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Art and Life
Home News Tribune Online Tuesday, March 18, 2008
By Kalyani Patel -
Correspondent
Some foods,medications aren't perfect together
You won't find grapefruit juice on the menu we give our patients. That's because grapefruit juice can increase blood concentration of cholesterol-lowering drugs called statins — such as Lipitor, Zocor and Mevacor — leading to side effects such as muscle pain and weakness.
Grapefruit juice also can interfere with calcium channel blockers, estrogen-containing oral contraceptives and certain immunosuppressant drugs used after organ transplant. It can reduce the effectiveness of Viagra, Levitra and Cialis, which treat erectile dysfunction. Certain antidepressants, such as Anafranil, also are affected by grapefruit juice.
It's not enough to ask if medicine should be taken on a full or empty stomach. You also have to ask what over-the-counter drugs, prescription medications or nutritional supplements might interact.
And you also have to ask whether foods or beverages can interact with the drugs you take. If you're in a hospital, this is done for you through the hospital's pharmacy and dietary departments. But it can get tricky when navigating on your own, especially now that so many foods are fortified with vitamins and minerals.
Some food inhibits the effectiveness of some medicines. Some foods and medicines just don't mix. Some medications shouldn't be taken with certain types of beverages or foods. For example, the acidity of fruit juice might decrease the effectiveness of antibiotics such as penicillin.
Dairy products can blunt the effects of tetracycline. Certain antidepressants — called monoamine oxidase, or MAO, inhibitors — are dangerous when mixed with foods or drinks that contain tyramine, such as beer — even nonalcoholic beer — red wine and aged cheeses. High-protein foods that have been aged, fermented, pickled or smoked are unsafe for patients taking MAO inhibitors.
That's why when you receive a prescription you need to check with your doctor or pharmacist. You not only have to read the label, but the information the pharmacist prints out for you. You also can consult with a clinical dietitian if you need help sorting out food and medicine questions.
Not all medicines are affected by food, but here are some of the more common drug and food interactions:
- Coumadin and Vitamin K: The blood thinner Coumadin, or warfarin, prevents harmful blood clots by
blocking the action of vitamin K in the liver, which decreases the production of clotting factors. If you increase your vitamin K consumption, you reduce the effectiveness of Coumadin.
Foods rich in vitamin K include green leafy vegetables such as kale, boiled fresh spinach, cooked turnip greens, boiled collard greens, raw Swiss chard, boiled mustard greens, raw red or green cabbage, raw parsley or cooked coriander leaves. Also high in vitamin K are pistachios, dill pickles, okra, canned peas, dried plums, soybeans, black and green teas, among other foods.
That's not to say you have to entirely avoid these foods. Here, portion size becomes all-important. We tell our patients taking Coumadin they can have green leafy vegetables like cooked kale, but they should have one serving per day and that serving should be limited to a half cup. An alternative might be greens that are moderately high in vitamin K, such as raw spinach, raw broccoli, raw endive and Romaine lettuce.
We also caution our Coumadin patients about cranberry juice and cranberries. Cranberries can actually increase the anticoagulant effects of Coumadin, so cranberry juice, cranberries or other cranberry products should be avoided.
- Calcium and Antibiotics: Dairy products containing calcium can bind with certain antibiotics, decreasing their absorption and rendering them less effective. While most pharmacists will warn against taking antacids and dairy products when taking tetracyclines and some fluoroquinolones, consumers have to be mindful that some foods are fortified with calcium, such as orange juice.
Take dairy products, calcium supplements or calcium-fortified foods several hours after taking antibiotics. The same is true with antifungal drugs, such as Diflucan, Grifulvin, Nizoral and Sporanox.
- Vitamin C and Fruit Juices: More fruit juices are fortified with vitamin C and other vitamins. The absorption of amphetamine-containing drugs, such as Adderall, which is used to treat attention deficit disorder, is altered when taken with acidic food, juices or vitamin C. Amphetamines are absorbed in alkaline environments, so acidic fruits or juices impairs that absorption and lessens the effectiveness of the drug.
- Fiber: Fiber binds certain drugs, resulting in decreased concentrations and less effectiveness. A person with diabetes who tries to decrease her cholesterol by eating oatmeal after taking the diabetes drug metformin, might be worsening her diabetes control by rendering the drug less effective.
The hypothyroid drug Levothyroxine also is altered when taken with fiber. The drug digoxin, which is used to treat conditions such as congestive heart failure and atrial fibrillation/atrial flutter, also can be affected by a high fiber intake.
And many drugs are affected by alcohol. Drug interactions with alcohol are numerous, too numerous for this article. Just a few examples are antidepressants, barbiturates, antihistamines, opiates, muscle relaxants, antipsychotics and anticonvulsants. When these drugs are taken with alcohol, patients are at an increased risk of motor impairment, respiratory depression, falls and accidents.
Use of alcohol and nonsteroidal anti-inflammatory drugs — such as aspirin, acetaminophen and naproxen — can cause liver damage and stomach bleeding. You have to be extremely careful with alcohol when you are taking medication.
So when you get a prescription, ask questions. Ask about when to take the drugs, on a full or empty stomach. Also ask if there are foods you should avoid taking with your medicine, foods you need to consume less of or eat or drink at different times. Read the materials you're given.
Also, be consistent with where you fill your prescriptions. When you get medications from different places, the profile is not complete, so drug-drug or drug-food interactions are easily missed.
Kalyani Patel, MSRD, is a master's prepared clinical dietitian with Robert Wood Johnson University Hospital in Rahway
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