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Be Aware of Food-Drug Interactions

By Tammy Roberts, MS, RD, LD,
Nutrition and Health Education Specialist
Barton County University of Missouri Extension


We eat food to help our bodies function normally. We take medicine to cure an illness or to be able to enjoy optimal health. It’s hard to imagine but food can actually affect the ingredients in some medicines preventing them from working the way they should.

Calcium-rich foods

Calcium in milk and milk products can decrease the absorption of some antibiotics.


Some ways that food and drugs interact include:

  • Food can speed up or slow down the action of the drug
  • Some drugs can delay or prevent the absorption of nutrients
  • Drugs may make you want to eat more food or suppress your appetite
  • Some foods are known to alter the chemical action of a drug so that it loses its intended effect on the body

Some examples of food-drug interactions include:

  • Calcium in milk and milk products can decrease the absorption of some antibiotics. The usual recommendation is that the food and medicine are consumed at different times.
  • Foods that are acidic such as citrus juice can actually help with absorption for someone taking an iron supplement.
  • High doses of antacids can lead to phosphate depletion. In severe cases, this could lead to vitamin D deficiency.
  • Foods high in vitamin K such as cabbage, spinach, beef liver and oils can counteract the blood thinning effects of anticoagulants

The above interactions do not occur every time a person takes a drug. They are mentioned only to make you aware. Some people are more likely than others to have a reaction. Those people that have been taking certain drugs for long periods of time, take two or more at the same time, or who are poorly nourished to begin with are more at risk.

There’s no need for alarm. There are ways to help assure you get the greatest benefit from a drug.

  • Always let your physician know about every other drug, even over-the-counter drugs, or herbal supplement you are taking.
  • Make sure you understand how and when the drug should be taken. Ask if there are any foods that should be avoided.
  • Consult with your physician before consuming alcohol if you are on medication.
  • If you have been taking a drug for a long time, ask your physician if there is a risk of a vitamin or mineral deficiency.




Last update: Tuesday, May 05, 2009








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