Alcohol flush reaction

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Alcohol flush reaction, (also known as Asian flush, Asian blush, Asian glow and ALDH deficiency) is a condition where the body cannot break down ingested alcohol completely, due to a missense polymorphism that encodes the enzyme, acetaldehyde dehydrogenase (ALDH2) [1], normally responsible for breaking down acetaldehyde, a product of the metabolism of alcohol.[2] Flushing, or blushing, is associated with the erythema (reddening caused by dilation of capillaries) of the face, neck, and shoulder, after consumption of alcohol.

1 Explanations
2 Mitigating the effects
3 Other similar conditions
4 External links

[edit] Explanations

Alcohol, as a toxin, can result in cellular damage after prolonged effects. The first step toward metabolizing alcohol is to convert it to an aldehyde derivative, acetaldehyde. It has been found that 90% of the Pacific Rim Asian population (Chinese, Japanese, Koreans) possess an atypical alcohol dehydrogenase (ADH) known as ADH2*2 that leads to unusually rapid conversion of ethanol to acetaldehyde. This atypical ADH is less expressed in Caucasians, African Americans, Native Americans, and Asian Indian (Agarwal and Goedde, 1992). Since acetaldehyde is more toxic than alcohol, its increased accumulation causes flushing in the human body. Moreover, the normal aldehyde dehydrogenase (ALDH2), synthesized in the liver, oxidizes acetaldehyde into a carboxylic acid, acetic acid.[3] Mutant ALDH2 enzyme (known as ALDH2*2) in 45 to 53 percent of Japanese, Chinese, Korean, Taiwanese, and Vietnamese population, however, is only 8% as effective as the normal, wild-type enzyme (ALDH*1). This mutant allele of ALDH2 is dominant, as it interferes with the formation of a fully functional ALDH2 tetramer [4].

Approximately half of people of Asian descent are considered to be sensitive to alcohol due to this condition.[5] Flushing, after consuming one or two alcoholic beverages, includes a range of symptoms: dizziness, nausea, headaches, an increased pulse, occasional extreme drowsiness, and occasional skin swelling and itchiness. These unpleasant side effects often prevent further drinking that may lead to further inebriation, but the symptoms can lead to misassumption that the people affected are more easily inebriated than others.

[edit] Mitigating the effects

Because this syndrome is a result of DNA mutation, there is no treatment for the Asian Flush. However, much anecdotal evidence suggests that consumption of heartburn medicine containing Famotidine (such as Pepcid AC) may be able to reduce the symptoms of Asian Flush if taken an hour before drinking.^{[citation needed]}

It is not known why famotidine may in some cases, but not all, help reduce the symptoms of the alcohol flush reaction. Alcohol is known to irritate the lining of the stomach and increase production of gastric acid. While famotidine functions by reducing gastric acid production in the stomach, it may have an additional (unknown) side effect of inhibiting alcohol dehydrogenase, slowing metabolism of alcohol to acetaldehyde, allowing the poorly functional ALDH2 to metabolize acetaldehyde to vinegar. Because inhibiting alcohol oxidation increases alcohol in the blood, however, people may be more easily inebriated.[6]

Although many people with this condition view it as a lifetime inconvenience, some people have suggested that they can condition their body to be more tolerant of alcohol with repeated, moderate drinking, perhaps increasing the concentration of ALDH2 to metabolize acetaldehyde. Unfortunately, acetaldehyde is a known carcinogen; recent research suggests that Alcohol flush-afflicted individuals consuming alcohol continually may be at a higher risk for alcohol-related diseases, such as liver and esophageal cancers and digestive tract cancer.[7]

Individuals who experience the alcohol flushing reaction may be less prone to alcoholism. In fact, a leading treatment for alcoholism, Antabuse, works by inhibiting acetaldehyde dehydrogenase, causing a five to ten-fold increase in the concentration of acetaldehyde in the body. The resulting irritating flushing reaction is intended to discourage alcoholics from drinking.[8] [9]

[edit] Other similar conditions

Gin blossoms -- a longterm symptom of alcohol abuse caused by ruptured capillaries in the face, particularly the nose.
Degreaser's flush -- a flushing condition arising from consuming alcohol shortly before or during inhalation of trichloroethylene (TCE), an organic solvent with suspected carcinogenic properties.