Drug interaction risk isn't limited to herbal supplements. Certain foods can interact with medications.
A food-drug interaction can occur when the food you eat affects the ingredients in a medication you are taking, preventing the medicine from working the way it should.
Food-drug interactions can happen with both prescription and over-the-counter medications, including antacids, vitamins, and iron pills.
Some nutrients can affect the way you metabolize certain drugs by binding with drug ingredients, thus reducing their absorption or speeding their elimination. For example, the acidity of fruit juice may decrease the effectiveness of antibiotics such as penicillin. Dairy products may blunt the infection-fighting effects of tetracycline. Antidepressants (called MAO inhibitors) are dangerous when mixed with foods or drinks that contain tyramine (i.e., beer, red wine, and some cheeses).
Not all medications are affected by food but many can be affected by what you eat and when you eat it. Sometimes, taking medications at the same time you eat may interfere with the way your stomach and intestines absorb medication. Other medications are recommended to be taken with food. Be sure to ask your physician or pharmacist for specific directions on eating prior to or after taking any medication.
People taking digoxin should avoid black licorice (which contains the ingredient glycyrhizin). Together, they can produce irregular heart rhythms and cardiac arrest; licorice and diuretics will produce dangerously low potassium levels, putting a patient at risk for numbing weakness, muscle pain and even paralysis. Licorice can also interact with blood pressure medication or any calcium channel blockers.
Aged cheese (brie, parmesan, cheddar and Roquefort), fava beans, sauerkraut, Italian green beans, some beers, red wine, pepperoni and overly ripe avocados should be avoided by people taking MAO antidepressants. The interaction can cause a potentially fatal rise in blood pressure.
And because St. Johns Wort contains the same properties as these MAO antidepressants, it stands to reason that people ingesting the herb should avoid these same foods.