Oxidative Stress

Free radicals

Free radicals are atoms or groups of atoms with an odd (unpaired) number of electrons that, as the picture above demonstrates, can form as a result of our environment and/or modern lifestyle and diet etc. Once formed, if unchecked, these highly reactive radicals start a number of damaging chain reactions. The most damaging one is the hydroxyl ion (OH-). The main danger comes from the damage they do when they react with important cellular components such as DNA, enzymes involved in metabolism and/or the cell membrane. If cells function poorly it can lead to premature cell death.

To prevent free radical damage the body has a defence system of antioxidants. Antioxidants are molecules which can safely interact with free radicals and terminate the chain reaction before vital molecules are damaged. There are several enzyme systems within the body that scavenge free radicals. The best known are Glutathione and Superoxide dismutase although there are others too.

Oxidative stress is defined as when the formation and concentration of Reactive Oxygen Species (ROS) exceeds the clearance and scavenging activity of the body’s endogenous antioxidant self-defence system. Oxidative stress is positively correlated with ageing and more recent standard Western diets, electromagnetic pollution (EMFs) and stress that can adversely impact us directly and also through disruption of our microbiome and the gut-brain access amongst other knock-on effects.

Disease and Aging

Reactive oxygen species (ROS) are biological products of metabolism that exert both positive and negative effects on the body. ROS include free radicals like the hydroxyl radical (OH-), superoxide anion radical (O2-), nitric oxide (NO-), etc. as well as other oxidants (e.g. hydrogen peroxide (H2O2), peroxynitrite (ONOO-) singlet oxygen (O2), etc.). The primary source of ROS formation occurs via the membrane-bound NADPH oxidase enzyme complex and the electron transport chain (primarily complex 1 and 3) of the mitochondria during aerobic metabolism.

Negative & Positive Effects of ROS

Numerous articles discuss the negative consequences of ROS and their implications on virtually every disease: Immune disorders, such as diabetes mellitus, multiple sclerosis, asthma, rheumatoid arthritis, chronic inflammation, and other fatal diseases such as cardiovascular disease, cancer, neuro-degenerative diseases such as Alzheimer’s disease and Parkinson’s disease as well as ageing (perhaps due to telomere shortening).

However, a more recent understanding of ROS demonstrates that although they may have negative side effects at high levels, they are also important biological signalling molecules that exert therapeutic and protective effects against diseases and play a pivotal role in mediating the benefits of exercise.

Because high levels of ROS are strongly implicated in the progression and pathogenesis of disease, our bodies have the ability to scavenge these ROS after they exert their beneficial signalling effects. For example, the mitochondrial-produced superoxide is dismutated to hydrogen peroxide by superoxide dismutase, which is subsequently reduced to water via the glutathione peroxidase/reductases/NADPH system. The body also uses catalase, glutathione, vitamins A, C, E, etc. to help protect against ROS-induced damage.

The diagram on the right shows why molecular hydrogen can move so much more easily around the body than other common antioxidants.