Dear Dr. Roach: I have been on Plavix 75 mg and aspirin 81 mg for years, and I drink green tea daily because of its beneficial qualities. I recently heard that green tea has vitamin K and counteracts the coagulation effect. I stopped drinking the green tea. Please discuss this in your daily medical articles. — R.H.

Answer: Although green tea leaves contain high amounts of vitamin K, brewed green tea has very little. Since vitamin K is fat-soluble, not much gets into water. A modest amount of green tea is considered safe for people taking warfarin, which works by blocking the production of vitamin-K-dependent clotting factors in the liver.

Plavix (clopidogrel) works not on clotting factors, but by preventing platelets, the blood-clotting cells, from becoming activated. Aspirin also works on platelets. So, there are two reasons you don’t need to worry about drinking your green tea.

Green tea has many properties, and there have been well-done studies that have shown health benefits from drinking it. For example, regular green-tea drinkers are at significantly lower risk of developing advanced prostate cancer. It also may reduce the risk of lung cancer.

Dear Dr. Roach: Several members of my family love poppy-seed rolls. I hesitate to make them because I’m concerned about how long it takes the body to remove the opium. If one is given a urine test after eating it, will it cause a positive result? I would hate to have a family member lose his or her job because of eating poppy-seed cake. — E.O.

Answer: Indeed, it is true that poppy seeds can cause a urine test to turn positive for opiates. Even though the poppy seeds we use for food do not have any opiate effects, the chemicals are similar enough that even a poppy-seed bagel can turn a urine test positive. For a poppy-seed roll or cake, that’s many, many more poppy seeds, and one study showed positive test results as long as 48 hours after consumption. I did find several cases of people losing their jobs for a random urine test showing positive; however, most of these people regained their jobs or had cash settlements in lawsuits.