It turns out, it's a mix of genetics and lifestyle factors. When you drink coffee, it travels through your stomach, into your bloodstream where it circulates through the body until it lands in the liver to be metabolized.
"Exciting research has found that genetics play a role in how we metabolize caffeine, and some genes can even predict if you are more likely to crave caffeine," Dr. Will Cole, a nutritionist and functional medicine expert, told me.
Cardiologist Dr. Joel Kahn mirrored this idea, adding that not everyone is lucky enough to process caffeine quickly.
"Half of coffee drinkers are slow metabolizers, and three to four cups of coffee or more can raise blood pressure and even the risk of a heart attack," he said.
Hormone expert and author Dr. Sara Gottfried can attest: "I have a gene variant that codes for the enzyme CYP1A2 that makes me metabolize caffeine slowly, so a cup of coffee in the morning makes me stressed, jittery, and bitchy," she explained. "People like me have a greater risk of heart disease when we drink coffee, whereas those who metabolize caffeine quickly receive a longevity benefit from coffee. People without my gene variant don't know what all the fuss is about and drink espresso after dinner."
Lifestyle factors like diet and medications also play a role. Alcohol slows down your ability to absorb coffee while certain meats and vegetables like broccoli, cauliflower, and cabbage speeds up your caffeine metabolism. And medications like birth control actually make you metabolize your cup of joe at one-third of the rate you would otherwise.
The more coffee you drink, the better able you are to tolerate its effects, so you can bet I'm ringing in today's holiday with many, many mugs filled to the brim.