It seems as though there is an ever-increasing amount of foods and some supplements that are being touted for their antioxidant properties. So, they must be good for you, right? It is certainly true that we need to include sources of food in the diet that contain plenty of antioxidants to keep us healthy, but what exactly are antioxidants and what do they do?
It may come as little surprise to know that antioxidants are the ‘anti’ to oxidants, stopping oxidants running riot in the body, causing damage to our DNA and other cellular structures, which is the basis for causing cancers and is linked to other chronic, potentially life limiting illnesses. Surely then, we want to eliminate oxidants from our bodies completely to keep us healthy and disease free? Well, not exactly.
Oxidants, also known as reactive oxygen species (ROS) are important cellular signallers, we might be familiar with products that increase nitric oxide, thus promoting increased blood flow and muscle pump. These are part of this ROS family and ROS play important, in fact, essential roles in our bodies’ capacity to signal between cells.
Increased amounts of ROS are found when performing strenuous exercise for this reason and are a normal, healthy part of human metabolism that allows our bodies to respond and adapt to the stresses of training.
The real difficulty comes when we ‘lose control’ of the amount of ROS our body is producing, when the diet is lacking in antioxidants, or under periods of increased exercise or stress caused by our environment (pollution etc) or other lifestyle factors (lack of sleep, use of drugs, excessive alcohol etc). This increase in ROS as a response to different stressors is called oxidative stress and this is what we need to try and avoid or limit in our daily lives.
The main way we can prevent excessive oxidative stress is by providing plenty of antioxidants in the diet, or through using supplements that boost our oxidative defences. The use of supplements is potentially useful when rapidly increasing training volume or output or when we are struggling to recover due to lack of sleep or when on periods of dieting when we are under both exercise and diet-induced stress.
Due to the large number of ROS, our body needs to produce a number of different antioxidants to keep them in check. These include dietary antioxidants such the water soluble vitamin C, fat soluble vitamin E and Beta-Carotene (Vitamin A). These work by interrupting the pathways by which ROS cause cellular damage, there are also other specialised antioxidants such as glutathione, with its precursor l-cysteine being included in some antioxidant supplements, and various enzymes which dispose of ROS and maintain appropriate levels of oxidants in the body.
In order to support our antioxidant defence system, we need to consume a diet with plenty of fruit, vegetables and healthy fats alongside adequate amounts of protein to support the production of the specialist antioxidant enzymes. Antioxidant supplements often contain high amounts of vitamins A, C and E, or precursors to the manufacture of the enzymes that keep ROS in check. However, before overdoing it on antioxidants, it has been suggested that too many antioxidants may reduce performance and inhibit muscle growth as we still need enough ROS to perform their essential signalling roles.
In summary, a balanced diet containing adequate protein, fruit and vegetables and healthy fats should be sufficient to keep oxidative stress under control, however for those under large periods of stress, caused by hard dieting, large training volumes and lack of sleep and often the threat of all three (which would be common amongst dieting athletes), then boosting your antioxidant defences may offer some positive protective effects against oxidative stress.
Paul Rimmer (BSc, MSc, PhD).
