The other day a patient came to see me concerned that every time he drank coffee, his heart seemed to twitch. "Is this cardiac twitch a sign of heart disease?" he asked. A doctor himself, he pointed to a study done in Zurich that suggested that drinking the equivalent of two cups of coffee reduced the body's ability to boost blood flow to the heart muscle in response to exercise, and that this caffeine effect was stronger at high altitudes. That got me a bit worried myself. After all, I'm a bit of a coffee snob and fancy myself an amateur barista.
The most widely used drug in the world.
The main active ingredient in coffee is caffeine. Caffeine is a plant alkaloid that occurs naturally in coffee, tea, guarana, and cola nuts. It's considered the most widely used drug in the world. The good news is that caffeine improves lung function, helps glucose metabolism in the gut, aids athletic performance, and is used in medications for migraines as well as some chemotherapy drugs. Many carbonated drinks also contain caffeine and when caffeine is present, manufacturers automatically increase sugar content, as caffeine dulls sugar taste receptors. This increased sugar is what makes soda especially bad for you.
People metabolizes caffeine at different speeds.
It turns out that your "cardiac twitch" is related to your caffeine metabolism—slow metabolizers of caffeine have a higher risk of heart attacks if they drink more than two cups of coffee per day; however, fast metabolizers have a reduced risk of a heart attack if they have at least a cup of coffee a day. I suggested that I run some genetic tests on my patient (and while I was at it, I thought I'd test myself). I've recently developed a battery of gene tests to help people personalize their health. Knowing your genetic type is important here, as when it comes to CYP1A2 and coffee, there are some interesting facts.
Your genes tell you how much coffee to drink.
As I wrote in my book, The Genetics of Health people with the AA variant of the CYP1A2 gene are fast metabolizers, while those with the AC or CC subtypes of the gene are slow metabolizers. My genetic test for the CYPA12 gene revealed a normal GG variant—phew! The risky ones are the GA or AA variants. My risk was not elevated, even if (in general) it's best to limit caffeine to 300 to 400 milligrams each day. My patient has the GA variant, meaning that, if he drinks more than 200 milligrams of caffeine a day, his heart disease could end up being more than just a twitch.
Get to know your favorite beverage.
The main varieties of coffee (genus Coffea) beans are Arabica or Robusta and the latter has twice the caffeine content. How much caffeine does a cup of coffee have per cup? The results may surprise you:
- Plunger coffee: 100mg
- Filter coffee: 150mg
- Espresso coffee or cappuccino: 80mg (single shot)
- Decaffeinated coffee: Starbucks 8.6 mg, Dunkin’ Donuts 10.9 mg
- Coke: 25-35mg
- Diet Coke: 25-47 mg
- Red Bull: 80mg (like a cup of espresso)
Understanding your gene type and how much caffeine is in your favorite drink is important to make sure you're living your healthiest life—especially if you love your coffee, as your genes may have other ideas for you.