There are two basic causes of what someone might call alcohol intolerance, one more common but less accurate than the other. The not so accurate description would be an allergic reaction to components in alcoholic drinks. In this case, it is not the alcohol (ethanol) in alcoholic drinks that is causing the reaction, but instead other components that make up the drink, such as someone with an allergy to barley, who would then be allergic to most beers.
I have a friend who is allergic to something in beer, who went out drinking one night with the guys. For some reason, he felt it would be a good idea to not mention that he was allergic to beer, and instead accepted our offers of some hoppy goodness. Within a few minutes, his face had turned red, and his throat was swelling up, restricting his ability to breathe. Fortunately, after some freaking on everyone’s part, he turned out ok, and was subsequently mocked for not mentioning that minor little detail. But since he was quite fine drinking various other types of alcohol, such as rum and vodka, he does not have a true alcohol intolerance.
A true alcohol intolerance refers to someone’s liver being unable to fully break down the alcohol in the blood stream. Metabolizing of the alcohol by the enzymes in the liver occur in two steps. First, the alcohol is broken down into acetaldehyde, by an enzyme called alcohol dehydrogenase (ADH). Next, the acetaldehyde is broken down into acetic acid, which passes into the blood stream and can be metabolized by the rest of the body. This is done by another group of enzymes, aldehyde dehydrogenases (ALDH).
Some of the symptoms of a hangover are caused by the effect of unmetabolized acetaldehyde in the blood stream, which occurs when the liver’s ability to process the alcohol is overloaded.
However, some people have a genetic quirk which causes their liver to be unable to effectively process alcohol from the bloodstream. Most often, this is caused by the liver having a mutant form of one of the ALDH enzymes, which is ineffectual at changing the acetaldehyde into acetic acid. If someone with this genetic condition consumes alcohol, the levels of acetaldehyde can quickly build up in the blood stream, which can cause hangover-like symptoms, such as flushing of the face, heartburn, nausea, and vomiting.
This condition is most prevalent in those of Eastern Asian descent, with up to 41 % of Japanese people having it, and up to 30 % of Taiwanese. Again, this is not an allergy, as allergies are caused by the immune system’s response to something it deems as unwanted. This is not the case.
Alcohol intolerance can also be artificially induced, through the use of a drug known as disulfiram. An extension of western medicine’s belief that there is a pharmaceutical solution to every problem, this drug is used to treat chronic alcoholism. Mind you, I first learned of the existence of this drug from a newspaper advice column, where a reader was writing in for advice on what to do about someone their cared about. Said person was a recovering alcoholic, who was being treated with disulfiram, but had admitted that on occasion they went off the drug, and instead pounded back a bottle of wine or two. Truly, you can’t prescribe a fix to everything.
Disulfiram works by inhibiting the acetaldehyde to acetic acid reaction of the ALDH. People who are being treated by disulfiram, and who decide to partake in alcohol anyways, are hit with severe hangover-like effects within 15 – 30 minutes of the consumption of alcohol. Classical conditioning at its finest.
As well as having a genetic pre-disposition, and the use of drugs to induce the effect, some people can gain an alcohol intolerance-like condition due to the onset of other conditions. Hodgkin’s lymphoma can cause acute pain as a reaction to alcohol use, and the use of alcohol can intensity the physical effects of menopause.
Li, James. "Alcohol allergy: Is there such a thing?." MayoClinic.com. 12 March 2008. <www.mayoclinic.com/health/alcohol-allergy/AN00818> (30 Oct, 2008).
CMPMedica Australia. "LIVER AND ALCOHOL BREAKDOWN," myDr.com.au. 30 March 2007. <http://www.mydr.com.au/default.asp?article=4127> (30 Oct, 2008).
Wikipedia. "Disulfiram," Wikipedia, the free encylopedia. 29 September 2008. <en.wikipedia.org/wiki/Disulfiram> (30 Oct, 2008).
Wikipedia. "Aldehyde dehydrogenase," Wikipedia, the free encylopedia. 28 October 2008. <en.wikipedia.org/wiki/Aldehyde_dehydrogenase> (30 Oct, 2008).
foodreactions.org. "Alcohol Intolerance & Allergy Like Reactions," foodreactions.org. 2005. <www.foodreactions.org/intolerance/alcohol/index.html> (30 Oct, 2008).
Russell, June. "Alcohol - Menopause," June Russell's Health Facts. 12 June 2003. <www.jrussellshealth.org/alcmeno.html> (30 Oct, 2008.)