More than half of American adults drink coffee daily. But how does that caffeine affect us, biologically? It depends on genetics.
Is morning just not morning without a steaming mug of coffee in your hand? You’re not alone, as a little more than half of American adults drink coffee daily, for the taste, the aroma, the pick-me-up or all of the above. I suspect that number’s even higher in Seattle. As an added bonus, moderate coffee consumption is linked to a number of health benefits, including reduced risk of developing type 2 diabetes. But for some people, the caffeine in even moderate amounts of coffee could have a downside.
The safe caffeine limit for healthy nonpregnant adults is 400 milligrams (mg) per day, the amount in four average 8-ounce cups of brewed coffee. The average caffeine intake in this country is about 180 mg per day, but those averages are just that — average. Some people get less caffeine than that, and others get more, sometimes much more, because not all coffee is “average.”
For example, a 12-ounce medium roast at Starbucks has about 235 mg. Get a refill and you’ve exceeded your limit. Then there’s the growing trend of super-high-octane coffee, with brands like Black Insomnia and Death Wish competing for the title of “world’s strongest coffee” and clocking in at about 700 mg of caffeine for a 12-ounce cup. While that’s not optimal for anyone, for some people it might be risky — the collision of genetic differences in how we metabolize caffeine with the latest generation of high-caffeine beverages may have unintended consequences.
How caffeine makes you feel is partly due to your tolerance level, but it’s largely due to genetics. Of greatest concern is one gene — CYP1A2 — that alters how caffeine affects us, but in ways we don’t actually feel. Depending on which version of the CYP1A2 gene you inherited, you metabolize (break down) caffeine slow or fast….