Food-Drug Interactions: What You Need to Know

Older adults who take a number of prescription and over-the-counter (OTC) medications throughout the day have to be careful – not only about the way their medicines interact, but also how the foods they eat can affect their medicines.

The best way to prevent unintended – and possibly dangerous food-drug interactions – begins with information and talking to your doctor, says geriatric medicine specialist Taryn Lee, MD.

“It’s important to understand what your medical condition is and what your medications are for,” she says. “Your doctor can help you know when to take your medicine, how to space it out and why certain drugs interact the way they do with other medications or foods.”

Food and Medicine Interactions

Studies show that certain foods and drinks can delay, decrease or enhance absorption of a medication, Dr. Lee says.

Some foods that cause interactions with medicines include:

• Grapefruit, which can interfere with prescription drugs, especially certain blood pressure and cholesterol-lowering drugs.
• Processed foods, such as aged cheese, sausages and other nitrate-laden foods, which can affect how blood pressure and bacterial infection-fighting medications work.
• Black licorice, because of its effect on blood pressure medications, blood thinners and pain relievers.
• Chocolate, which affects certain antidepressant medications.
• Walnuts, which change how thyroid medications work.
• Alcohol, which can increase or decrease the effectiveness of many prescription and over-the-counter (OTC) medicines.
• Leafy green vegetables, such as broccoli, cabbage, spinach, kale and brussel sprouts,can influence how you metabolize certain drugs, for instance, blood thinners like Coumadin.

Dr. Lee talks to her patients about their diet when she prescribes Coumadin. She tells them that they don't have to avoid leafy green vegetables, but they do have to take some precautions.

“I tell them that as long as you eat the same amount all the time, you’re good,” she says. “If you have a salad two times a day or broccoli every day, that’s okay. You don’t have to say, ‘Oh, I can never have broccoli.’ It’s a matter of explaining to them how the drugs interact.”

Educate Yourself

There are a lot of do’s and don’ts with prescription and OTC medications, so it’s important to ask questions, Dr. Lee says.

“You want to educate yourself by asking your doctors questions. I encourage my patients to write down their questions. It’s helpful when I know my patient has an agenda. I have my checklist and my patient has his, which helps both of us feel happy about the visit. That makes for a successful visit.”

Taryn Lee, MD is a geriatrics medicine specialist and the geriatrics program director at University Hospitals Cleveland Medical Center.