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About a decade ago, I began saying that coffee was the number-one killer in America, bigger than cigarettes. This was amidst the explosion of Starbucks and studies sponsored by the coffee industry touting the health benefits of America’s favorite drink. Sounds nutty, right? Now a new study shows that whether coffee kills or helps you depends on your genes.

My Experience

If you’re pursuing a low-carb diet, they tell you to avoid caffeine because it can have a negative effect on your blood sugar. Basically, coffee will tank your blood sugar, causing you to crave sweets. This makes sense, as just based on the prima facie evidence, your local Starbucks is filled with sugary drinks and pastries and not beef jerky and deli meats—meaning that the average American wants something sweet to go with his or her latte.

However, the blood sugar experience isn’t uniform. Take, for example, my wife and me. If I were to indulge in drinking coffee like the average American (3–4 cups a day), or even like some of my brothers, I would be on a blood-sugar roller coaster that would eventually push my weight up 50–100 pounds or more. I also can’t drink coffee or consume any caffeine past 3 p.m., and if I have too much at the wrong times (like when I’m well rested), I get confused and jittery. However, my wife is quite different. Coffee doesn’t do that to her. She can drink it black (rather than the heavily sugared version I would prefer), and nothing happens but a nice, steady rush of energy. It doesn’t make her blood sugar tank—in fact it almost never tanks in any circumstance. She can also down espresso shots at dinner and still get to sleep, and she never gets jittery if she has too much.

The Newly Discovered Caffeine Metabolism “Coffee” Gene

The studies on coffee drinking and health have been all over the board. The ones we tend to hear about are those that seem to imply that drinking the stuff helps you. For example, some studies show improved memory and a lower risk of Alzheimer’s disease. However, then there are those studies, like this one, that show that coffee drinking causes a one-third increased risk of a heart attack.

The authors of the heart attack study above dug a bit deeper to see if there were genetic differences in their study population’s reaction to coffee. Sure enough, they found differences in heart attack risk depending on whether study participants had either a slow or fast metabolizing version of the CYP1A2 gene. Basically, if you have the slow type, your body takes a long time to break down caffeine. That’s me! If I had an espresso shot at dinner, I’d still be up to see the sun rise the next morning! However, if you have the fast-metabolizing version, you get rid of caffeine in your system quickly. That’s my wife, who can have an espresso shot with dinner and still get 7–8 hours of sleep.

The study demonstrated that participants with the different coffee genes had radically different heart attack rates related to coffee consumption. The slow metabolizers, like me, had anywhere from a one-third to a doubling of heart attack risk, depending on how much coffee they drank per day and their age (people under approx. 60 had a higher risk). However, the fast metabolizers had no increase in heart attack risk to some decrease in risk, regardless of age or how much coffee they consumed.

Why Starbucks Is Causing More Morbidity Than Phillip Morris

The risk of the coffee gene extends beyond heart attacks as well. It has also been associated with high blood pressure. People with the slow gene have an increased risk of getting hypertension, while people with the fast version have no increased risk. In a separate study, the same thing happens to whacked-out blood-sugar levels, which increase the risk for diabetes.

So if you have the slow version of this gene, visiting your local Starbucks isn’t all that much different from buying a pack of Marlboros. If you have the fast version, then you should have a frequent-flyer punch card! How can you tell which you are without genetic testing?

Knowing Your Coffee-Gene Status Is Easy

If you’re like me (who has the slow type gene), you can’t drink coffee after a certain time of day or it will keep you up. If you’re like my wife (who has the fast version), you can down a double espresso with dinner and still sleep like a baby.

The upshot? If you have certain genes, avoiding the daily American ritual of a double-shot, skinny Frappuccino may save your life. If you have a different version of the same gene, you should get to know your local barista on a first-name basis!

Chris Centeno, MD is a specialist in regenerative medicine and the new field of Interventional Orthopedics. Centeno pioneered orthopedic stem cell procedures in 2005 and is responsible for a large amount of the published research on stem cell use for orthopedic applications. View Profile