According to a Finnish research it was found that amino acid, l-cysteine can prevent oral cancers. In the developed countries about 80 % of the cancers occur in the mouth, pharynx and oesophagus. The main causative agent is smoking and alcohol drinking. This results in a strong exposure of the upper digestive tract to acetaldehyde which causes cancer. The research group of Professor Mikko Salaspuro, University of Helsinki and Helsinki University Hospital, Finland, published already in 1990s a hypothesis, that microbes representing normal human digestive tract flora produce locally acetaldehyde from ethanol and that this may expose them for an increased risk of digestive tract cancers.
The hypothesis was strongly supported by Japanese studies showing that digestive tract cancer risk is markedly increased in Japanese drinkers, who have a decreased ability to remove acetaldehyde because of a gene mutation. The cause and effect relationship was subsequently strongly supported by a novel finding of the Finnish research group showing that after a small dose of alcohol Asians with the above mentioned gene mutation have 2-3 times higher concentrations of acetaldehyde in their saliva than those with the normal acetaldehyde removing enzyme.
Most recently, a research group from NIH reported a mechanism that induces DNA-damage in those acetaldehyde concentrations that are found in the saliva after drinking of alcohol. It has been known already for decades that a harmless aminoacid l-cysteine is able to bind effectively acetaldehyde and thereby eliminate its toxicity. On this basis professor Salaspuro and professor Martti Marvola, University of Helsinki, started to develop l-cysteine containing and acetaldehyde eliminating preparations that eventually could be used for the prevention of digestive tract cancers.
We do hope that this will in the future turn out to be a novel method for the prevention of alcohol and tobacco smoking associated oral cancers. However, long term randomised controlled trials are naturally needed before the possible cancer preventive effects can be proved. We are currently planning that type of studies', says Salaspuro. With the saliva carcinogenic acetaldehyde is distributed after swallowing to the pharynx, oesophagus and stomach. Consequently, the effects of l-cysteine may extend to the whole upper digestive tract area.
On the other hand, carcinogenic acetaldehyde can be produced also endogenously by the oral microbes from various foodstuffs with high sugar or carbohydrate content, especially in an achlorhydric stomach. Atrophic gastritis and achlorhydria are well known risk factors of gastric cancer. Therefore, in addition to the chewing gum, also other cysteine containing preparations are under development. The goal is to develop new products releasing slowly cysteine in different parts of the gastrointestinal tract by which acetaldehyde can be eliminated not only in the mouth but also in the stomach and may be also in the large intestine.