What's Your Poison?

Awhile ago, I linked to an article about acetaldehyde (pictured), which is the toxic ethanol metabolite that gives people a hangover when they drink too much. This week, I read an article in the New Scientist about acetaldehyde. It turns out that acetaldehyde is found in more substances than you probably ever thought possible. Not only is it a metabolite of ethanol breakdown by the liver, but it is also found in tobacco, vehicle exhaust fumes, coffee, and ripe fruits; it is often used to create a fruity flavor in yogurt; and it is produced by certain mouth bacteria.

For many years, acetaldehyde was thought to be a harmless metabolite in the breakdown of ethanol, but in the 1980s, alcohol researcher, Victor Preedy of King's College London, found that acetaldehyde is a potent muscle poison, roughly 30 times more toxic than ethanol itself. It not only damages muscles but it also causes serious long-term damage to all internal organs, including the liver, heart and brain. It is thought to be at least partially responsible for the rising incidence of cancer and liver disease as well as possibly being linked to Alzheimer's disease.

It is becoming clear that almost any exposure to acetaldehyde can cause serious damage. Acetaldehyde forms covalent bonds with amino acids in proteins, giving rise to a stable compound known as an adduct. These adducts cause irreversible damage by altering the protein's structure and function. After a drinking bout, a large number of adducts are created in the internal organs and these altered proteins can hang around for longer than 24 hours after all acetaldehyde has disappeared from the body.

Acetaldehyde also attacks the DNA in much the same way that it interacts with proteins. The resulting adducts disrupt DNA's structure and function, giving rise to mutations and chromosomal abnormalities. Additionally, the immune system reacts to these adducts as being foreign entities, thereby causing inflammation to occur. This inflammatory response has been associated with a variety of diseases, including rheumatoid arthritis, heart attacks, Alzheimer's disease and cancer.

Among smokers, the risk of oral cancer is 7- to 10-times greater than in those who have never smoked. However, the effects of acetaldehyde exposure are synergistic such that people who both smoke and drink have a 150-fold increase in oral cancer compared to those who abstain from both.

As if that isn't bad enough, acetaldehyde is also produced by certain bacteria that colonize the mouth. As a result, people with poor dental hygiene are at an increased risk for oral cancers. But worst, acetaldehyde can also be found in foods that result from fermentation such as pickles, bread and cheeses. It also occurs naturally in coffee and ripe fruits.

So what is being done to combat all this acetaldehyde? One research group in Helsinki, Finland, is developing a chewing gum that can soak up acetaldehyde. This gum contains the amino acid, L-cysteine, which binds to acetaldehyde, converting it into a harmless compound, thereby removing it from the saliva. This gum is being commercialized by the Finnish company, Biohit.

Mouthwashes can also be used to soak up acetaldehyde. For example, the antiseptic, chlorhexidine, has been shown to reduce the numbers of acetaldehyde-producing bacteria in the mouth by 40% after three days' use.

Another possible solution is altering the bacterial make-up in the mouth and intestines through the use of prebiotics and probiotics. Lactulose is a harmless and indigestible sugar that also appears to inhibit bacterial acetaldehyde production by making the colon more acidic. Ingesting a dose of living bacteria that don't produce acetaldehyde could also help.

Unfortunately, none of these interventions prevent cancer, so there is no substitute for a healthy lifestyle.

Cited story; What's Your Poison? by Lisa Melton. New Scientist pp. 30-33, 193:2590 (February 10-16 2007).

Image source: Wikipedia.