The alcohol flush reaction is characterized by an intense red flushing of the face, neck and shoulders. It is due to the temporary expansion of tiny blood vessels in the face and neck, and is a sign of alcohol intolerance.
The majority of the alcohol that we drink (aka ethanol) is broken down in a two-step process involving two enzymes. Alcohol dehydrogenase (ADH) converts ethanol to acetaldehyde in the first step of alcohol metabolism. Acetaldehyde is usually only short-lived and is converted to acetate by aldehyde dehydrogenase (ALDH). Acetate is easily broken down to carbon dioxide and water.
The alcohol flush reaction is linked to a genetic variant of the ALDH2 gene. This variant also increases the risk of esophageal cancer and is found in approximately 30% of Asians, but is absent in Caucasians.
To test for additional variants linked to alcohol intolerance, please order the DNA Alcohol Intolerance test.
The ALDH2 gene gives instructions to make the ALDH enzyme responsible for breaking down acetaldehyde to acetate. Individuals with the ALDH2 variant produce an enzyme that has lower activity resulting in significantly higher acetaldehyde levels after a drink. The elevated acetaldehyde levels are responsible for the symptoms of alcohol flush.
- rs671 in the ALDH2 gene
The accumulation of toxic acetaldehyde is a major contributing factor to the risk of esophageal cancer. Studies in Asian populations show that carrying one variant of the ALDH2 gene (heterozygous G/A genotype) is the strongest risk factor linked to esophageal cancer. Individuals who do not drink, or are light drinkers, with the G/A genotype have an approximately 4x increased risk of esophageal cancer, while heavy drinkers with this genotype have greater than a 6x increased risk (with many studies indicating a higher than 10x increased risk).
- Facial flushing
- Increased heart rate
- Severe hangovers
Long term effects of continued alcohol consumption include
- Increased risk of esophageal cancer
- Cardiovascular problems
- Memory loss
- Mental confusion
- Psychological issues
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