May 9/Chapel Hill, N.C./Star -- Some 90% of the world’s population consumes caffeine in one form or another, but what sets apart a coffee guzzler from their cup-a-day compatriots comes down to two genes, according to a new study.

Researchers at Harvard School of Public Health, Brigham and Women’s Hospital and the University of North Carolina at Chapel Hill looked at five population-based studies that tracked the caffeine consumption of 47,000 people, over 17 years, by charting their intake of coffee, tea, soda and chocolate.

Coffee is the caffeinated beverage of choice for people in North America, being favored by 80% of the population. However, the component that drove people to consume vast amounts of this bitter beverage was previously unknown to scientists.

“Many factors are linked to caffeine intake: social, smoking, preference, taste,” said Dr. Marilyn Cornelis, the lead author of the study. “From our study we are able to say that it is the caffeine component that is really driving our behavioral propensity toward this beverage, otherwise we would have seen genes associated with bitterness show up,” Cornelis told the Star.

Cornelis and her team found that those who consumed the most caffeine in the five studies examined shared a genetic trait -- the CYP1A2 and AHR genes.

CYP1A2 has long been associated with the metabolism of caffeine, and AHR acts as a catalyst speeding up the rate the caffeine is metabolized in the body.

People who had both of the genes consumed 40mg more caffeine a day, equivalent to a can of pop, than those who had neither.

Some 60% of the participants had at least one of the genes.

Because both genes play a role in metabolizing caffeine in the body, Cornelis hypothesizes that those with both genes consume more caffeine to help maintain levels of the stimulant in their body, levels that drop faster than in those with one or neither of the genes.

“Because it [AHR] plays a role on the catalyzing, it has a direct response on the levels of caffeine in the body, meaning people have to have caffeine more frequently to keep it the body,” she said.

This is the first time a genome-wide association study -- a technique where most of the genes of a particular group are compared to find genetic variations and associated these variations with different traits -- has been applied to identify genes not associated with a disease.

Other studies have looked at the genes linked to tobacco and nicotine addiction, but Cornelis and her team studied the habitual use of caffeine, not people who were hooked on their morning brew.

 

From the May 11, 2011, Prepared Foods' Daily News.