By the way, doctor: Does grapefruit juice affect aspirin?

Q. I am 78, and for about 10 years, I have been taking an 81-mg aspirin every morning with a glass of grapefruit juice. I heard that it's not a good idea to drink grapefruit juice with some blood-thinning drugs. Is that true of aspirin too?

A. Like you and millions of other people, I love the taste of grapefruit juice. It also has many health-promoting substances in it. However, around 1987 it was accidentally discovered that grapefruit juice can change the blood levels of many drugs, raising several of them and lowering a few others. As you might imagine, these changes can cause side effects or reduce a drug's effectiveness. Whether a drug is affected by grapefruit juice depends on how it's metabolized in the liver.