Alcohol is a chemical that damages cells in the adult, adolescent, and even the fetus. There are many ways that alcohol can damage cells, but one of the most important is alcohol’s ability to generate reactive oxygen species. Reactive oxygen species (ROS) are formed when oxygen combines with an unpaired electron, which remains in the valence (outermost) shell. The unpaired electron makes the oxygen very unstable, and it is often called a “radical“. Because diatomic oxygen (O2) (the most abundant form of oxygen) has only 6 electrons in each of the outermost shells, it makes oxygen especially susceptible to radical formation (i.e., each oxygen molecule can “steal” 2 electrons from a donor). As long as oxygen is around, radicals can form. Two common ROS that are formed from oxygen are superoxide and hydroxyl radicals (Figure 5.6).
Figure 5.6 Several reactive oxygen species that are generated in cells by alcohol are shown. The most damaging radical is the hydroxyl radical.
Because oxygen radicals are so unstable, they seek to either donate their lone electron or steal another one from some other molecule. Typically oxygen radicals steal an electron from DNA, proteins, and lipids, causing damage to these essential cellular molecules. Eventually, the destruction of DNA, proteins, and lipids causes cell death. Even though ROS are generated as a part of normal life, the body is able to “fix” some of the damage using repair mechanisms. For example, cells also make molecules called antioxidants, which destroy the oxygen radicals. Other antioxidants we get from our diet–vitamins C and E are really good antioxidants. But when alcohol is present, the number of ROS overwhelms the cell’s ability to fix the damage, resulting in permanent damage to the cell.
Learn more about how alcohol generates reactive oxygen species and the cellular damage that follows
The developing fetal brain is extra sensitive to the damage resulting from ROS. The heightened sensitivity is because the brain is constantly forming new brain cells (neurons) by a process called neurogenesis. Also, the brain uses the highest amount of oxygen in the body, making it more susceptible to oxygen-related damage. The alcohol-induced oxidative damage to the neurons leads to the behavioral and cognitive problems prevalent in children with FASD.