Don't Eat This if You Take That

Beware! The foods you eat and the medications you take could be working against each other. Harmful interactions aren't limited to competing drugs you ingest; anything you put in your body can potentially alter a medication's effectiveness or cause other problems.

Madelyn Fernstrom, a nutrition and diet expert featured on NBC's Today show, and award-winning neuro-scientist and pharmacologist John Fernstrom (her husband) are the authors of a new AARP book, Don't Eat This if You're Taking That. Here's some of their advice.

Avoid cinnamon when taking diabetes medications.

Nick Ferrari

If you take blood thinners, avoid fish oil supplements

Avoid these foods if you're taking anti-depressants.

Nick Ferrari

Large amounts of fish oil also can thin the blood. Combined with these kinds of medications, this can pose a health risk. Fish contains small, dietary amounts of fish oil, so consuming fish is safe.

If taking heart medications, be cautious of dairy products.

Nick Ferrari

If you take certain statins for high cholesterol, avoid grapefruit and grapefruit juice

Grapefruit interferes with your body's metabolism of atorvastatin (Lipitor), simvastatin (Zocor) and lovastatin (Altoprev, Mevacor), so your intended dose might not be accurate. If you must drink grapefruit juice, ask your doctor to prescribe another statin that is not affected by it.

If you take medicine for diabetes, avoid too much cinnamon

This spice in large amounts can lower blood sugar — which is exactly what diabetes drugs do. That means your blood sugar could get dangerously low. A sprinkle of cinnamon in cooking is safe, but avoid taking high-dose supplements.

If you take certain anti-depressants, avoid red wine, hard cheese and chocolate

Avoid this food when taking blood-pressure medicine.

Nick Ferrari

This applies to monoamine oxidase inhibitor (MAOI) antidepressants. Red wine, hard cheese (such as Parmesan or Swiss) and chocolate contain ingredients that can be harmful to the body. (For example, they can raise blood pressure.) Normally, the body breaks them down using monoamine oxidase, but the MAOIs block this enzyme.

If you take certain heart medicines, avoid too much calcium

Statins and grapefruit juice shouldn't be paired.

Nick Ferrari

Drugs called calcium channel blockers work to lower blood pressure. Too much calcium in the diet can work against this process. Limit your daily intake from all sources — including dairy products, supplements and juices fortified with calcium — to 1,000 milligrams.

If you take a certain blood-pressure medicine … take it easy on bananas and other high-potassium foods

Angiotensin-converting enzyme (ACE) inhibitors lower blood pressure but also boost potassium retention. Eating too many foods containing potassium, such as bananas, may cause harmful effects.