If you’re one of the nearly 70% of Americans taking prescription drugs, you may need to carefully watch what you eat. That’s because the nutrients in food can interact with drugs—often in harmful ways. Certain nutrients make certain drugs less effective than they should be…while conversely, some nutrients can make certain drugs too powerful. Also, because some drugs can deplete your nutrient stores, there are some foods that you should probably eat more of to avoid nutritional deficiencies.

If you’re taking any of the following prescription drugs, watch what you eat as described. As always, if you are on medication, check with your doctor before making any changes to your medications or supplements.

If You Take an Antibiotic

Watch out for dairy and salads. Two types of antibiotics—quinolones, which include ciprofloxacin (Cipro), ­norfloxacin (Noroxin) and ofloxacin (Ocuflox), and tetracyclines (doxycycline, minocycline and tetracycline)—may be poorly absorbed, and therefore not work as well, when combined with calcium. To prevent this interaction, wait two to four hours between taking an antibiotic and consuming a calcium supplement or calcium-rich foods such as milk, ­yogurt and other dairy products.

The absorption of antibiotics also can be decreased by large amounts of magnesium. Avoid taking a magnesium supplement or eating large amounts of magnesium-rich foods, such as leafy greens, one hour before and two hours after taking an antibiotic. Use of antibiotics also may lead to magnesium deficiency, characterized by weakness and muscle spasms. A healthy diet with plenty of fruits and vegetables, spaced two hours apart from your ­antibiotic medications, can help prevent magnesium deficiency.

If You Take an Antidepressant

Watch out for cheese, cured meat and alcohol. Certain antidepressants can be harmful when paired with foods such as chocolate, aged cheeses, cured meats and ­alcoholic drinks, which all contain tyramine, which helps regulate blood pressure. Tyramine levels are controlled by an enzyme called monoamine oxidase that is blocked by antidepressants called monoamine oxidase inhibitors (MAOIs). When high-tyramine foods are consumed by people taking MAOIs, ­tyramine can build up in the body and cause dangerously high blood ­pressure.

Many antidepressants don’t affect tyramine levels, so check with your physician or pharmacist before making significant changes to your diet.

Folate has been shown to improve patients’ response to some ­antidepressants. Talk to your doctor about whether increasing your folate intake could enhance your treatment. Folate-rich foods include leafy greens, asparagus, brussels sprouts, citrus fruits, beans, legumes and folic acid–fortified cereals.

Omega-3 fatty acids also may improve the response to antidepressant medications. Example: The combination of an antidepressant and eicosapentaenoic acid (EPA) was shown to improve symptoms of depression in some people better than an antidepressant alone. The best food sources of EPA are fatty fish such as mackerel, salmon, herring, anchovies and white tuna. Fish oil supplements also are ­excellent sources of EPA.

If You Take Estrogen

You’re at risk for vitamin depletion. Estrogen frequently is used as part of hormone replacement therapy for women after menopause. However, it can reduce the body’s folate, magnesium, vitamin B-6 and vitamin B-12 levels. A woman who follows a healthful, balanced diet is unlikely to be deficient in these nutrients even with estrogen therapy. However, someone with an unhealthy diet or limited access to fruits and vegetables and who is on estrogen therapy may benefit from supplementation with these ­nutrients.

If You Take Blood Pressure Medication

Watch out for bananas, tomatoes and leafy greens. ACE-­inhibitor drugs are commonly used to treat high blood pressure. Numerous studies have found that these drugs, which include Capoten, Vasotec, Zestril, Monopril and others, cause zinc depletion. They bind to zinc and make it unavailable for use in the body, limiting its valuable role in wound healing, new cell growth and immune function.

Someone taking an ACE inhibitor over the long term may benefit from zinc supplementation. Eating foods that contain zinc, such as oysters, beef, poultry, beans, yogurt and zinc-fortified ­cereal, also will protect against deficiency.

ACE inhibitors can interfere with the body’s potassium levels, causing a buildup of potassium over time. Get frequent blood work to make sure that your potassium levels are in check. If your potassium is high, adjust your diet as needed to minimize the intake of high-potassium foods such as bananas, tomatoes, potatoes and leafy greens.

If You Take Cholesterol Medication

Watch out for grapefruit—and check your vitamin D level. Statin drugs are widely used to reduce cholesterol levels in the blood. However, cholesterol is required for the production of vitamin D, which helps with immune function, building strong bones and the absorption of calcium.

Research is mixed on statins and ­vitamin D. Some data show that statins ­decrease the level of vitamin D in the body, while other data show just the opposite. There is some evidence that statins affect levels of the other fat-soluble vitamins A, E and K, but more research is needed to understand this relationship. If you take a statin, your best bet is to eat a variety of nutrient-rich foods, including plenty of fruits and vegetables, and talk to your doctor about any supplements you may want to take.

Better understood is the interaction between statins and grapefruit. The juice in grapefruit, in particular, amplifies the amount of certain statins in the blood, which increases the risk for statin side effects such as muscle pain and liver and kidney damage. If you’re taking simvastatin (Zocor) or atorva-statin (Lipitor), avoid grapefruit or ask your doctor about changing to a statin that is less affected by the fruit.

If You Use Birth-Control Drugs

You’re at risk for vitamin depletion. Several studies have found that birth-control drugs are associated with lower folate levels. Folate is critical for the prevention of some neural tube defects in early pregnancy, and hormone-based birth control doesn’t provide perfect protection against getting pregnant, so adequate levels of folate are important for all women of childbearing age who are sexually ­active. Heartburn medications, such as Tagamet and Pepcid, and nonsteroidal anti-inflammatory drugs (NSAIDs), such as Advil and Aleve, also can reduce levels of folate in the body.

The use of birth-control drugs has similarly been linked to depleted levels of B vitamins, vitamin C, magnesium and zinc. Choose fruits and vegetables, whole grains, fish, poultry, beans, nuts and healthy fats, along with a ­multivitamin, for optimal health.

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