What Is the ALDH2 Gene?
The ALDH2 gene produces an enzyme that helps break down acetaldehyde, a toxic substance created when alcohol is metabolized. When this gene is inactive, the body cannot efficiently process acetaldehyde, causing symptoms such as flushing, nausea, and rapid heartbeat after drinking alcohol.
A Trait Unique to East Asians
While this gene variant is extremely rare in Western populations, about 30–50% of East Asians, especially Japanese, Chinese, and Koreans, carry the inactive form. Among the Japanese, it’s estimated that around 40% are affected.
Why Did This Mutation Survive?
Scientists have several theories:
- Rice Cultivation and Fermentation
In ancient times, fermented foods and drinks were a key part of the East Asian diet. Those who became ill after drinking alcohol may have avoided excessive alcohol consumption, which helped preserve their health in a microbial-rich environment. - Survival Advantage Against Pathogens
A build-up of acetaldehyde makes people feel sick, which might have helped reduce alcohol consumption during disease outbreaks, lowering infection risk. - Random Genetic Drift
Another possibility is that the mutation spread simply by chance over generations in isolated populations.
Health Impacts of the Inactive ALDH2 Gene
While it may have had evolutionary benefits, this gene variant is a double-edged sword today:
- Increased Cancer Risk
Acetaldehyde is classified as a Group 1 carcinogen. People with inactive ALDH2 are more susceptible to esophageal and head and neck cancers if they consume alcohol regularly. - Cardiovascular Effects
Some research suggests a link between ALDH2 inactivity and a higher risk of heart disease and high blood pressure. - Medication Sensitivity
The gene can affect how certain medications are processed, especially those related to anesthesia and cardiovascular treatment.
A Gene Worth Knowing
If you’ve ever felt your face flush or felt unwell after a small amount of alcohol, you might be one of the many East Asians with this genetic trait. Knowing your ALDH2 status can help you make informed choices about drinking, diet, and health management.
Final Thought:
This tiny gene mutation, passed down through generations, not only shapes our reactions to alcohol but also tells a fascinating story about adaptation and health. Understanding your genes is one step toward a healthier life.