Alcohol consumption is an integral part of the Japanese business culture. Hangovers, however, can have substantial economic drawbacks. A recent study that examines hangovers and genetics among Japanese workers has found that the toxicity of acetaldehyde - the first product of alcohol metabolism - leads to hangovers in individuals with a particular genotype.
Results are published in the July issue of Alcoholism: Clinical & Experimental Research.
"Many Japanese love the idea of group harmony," said Masako Yokoyama of the Mitsukoshi Health and Welfare Foundation and corresponding author for the study. "Going out drinking with various colleagues after work is an essential element of Japanese business society. It is socially acceptable to get fairly drunk on such occasions."
Hiromasa Ishii, president of the Japanese Medical Society of Alcohol Studies and Drug Dependence and Professor Emeritus at KEIO University in Tokyo, concurs. "Drinking alcoholic beverages with working colleagues after a customary 10-hour day at the office is an important part of business society in Japan, despite the fact that 40 to 45 percent of the Japanese people possess inactive ALDH2," he said.
Aldehyde dehydrogenase (ALDH) is a key enzyme in the elimination of alcohol-induced acetaldehyde, which is a toxic compound. If the ALDH enzyme is normal, then acetaldehyde is metabolized very quickly. If it is not, people can experience cardiovascular complications, drowsiness, nausea, asthma and facial flushing. Many East Asians who have a mutant allele called ALDH2*2 also have inactive ALDH2, which usually inhibits them from heavy drinking because of the unpleasant consequences. However, an increasing number of Japanese who have inactive ALDH2 are also heavy drinkers.
Both Yokoyama and Ishii believe that, despite the initial inhibitory effects that a genetic mutation of ALDH can have on alcohol consumption, tolerance to the negative effects of alcohol and acetaldehyde may nonetheless develop if heavy drinking continues.
"Understanding the inhibitory effects of ALDH2 on drinking is incomplete," said Yokoyama, "however, we know that 26 percent of heavy drinkers among urban working men and 12 percent of alcoholics in Japan have inactive heterozygous ALDH2. It would appear that alcohol flushing diminishes in intensity in individuals with long or frequent drinking histories, suggesting the development of tolerance to acetaldehydemia."