Researchers at the University of Helsinki and the University of Eastern Finland completed a study which found that the amino acid L-cysteine can reduce the effect of hangover symptoms such as nausea, headaches and anxiety caused by alcohol consumption.
During the research sessions, the study’s participants gathered in the convention room of a hotel on Friday nights to drink a mixed punch of cranberry juice and the traditional Finnish spirit Koskenkorva over the course of three hours, with each drink containing an alcohol volume of about 10 percent.
The alcohol was served to the subjects at a rate of 1.5 grams per kilogram of body weight. In practice, this means that a participant weighing 75 kilograms would consume nine servings of the alcoholic mixed drink.
"There were clearly intoxicated people, but no-one was falling down drunk," University of Helsinki researcher Markus Metsälä recalls.
In addition to drinking, the subjects were also asked to ingest either a placebo, a 600mg L-cysteine tablet, or a 1,200 mg L-cysteine tablet, but were not told which pill they had received.
Each session ended at 10:30 pm, after which the subjects were asked to rest in their hotel room. The research session continued the following morning with a self-assessment questionnaire of each participant’s state of mind between 8 am and 9 am, asking if the subjects were experiencing headaches, nausea, stress, or anxiety.
The results of the study found that the 1,200 mg dose of amino acid L-cysteine helped to reduce alcohol-related nausea and headache, while the 600 mg tablet helped to ease stress and anxiety.
The tablets also reduced participants’ desire to consume alcohol again the following day, the study found, which the researchers say may help to curb alcohol addiction.
Differences in alcohol tolerance caused research challenges
The study sought experienced drinkers to take part in the research, Metsälä says, but some participants became so unwell during the sessions that they had to leave the study.
Other participants, on the other hand, were not so badly affected, and “over-experienced” drinkers also became a problem in the research, as they did not report hangover symptoms regardless of whether they ingested the amino acid supplement or not.
"Some were not able to drink enough and the test results are therefore not comparable for them. Some subjects, on the other hand, did not have the patience to stop drinking when the study's official drink sessions came to an end, but instead continued to drink more at the hotel bar. They also had to be excluded from the study," Metsälä says.
According to the researchers, this was the first study of its kind worldwide in which an amino acid such as L-cysteine has been found to reduce hangover symptoms, which are largely due to a person’s level of intoxication.
Ethanol is broken down in the body into acetaldehyde, which not only causes a large proportion of hangover symptoms, but is also a carcinogen. When L-cysteine is ingested at the same time as alcohol, the concentration of acetaldehyde is reduced, and the hangover symptoms experienced by the subjects are also therefore reduced.
Metsälä says the research result can be of significant public health and economic benefit if the harm caused by a hangover can be reduced. On the other hand, once a hangover cure is found, people may be encouraged to drink even more.
"This is a double-edged sword," Metsälä says.
The study was funded by the Finnish cat food company Catapult Cat, which sells L-cysteine vitamin tablets, and the article written by the research team was published in University of Oxford’s Alcohol and Alcoholism journal.