Dear Dr. Roach: I am very sensitive to caffeine. I usually have two cups of coffee in the morning but don’t consume anything with caffeine in it after about noon. If I do drink tea or soda, or eat chocolate after that time, I’ll be wide awake and my heartbeat will be racing by 2 a.m. Is there anything that I can take to counteract this effect of caffeine? — B.H.

Answer: People differ widely in their ability to metabolize caffeine. Some people have minimal effects from large amounts of coffee, but others, like you, are much more sensitive. This may have to do with different types of detoxifying enzymes (especially CYP1A2) in the liver, but this is only part of the approximately 40-fold difference in caffeine sensitivity among individuals.

In theory, substances that enhance the activity of the enzyme CYP1A2 should help metabolize caffeine faster. Cruciferous vegetables like broccoli or brussels sprouts do so, but I’m not sure how clinically relevant that effect is.

You can always switch to decaffeinated coffee/tea (or mix caffeinated and decaf to the amount of caffeine you want).