If you drink a bit more coffee or tea than most people you know, scientists say it may be thanks to your DNA.
Ah, caffeine. It wakes you up in the morning, helps you get your work done throughout the day and, after a long night, may be the only thing that can get you through the next day. Although it occurs naturally in coffee and cocoa beans, tea leaves and the kola nuts used to flavor some cola beverages, and is safe for most people to consume in moderation, caffeine is still considered a drug.
Caffeine is classified as a drug because of the stimulating effect it has on your central nervous system. It energizes your brain. Decades of research have shown that caffeine is basically a safe drug for most people. Like many drugs, however, caffeine comes with potential side effects, especially at higher doses. These can include anxiety, headaches, dizziness, trembling, and insomnia. Caffeine is a diuretic, which means it causes you to urinate more often. Although caffeine is not stored in your body, you may continue to feel its stimulating effects for six hours or more after drinking your last cup of coffee, tea or cola for the day. If you consume caffeine on a regular basis, you may build up some resistance to it and need more to get the same energizing effect. That means caffeine is somewhat addictive.
Now scientists have discovered that the need to consume more caffeine may also be in your genes. Scientific studies performed at the National Institutes of Health, Harvard University, and other research centers, found that people who carry specific versions of two genes that direct the breakdown of chemicals by the liver will crave and consume more caffeine than those who do not posses those gene variations. With this understanding, researchers can now study both the positive and negative effects of caffeine in a more focused way.
If you cut back or stop consuming caffeine, you may experience withdrawal symptoms such as headaches, fatigue, irritability, nausea, and even depression. The symptoms can be so severe that experts from American University and Johns Hopkins University School of Medicine have proposed including symptoms of caffeine withdrawal in future revisions of the American Psychiatric Association's Diagnostic and Statistical Manual (DSM), which is used to diagnose psychiatric conditions and mental illness. The DSM currently recognizes cocaine, opioid, and nicotine addiction and withdrawal symptoms to validate diagnosis and treatment. If caffeine withdrawal is added to this list, you may find it easier to get help if caffeine is causing problems in your life and you're trying to break the habit.
Sources:
Cornelis MC, Monda KL, YuK, Paynter N, Assato EM, et al. "Genome-Wide Meta-Analysis Identifies Regions on 7p21 (AHR) and 15q24 (CYP1A2) As Determinants of Habitual Caffeine Consumption." PloS Genet 7(4): e1002033:10.1371/journal.pgen.1002033. Web 19 Aug 2011
http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1002033
Juliano, LM and Griffiths, RR; "A Critical Review of Caffeine Withdrawal" Psychopharmacology. 2004 176:1-29 Web 19 Aug 2011
http://neuroscience.jhu.edu/griffiths%20papers/CaffwdReview.2004.pdf
