What causes alcohol flush syndrome in individuals?

Alcohol flush syndrome is primarily caused by a deficiency in aldehyde dehydrogenase (ALDH), an enzyme that is critical in the metabolic pathway for alcohol. When an individual consumes alcohol, it is first converted to acetaldehyde, a toxic compound. Normally, ALDH helps to break down acetaldehyde into a less harmful substance called acetic acid. However, in individuals with a lack of ALDH, acetaldehyde accumulates in the bloodstream following alcohol consumption.

This buildup of acetaldehyde leads to various physiological reactions, including facial flushing, nausea, and increased heart rate. The flush response is particularly common among certain populations, such as those of East Asian descent, where genetic variations can result in lower levels of ALDH.

By understanding this mechanism, it is clear why a lack of aldehyde dehydrogenase is the primary cause of alcohol flush syndrome, leading to the characteristic symptoms experienced by affected individuals.