We have all seen social media posts touting the “protective, antioxidant properties of…..[insert food, chemical, drug here]”, but, what are antioxidants and how do dietary antioxidants actually work?
The word antioxidant indicates that it is the opposite of something, an “oxidant.” Everyday cells are exposed to damaging agents both internally (endogenously) and externally (exogenously). Exposure to ultraviolet radiation (as found in sunlight), naturally occurring ionising radiation, drugs, exercise, and cellular metabolism can produce what are known as “reactive oxygen species” or, ROS. ROS are by-products of the metabolism of oxygen that have the capacity to damage parts of cells as well as DNA. Despite the ability of ROS to damage a cell, they are also a natural response to attack pre-cancer cells as well as stimulate cell growth and proliferation.
Therefore, in order to maintain a natural balance between the production and the “mopping-up” of ROS, the cell has developed several mechanisms turn ROS into harmless water and oxygen molecules. This is an “antioxidant action”.
So what about the oft-touted antioxidant action of certain foods? Dietary antioxidants come in the form of Vitamin A, C and E found in certain foods that are broken down to make the antioxidant molecules thus helping maintain the balance between ROS production/removal.
However, studies have begun to show that supplemental sources of these vitamins (i.e. in tablet/liquid form rather than obtained from a fruit, vegetable or oil) can actually upset the balance of ROS production/removal. As mentioned, the generation of ROS are important for certain cellular mechanisms, which is why the cell has generated a response to keep the balance in check.
On the other hand, there are some studies that show vitamin supplements may reduce ROS in people exposed to abnormal levels of ROS, such as in heavy smokers. However, this data still needs further validation and analysis.
What is certain is that absorption of these vitamins at concentrations higher that the Recommended Dietary Allowance (RDA) can result in death in a healthy nourished individual.
Final consideration. If a post appears in your news feed stating “this miraculous food is rich in antioxidants and can cure disease XYZ”, it should be taken with a pinch of salt.An example of this is the blueberry. These were touted a few years ago as a superfood rich in antioxidants. While compounds found in blueberries do have antioxidant action in the lab, when consumed while contained within the blueberry, the compounds are destroyed via normal digestion and therefore rendering the antioxidant potential useless.
So what is the take home message of this post? The first would be that the human body has an amazing ability to monitor and restore the normal balance when it is disturbed. The second message would be that a healthy diet consisting of fruits and vegetables is more than enough of a source of antioxidants.