What is an antioxidant?
Antioxidants have recently gained a lot of attention, due to claims that they can make us live longer and healthier lives. If you walk around a supermarket you’ll see all kinds of products, ranging from skin care to whole foods, labelled as being ‘high in antioxidants’. So what do these antioxidants actually do? When the oxygen we breathe is metabolized, reactive oxygen species (ROS) are formed. Under normal conditions these ROS play important roles in our daily functioning, however during times of high environmental stress such as UV or heat exposure, ROS levels increase rapidly and can cause a lot of damage to cells. The process by which ROS exert damage on cells is called oxidative stress. Antioxidants decrease the levels of ROS and thus prevent oxidative stress allowing us to potentially lead longer and healthier lives.
Since maintaining an optimal level of ROS in our bodies is essential to our survival, we have many ways of preventing a rise in ROS levels and subsequent oxidative stress. Two of the main ROS species are superoxide and hydrogen peroxide and two antioxidant enzymes that our bodies produce, superoxide dismutase and catalase break these down. Superoxide dismutase breaks down superoxide into oxygen and hydrogen peroxide. Catalase then further breaks down hydrogen peroxide into water and oxygen. In addition to these antioxidant enzymes, a proper diet also contains antioxidants such as vitamin A, C and E that work independently from the antioxidant enzymes. These antioxidants directly prevent oxidative stress because they can be oxidized by ROS; this in turn reduces ROS to substances that are no longer harmful. For example when vitamin C comes in to contact with hydrogen peroxide, it breaks it down to water whilst forming harmless dehydroascorbic acid, which is the oxidized form of vitamin C.
Most individuals reading this article are likely interested in increasing their cognitive abilities. Antioxidants will not directly increase your cognitive abilities but they are essential for maintaining your cognitive abilities. It has been found that oxidative stress plays a role in many neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s1. Antioxidants thus exert a neuroprotective effect in the brain since they decrease oxidative stress. Maintaining a proper diet with adequate fruits and vegetables is a good strategy in order to preserve your cognitive abilities. However it might also be smart to supplement your diet with the antioxidants resveratrol and pterostilbene.
Resveratrol has recently gained a lot of attention because it is falsely believed to be responsible for the health benefits associated with red wine consumption. However, red wine contains very small amounts of resveratrol. A recent study found that a litre of red wine contains between 0.8-3.2 mg of resveratrol2. The recommended dose of resveratrol is between 150-500 mg, which would translate to about 187 – 625 litres of red wine. Fortunately pure resveratrol is available, and it is a very healthy compound. It not only acts as a direct antioxidant but it also increases the levels of the antioxidant enzymes superoxide dismutase and catalase3, this provides excellent protection against oxidative stress.
If you look at the pterostilbene molecule above and compare it to the resveratrol molecule, then you will notice that the two molecules are nearly the same. The only difference between them is that pterostilbene has two methoxy groups. This increases bioavailability. When pterostilbene is consumed, 80% of it is absorbed whereas only 20% of resveratrol is absorbed4. It has been proposed that the health benefits of blueberries are in part due to their pterostilbene content. However, one gram of blueberries contains between 99-520 ng4 of pterostilbene and the recommended dosage of pterostilbene is between 10-500 mg. This would translate to about 19 – 960 kg of blueberries. Fortunately pure pterostilbene is available and has many of the same benefits as resveratrol with the benefit of increased bioavailability. Pterostilbene in lower dosages (10 mg) seems to have some unique effects on cognition such as an ability to reduce anxiety5. These effects are not seen with higher dosages. Thus it might advantageous to use resveratrol as an antioxidant supplement whilst adding in low doses of pterostilbene to reduce anxiety.
- Andersen JK (July 2004). “Oxidative stress in neurodegeneration: cause or consequence?”. Med. 10 Suppl (7): S18–25.
- Vitaglione, P., Sforza, S., Galaverna, G., Ghidini, C., Caporaso, N., Vescovi, P., Marchelli, R. (2005). Bioavailability of trans-resveratrol from red wine in humans. Molecular Nutrition & Food Research Mol. Nutr. Food Res., 49(5), 495-504.
- Zheng Y, Liu Y, Ge J, Wang X, Liu L, Bu Z, Liu P (2010): Resveratrol protects human lens epithelial cells against H2O2-induced oxidative stress by increasing catalase, SOD-1, and HO-1 expression. 4. Mol Vis, 16:1467-1474.
- Mccormack, D., & Mcfadden, D. (2013). A Review of Pterostilbene Antioxidant Activity and Disease Modification. Oxidative Medicine and Cellular Longevity, 1-15.
- Rahim, M., Rimando, A., Silistreli, K., & El-Alfy, A. (2013). Anxiolytic Action of Pterostilbene: Involvement of Hippocampal ERK Phosphorylation. Planta Med Planta Medica, 79(9), 723-730.