On “Today’s Health,” we take a look at how food and drugs mix — or don’t mix. If you’re taking antibiotics, cholesterol-lowering medications or basic pain relievers, such as aspirin or ibuprofen, there certain foods you should avoid. Madelyn Fernstrom, a “Today” contributor, and director of the Weight Management Center at the University of Pittsburgh, was invited on the show to tell you what foods you should avoid, if you’re taking medication. Here’s her advice:
Basically, there are three ways foods interact with medicines:
- Interfering with how the medicine is digested and absorbed by the body. For example, milk blocks iron absorption in the stomach. Calcium found in dairy products can bind some medications, such as iron supplements and some antibiotics (Cipro and Levaquin, a quinolone.)
Other foods, containing higher levels of fat and fiber, slow down the rate at which your stomach empties and the rate at which your medication is absorbed by your body. So your dose is smaller than expected. - Blocking how the medicine is broken down, or metabolized, in the either the intestines or liver. The body breaks down drugs and eliminates them in urine, which is why we take medications daily or several times a day. Grapefruit juice blocks enzymes in the intestines that break down certain drugs, such as cholesterol-lowering ones, heart medicines, and immunological drugs. (Grapefruit juice has also been shown to reduce activity of allergy medicines, like Allegra, so its effects are not consistent.) Since the body metabolizes less medicine, more circulates in the bloodstream, as much as two to three times as much, which greatly increases the likelihood of side effects.
- Mimicking the drug’s action. Some foods, or drinks, exaggerate the drug’s effect, so it’s as if you were taking a higher dose. And there’s a much greater likelihood of side effects. Alcohol, for instance, acts on the same brain circuits as sedatives. Caffeine boosts the effects asthma medications, which contain theophylline.
Here are some foods and beverages to avoid:
- Grapefruit juice: It affects some cholesterol-lowering agents, some heart medicines, some immune system drugs, and some allergy medicines, such as Allegra. Grapefruit juice blocks the action of enzymes in the intestines that metabolize many drugs. Not all citrus fruits contain this enzyme. Grapefruits, however, contain an active component (as of yet, it's not precisely known) that produces this effect. Grapefruit juice should be avoided during treatment with a number of heart medicines, including calcium channel blockers, such as felodipine (Plendil), nisoldipine (Sular), and nifedipine (Procardia.) Drugs acting on the immune system, like cyclosporine (Sandimmune and Neoral), are also affected by grapefruit juice. Many of the popular cholesterol-lowering agents (statins) have huge increases in activity when consumed with grapefruit juice. These include simvastatin (Zocor), lovastatin (Mevacor), and atorvastatin (Lipitor).
- Vitamin K-rich foods: Deep green vegetables, such as broccoli, spinach, asparagus, and red leaf lettuce, enhance the properties of blood thinners, such as Coumadin. Blood thinners prevent clots from forming, so foods rich in vitamin K, which promote blood clotting, counteract the medicine’s effect.
- Dairy products: They affect iron supplements and some antibiotics. Calcium found in dairy products interferes with absorption of iron supplements and antibiotics like Cipro and quinolone (Levaquin), so you get less of the active compound circulating in your bloodstream.
- High fiber foods: They affect some antibiotics, such as penicillin. Since fiber slows the rate that the stomach empties, the rate of medication absorption is slowed as well, giving you a lower blood dose than expected.
- Red wine and hard cheese: They contain a compound called “tyramine” that acts the same way on brain neurons as the antidepressant class called monoamine inhibitors (Parnate.) So they increase the drug’s effect.
- Alcohol: It affects antidepressants, antihistamines, sleeping pills, sedatives, and some antibiotics.
- Coffee and caffeinated drinks: Caffeine affects asthma medicines, anti-anxiety drugs.
What should you look for on labels? What should you ask your doctor? Or pharmacist?
- Make sure to read the label. Look for foods to avoid.
- Ask your doctor if you need to avoid any foods when taking your prescription. Make sure to ask if you just need to avoid the foods only when you take your dose, or if you have to avoid them while you’re on the drug.
- Check with your pharmacist when picking up your prescription, if there are any interactions with foods or beverages.
- If you do not start feeling better, or feel worse, after starting your medicine, call your doctor. It might be related to particular foods or the way you are taking the medicine.
Dr. Fernstrom’s Bottom Line:As a general rule, drink a lot of water when you take medicines help with digestion and absorption, and to minimize upsetting your stomach.
Madelyn Fernstrom, Ph.D., CNS, is the founder and director of the University of Pittsburgh Medical Center’s Weight Management Center. An associate professor of psychiatry, epidemiology, and surgery at the University of Pittsburgh School of Medicine, Fernstrom is also a board-certified nutrition specialist from the American College of Nutrition.
PLEASE NOTE: The information in this column should not be construed as providing specific medical advice, but rather to offer readers information to better understand their lives and health. It is not intended to provide an alternative to professional treatment or to replace the services of a physician.