Caffeine — if you’re like most people, you can’t start the day without it, whether you get it from coffee, soda, or even your toothpaste. The average American consumes 300 mg of caffeine per day, according to the FDA. That’s more than three regular cups of coffee — or the equivalent of one venti Caffe Americano at Starbucks.

But is all this caffeine healthy — or harmful? Studies can’t seem to reach a consensus. Some show that moderate caffeine intake can provide multiple benefits, while others claim that just drinking one or two cups of coffee a day can be harmful to your health. Which should you believe? The answer may not be so black and white.

The health benefits of caffeine

A growing body of research suggests that caffeine can help protect brain cells and lower the risk of certain neurological conditions, such as dementia, stroke, and Parkinson’s disease. Caffeine has also been shown to relieve migraines and tension headaches.

Coffee in particular may help reduce the risk of gallstones, heart conditions, and certain cancers. A 2015 study found that drinking three cups of coffee a day reduced the risk of liver cancer by more than 50 percent. A separate study revealed that people who drank more than four cups of coffee daily cut their risk of mouth and throat cancer in half.

Caffeine may have mental health benefits as well. A study from the Harvard School of Public Health showed an association between caffeine consumption and a lower risk of suicide.

Negative effects of caffeine

However, caffeine has also been associated with several negative health effects, including anxiety, upset stomach and muscle tremors. In some people, caffeine can trigger migraines rather than relieve them.

One study found that women who consumed between 31 and 250 mg of caffeine every day had an increased risk of fibrocystic breast disease. Caffeine may worsen certain menopause symptoms, including night sweats and hot flashes. It may also contribute to skin aging by impairing the wound healing process process and inhibiting the production of collagen.

Some studies have demonstrated a negative association between caffeine and cardiovascular health. One study found that heavy coffee drinkers had four times the risk of having a heart attack.

Caffeine and genetics

How can separate studies show that caffeine is both good for and bad for the heart? The answer may have something to do with genetics. A 2014 study identified six genetic variants that influence how people respond to caffeine. In particular, caffeine is metabolized in the liver by an enzyme known as CYP1A2. Variants in this gene determine how quickly an individual metabolizes caffeine, meaning someone is either a fast caffeine metabolizer or a slow caffeine metabolizer.

Fast caffeine metabolizers — those who inherit two copies of the “fast” variant — generally metabolize caffeine four times more quickly than individuals who have one or more copies of the “slow” variant. If you can drink a lot of caffeine without feeling much of an effect — or you can drink coffee right before bed and have no difficulty falling asleep — you are likely a fast caffeine metabolizer, and may benefit from the antioxidants, polyphenols, and other healthful compounds in coffee.

Slow caffeine metabolizers, however, feel the effects of caffeine more strongly. They’re also more susceptible to its negative consequences, such as high blood pressure and and increased risk of heart attack. This may be because caffeine remains in the bloodstream longer, giving it time to disrupt normal heart rhythms and trigger heart attacks. Given the potential health risks, slow caffeine metabolizers should reduce caffeine consumption to one cup of coffee or the equivalent per day.

Certain lifestyle factors can also influence your ability to metabolize caffeine, including whether you smoke or take hormonal birth control.

Genetic testing can reveal whether you are a fast or a slow caffeine metabolizer. Request a consultation with a Vivaliti DNA health coach to learn how obtaining your personalized genetic blueprint can help you make smarter choices about your health every day!