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. Like many of us, I fancy myself an amateur barista. So how much should we be having?
The most widely used drug in the worldWhen it comes down to it, the main active ingredient in coffee is caffeine. Caffeine is a plant alkaloid that occurs naturally in coffee, tea, guarana and kola 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 ailments like migraines. Many carbonated drinks also contain caffeine and when present, manufacturers automatically increase sugar content, as caffeine dulls sugar taste receptors. This increased sugar is what makes soda especially bad for you.
We metabolize 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). 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 drinkThose of us 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. 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. However, my patient had 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 beverageThe main varieties of coffee bean are Arabica or Robusta and the latter has twice the caffeine content. So how much caffeine does a cup of coffee have per cup? The results may surprise you:
- French press coffee: 100 milligrams
- Filter coffee: 150 milligrams
- Espresso coffee or cappuccino: 80 milligrams (single shot)
- Decaffeinated coffee: 8.6 milligrams
- Coke: 25-35 milligrams
- Diet Coke: 25-47 milligrams
- Red Bull: 80 milligrams (like a cup of espresso)