When consuming wine, some individuals experience facial flushing, a common response where the face becomes warm and red. This reaction, often with other symptoms, indicates a heightened sensitivity to alcohol. Understanding how the body processes alcohol explains this phenomenon.
The Body’s Alcohol Processing
The body processes ethanol, the alcohol in wine, through a two-step metabolic pathway primarily in the liver. First, alcohol dehydrogenase (ADH) converts ethanol into acetaldehyde, beginning detoxification. Then, aldehyde dehydrogenase (ALDH) metabolizes acetaldehyde into acetate, a less harmful substance the body eliminates. This sequential breakdown efficiently processes toxic byproducts.
The Key Culprit: Acetaldehyde
Acetaldehyde, a toxic byproduct of alcohol metabolism, is the primary cause of facial flushing. When it accumulates, it triggers physiological responses. This compound causes blood vessels to expand (vasodilation), leading to the visible redness and warmth of flushing. Acetaldehyde also induces histamine release, a chemical involved in allergic reactions, further widening blood vessels and causing skin discoloration.
Genetic Predisposition to Flushing
Alcohol flushing varies significantly among individuals due to genetic differences in alcohol metabolism. A common genetic variation affects the aldehyde dehydrogenase 2 (ALDH2) enzyme, making it less efficient at breaking down acetaldehyde. This deficiency causes a rapid buildup of acetaldehyde after alcohol consumption, intensifying the flushing response. Approximately 30% to 50% of people of East Asian descent, including Chinese, Japanese, and Koreans, carry this genetic variant (ALDH22). While most prevalent there, this variation can affect individuals from other ethnic backgrounds.
Other Wine Components and Their Role
Beyond alcohol and acetaldehyde, other natural wine components can contribute to flushing or similar reactions. Histamines, present in fermented foods and wine, can cause flushing, headaches, and nasal congestion in those with histamine intolerance. Red wine often has higher histamine levels than white wine. Sulfites, used as preservatives and naturally produced during fermentation, can trigger reactions in some people, though true sulfite allergies are rare. Tyramine, another natural compound in wine, can also affect blood vessels and contribute to headaches and flushing.
Health Implications of Alcohol Flushing
Alcohol flushing, especially in individuals with ALDH2 deficiency, signals broader health implications. Acetaldehyde accumulation, a recognized carcinogen, increases the risk of certain cancers, even with moderate alcohol consumption. Studies show an elevated risk of esophageal cancer (squamous cell carcinoma) in ALDH2-deficient individuals who drink alcohol. This heightened risk is due to acetaldehyde’s ability to damage DNA and proteins at the cellular level. Thus, facial flushing serves as a visible warning that the body struggles to process alcohol’s toxic byproducts.