I don't need a genetic test to know that I have an inefficient gene when it comes to metabolizing alcohol. My beet red face and green nose are dead giveaways that I have a variant of aldehyde dehydrogenase that contributes to the classic 'Asian flush'. I've never been a big coffee drinker and made the mistake of trying my first cup of Peet's coffee after 5pm. Around 3am, I was still staring at the ceiling and listening to my heart beat, wondering if Peet's coffee is too potent. New research makes me wonder if I'm also more sensitive to caffeine because of my genetic makeup.A study, published today in PLoS Genetics, found two genes in which variation was linked to caffeine intake. The researchers, from the National Cancer Institute, Harvard School of Public Health, Brigham and Women's Hospital, and the University of North Carolina at Chapel Hill, summarized: Caffeine is the most widely consumed psychoactive substance in the world. Although demographic and social factors have been linked to habitual caffeine consumption, twin studies report a large heritable component. Through a comprehensive search of the human genome involving over 40,000 participants, we discovered two loci associated with habitual caffeine consumption: the first near AHR and the second between CYP1A1 and CYP1A2. Both the AHR and CYP1A2 genes are biologically plausible candidates, as CYP1A2 metabolizes caffeine and AHR regulates CYP1A2. Now it may be a bit reductionistic to attribute habits like coffee intake to a liver enzyme - CYP1A2 codes for a protein that metabolizes a variety of drugs in the liver - but the results of this study may help us to better understand and possibly predict our reactions to caffeine. The gene variant responsible for the 'Asian flush', also in the liver, has been associated with increased risk of esophageal cancer. Maybe a better understanding of our genetic determinants of dietary and lifestyle behaviors can help inform choices that promote health and wellness. Source: www.sfgate.com/cgi-bin/blogs/wchung/detail?entry_id=86