the relationship between vitamins E and C and tend to minimize the importance of vitamin A. In addition, not much research has been done on the A-E-C chain itself since the 1990’s. More recent studies, however, do indicate that there is a relationship between vitamins A and E but still stress that the relationship between vitamins E and C is more profound. As a result, vitamins E and C tend to receive more attention than vitamin A when it comes to their roles as antioxidants.
Nevertheless, because of this unique relationship between the three vitamins, it’s important that we get our recommended daily doses of vitamins A, E and C. It’s also equally important not to get too much of these vitamins because they can begin to have a negative effect on our bodies. In fact, vitamins E and possibly C may begin to act like pro-oxidants instead of antioxidants when we have too much of them in our body. Check out more about Vitamin A, Vitamin E and Vitamin C.
– By Sewit Haile, MPH
- Rock C, Jacob R, Bowen P. Update on the biological characteristics of the antioxidant micronutrients: vitamin C, vitamin E, and the carotenoids. Journal Of The American Dietetic Association. July 1996;96(7):693-702.
- Niki, Etsuo, et al. “Interaction among vitamin C, vitamin E, and beta-carotene.”The American journal of clinical nutrition 62.6 (1995): 1322S-1326S.
- Palozza, Paola, Soundos Moulla, and Norman I. Krinsky. “Effect of β-carotene and α-tocopherol on radical-initiated peroxidation of microsomes.” Free Radical Biology and Medicine 13.2 (1992): 127-136.
- Edge, R., D. J. McGarvey, and T. G. Truscott. “The carotenoids as anti-oxidants—a review.” Journal of Photochemistry and Photobiology B: Biology41.3 (1997): 189-200.
- Lin, Jennifer, et al. “Vitamins C and E and beta carotene supplementation and cancer risk: a randomized controlled trial.” Journal of the National Cancer Institute 101.1 (2009): 14-23.