In our body, drugs share the same route of absorption and metabolism as nutrients, which create the potential for interactions.
When food affects medicine
Foods can affect drug action in many ways. The most common is when foods interfere with absorption, which can make a drug less effective. For example, calcium in milk can bind to the antibiotic tetracycline, interfering with its absorption. Nutrients or other components of food can also interfere with a drug’s metabolism, or how it is broken down in the body. Finally, foods can affect the elimination of drugs from the body.
So some drugs should not be taken with food. Other drugs must be taken with foods to prevent stomach irritation.
When medicine affects nutrients
Some drugs interfere with the absorption of nutrients. For example, some cholesterol-lowering medications reduce the absorption of fat-soluble vitamins. Others affect the body’s use or elimination of nutrients, like diuretics, which ca cause a depletion of potassium, and lead to a deficiency.
Dangerous interactions
The following are some of the more serious interactions that can occur between food and medicine:
MAO inhibitors and foods containing tyramine
Mixing monoamine oxidase (MAO) inhibitors-a class of medications used to treat depression-with foods high in tyramine produces one of the most dramatic and dangerous food-drug interactions. Symptoms include a rapid rise in blood pressure, severe headache, collapse, and even death. Foods high in tyramine include aged cheese, chicken liver, certain red wines, yeast extracts, processed meats, dried or pickled fish, legumes, soy sauce, and beer.
Grapefruit
Grapefruit juice contains a compound that can increase the absorption of certain drugs, which can result in receiving a larger dose than was intended. This effect is not seen with other citrus fruit juices. Example of drugs that are affected include AIDS medications, cholesterol-lowering “statins” calcium channel blockers, antihypertension drugs, and cyclosporine, an immune system suppressant. As a general rule it is better to stay away from taking any medication with grapefruit juice. Since compounds in grapefruit juice can stay in the blood for 24 hours, effects may be noted even if the medication is not taken directly with the juice.
Foods high in vitamin K
Vitamin K is essential for clotting blood. Foods high in vitamin K, such as Swiss chard, kale, spinach, Brussels sprouts, broccoli, and other leafy greens, can interfere with blood thinners.
Alcohol
Alcohol and medications do not mix well. Alcohol can slow down the body’s metabolism, so medication stay active longer than they should. In some cases, mixing alcohol with medication can be fatal. Try to avoid it completely when taking prescription or over the counter medication.