It is important to recognize food-drug interactions in management of many diseases that requires drug therapy. Medical team members should be aware that food-drug interactions can:
- Alter the intended response to the medication
- Cause drug toxicity
- Alter normal nutritional status
The terms food-drug interaction and drug-nutrient interaction are often used interchangeably. Actually, drug-nutrient interactions are some of many possible food-drug interactions. Drug-nutrient interactions involve changes to a drug caused by a nutrient, or changes to a nutrient as a result of the drug. Food-drug interactions is a broader term that describes the effects of a drug on nutritional status & may be divided into 2 broad types:
1) Pharmacodynamic interactions: affect the pharmacologic action of the drug
2) Pharmacokynetic interactions: affect the movement of the drug into, around or out of the body
Risk Factor for Food-Drug Interactions
Food-drug interactions can be caused by polypharmacy, nutritional status, genetics, underlying illness, special diets, nutritional supplements, tube feeding, herbal or phytonutrient products, alcohol intake, drugs of abuse, nonnutrients in food, excipients in drugs or food, allergies or intolerances. Patients must be individually assessed for those possible effects. Commonly, more vulnerable patients are those are in long-term treatment for chronic disease, elderly, developing fetus, infant & pregnant woman. Many drugs have not been tested on these populations, making it difficult to estimate the risk of food-drug interactions. The patient’s compliance & physician’s prescribing patterns can also affect the risk.
Effects of Food on Drug Therapy
1) Drug absorption: Food or nutrients in the stomach or intestine may act to reduce the absorption of a drug by delaying digestion, binding to minerals found in the food, or adhering to food particles. In other cases, the food may promote drug absorption.
2) Medication & enteral nutrition interactions: When liquid medications are mixed with enteral feeding formulas, incompatibilities may occur, including granulation, gel formation, separation of enteral products, resulting in clogged feeding tubes & interruption of nutrition delivery to the patients.
3) Drug distribution: Inadequate protein intake & poor nutrition can results in low serum albumin levels that lead to fewer binding sites for highly protein –bound drugs & could increase the risk of adverse effect (especially for patients with albumin levels below 3.0g/dl).
4) Drug metabolism: Food may act to enhance or inhibit the metabolism of certain drugs in the body.
5) Drug excretion: Food and nutrients may act to alter the reabsorption and excretion of drugs from the kidney.
Effects of Drugs on Food & Nutrition
1) Nutrient absorption: certain drugs may increase, decrease, or prevent nutrient absorption in the gut.
2) Nutrient metabolism: Drugs may speed up the metabolism of certain nutrients, resulting in higher dietary requirements of that particular nutrient.
3) Nutrient excretion: Drugs can increase or decrease the urinary excretion of nutrients.
Modification of Drug Action by Food & Nutrients
Food or nutrient can alter the intended pharmacologic action of medication by enhancing or opposing the medication effect. For example: the interaction between MAOI (monoamine oxidase inhibitors) & pressor agents (dopamine, histamine, tyramine, phenylethylamine) can cause enhanced drug effect. Histamine content is highest in improperly stored or spoiled fish, tuna. Below is some food & beverages containing pressor agents:
1) Food that must be avoided: aged cheese (cheddar, blue, gorgonzola, stilton), aged meats (salami, mortadella, etc), soy sauce, fermented soya bean, tofu, miso soup, fava beans, sauerkraut, kimchi, tap beer, Korean beer, concentrated yeast extract, banana peel, all casserols made with aged cheese
2) Food that may be used with caution: red or white wine (2-4 oz/day), beer (max 24 oz), alcohol free beer (max 24 oz), coffee, cola, pizza
3) Food not limited: unfermented cheese (cream, cottage, ricotta, processed), smoke white fish, salmon or anchovies, pickled herring, fresh meat poultry or fish, canned figs, raisins, fresh pineapple, beetroot, cucumber, sweetcorn, mushrooms, salad dressing, tomato sauce, peanuts, chocolate, curry powder, avocado, figs, banana, raspberries, brewer’s yeast, boiled egg, yoghurt, ice cream, English cookies, baked raised products.
Caffeine in food or beverages also increases the adverse effect of stimulant drugs & oppose the anxiety effect of tranquilizers. Ingestion of vitamin K will oppose the action of warfarin (oral anticoagulant), while other substances may enhance the anticoagulant effect & lead to serious bleeding events (Harris, 1995). Combining ethanol with certain medications will produce additive toxicity that affecting various body organs & systems.
Effects of Drug on Nutritional Status
1) Taste and Smell Alterations: Some drugs may alter one’s ability to taste and smell certain foods. Food intake may be affected due to alteration of taste sensation, reduced acuity to taste, or undesirable aftertaste.
2) Gastrointestinal (GI) Effects: Some drugs can cause irritation to the digestive tract that includes stomach upset, nausea, vomiting, diarrhea, constipation, ulcers, and gastric bleeding. Some drugs may alter gastric acidity and damage mucosal surfaces leading to decreased nutrient absorption.
3) Appetite Changes: Alterations in appetite may include suppression or stimulation of hunger leading to weight loss or weight gain.
4) Organ Toxicity: Since many drugs must pass through the liver and kidney upon excretion, hepatotoxicity (liver damage) and nephrotoxicity (kidney damage) are of primary concern.
5) Metabolic Effects: Some drugs may affect blood glucose levels by stimulating the production of glucose or inhibiting its uptake. Other drugs may inhibit insulin secretion decrease insulin sensitivity, or increase insulin clearance from the blood. This may lead to conditions known as hyperglycemia (high blood glucose), hypoglycemia (low blood glucose), or diabetes. Other medications may lead to abnormal lipid levels, causing elevated cholesterol or triglycerides.
Type of Drugs
|Cause altered taste, dysgeusia||Cardiac Drugs||Acetazolamide, Captopril, Gemfibrozil, Quinidine|
|Antineoplastics||Carboplatin, Cisplatin, Methotrexate, Interferon, etc|
|Antiinfectives||Amprenavir, Cefuroxime,Metronidazole, etc|
|CNS Drugs||Clomipramine, Levodopa, Phenytoin, etc|
|Miscellaneous||Disulfiram, Selenium, etc|
|Anticholinergic||Psychotropics||Antipsychotics (Phenothiazines , Atypical & Typical) & Antidepressants (Tricyclic & MAOIs)|
|Antihistamines||Clemastine, Hydroxine HCl, etc|
|GI Antipasmodics||Atropine, Dicyclomine, etc|
|Antiemetics, Antivertigo Agents||Dimenhydrinate, Meclizine, Scopolamine|
|Antiparkinson Agents||Benztropine, Trihexyphenidyl|
|Bladder anticholinergics||Flavoxate, Oxybutynin|
|Cause GI bleeding & ulceration||Antineoplastics||Aldesleukin interleukin-2, Methotrexate, etc|
|NSAIDs, Analgesics, Antiarthritics||Aspirin, Ibuprofen, etc|
|Immunosuppresants||Corticisteroids, Myophenolate mofetil|
|Antiinfectives||Amphotericin B, Ganciclovir sodium|
|Miscellaneous||Bromocriptine, Levodopa, etc|
|Cause diarrhea||Antibiotics||Amoxicillin, Penicillin, Tetracycline HCl, etc|
|Antiviral agents||Amprenavir, Lopinavir, etc|
|Antineoplactics||Aldesleukin interleukin-2, Methotrexate, etc|
|Oral hypoglycemic agents||Acarbose, Metformin, Miglitol|
|Gastrointestinal agents||Lactulose, Sorbitol, etc|
|Cause anorexia||Antiinfectives||Amphotericin B, Metronidazole, etc|
|Antineoplastics||Aldesleukin interleukin-2, Methotrexate, etc|
|Cardiovascular drugs||Amiodarone HCl, Quinidine, etc|
|Bronchodilators||Albuterol sulfate, Theophylline|
|Stimulants||Amphetamines, Methylpenidate HCl, Phentermine|
|Miscellaneous||Fluoxetine, Topiramate, etc|
|Increase appetite||Psychotropics||Benzodiazepine (antianxiety agents), Antipsychotics (Atypical & Typical) & Antidepressants (Tricyclic & MAOIs)|
|Hormones||Corticisteroids, Somatropin, Testosterone, etc|
|Miscellaneous||Cyproheptadine, Dronabinol, Thalidomide|
|Affect glucose levels|
|Lower or normalize glucose levels||Antidiabetics||Acarbose, Metformin, Insulin, etc|
|Cause hypoglycemia||Cardiac Drugs||Dysopyramide, Antiarrhythmic|
|Antiinfectives||Pentamidine isethionate, Antiprotozoal quinine antimalarial, Ethanol|
|Increase glucose levels||Antiretroviral agents, Protease inhibitors||Ampenavir, Ritonavir, etc|
|Diuretics, antihypertensives||Furosemide, Indapamide, etc|
|Hormones||Corticosteroid, Esterogen, Progesteron, Oral contraceptive|
|Miscellaneous||Niacin, Baclofen, Caffeine, Interferon alfa-2a antineoplastic, etc|
Excipients & Food-Drug Interactions
Excipient is an inactive ingredient added to drug formula as a buffer, binder, filler, diluent, disintegrant, glidant, flavoring, dye, preservative, suspending agent or coating. Several excipients have potential risk for interactions in persons with allergy or enzyme deficiency. Some drugs also may contain enough excipient to be nutritionally significant, such as vitamin E in Agenerase (amprenavir), magnesium in Accupril (quinapril), calcium in Fibercon, soybean oil emulsion in Propofol (Diprivan), etc.
Examples of Drug Excipients
|Albumin||Buffer||May cause allergic reaction|
|Alcohol (ethanol)||Solvent||Cause additive CNS or hepatic toxicity|
|Aspartame||Nonnutritive sweetener||Cause toxicity in PKU patients|
|Benzyl alcohol||Bacteriostatic agent||May cause allergic reactions & “gasping syndrome” in premature infants|
|Lactose||Filler||May cause lactose intolerance|
|Sugar alcohol (mannitol, sorbitol)||Filler||Can cause soft stools & diarrhea|
|Starch||Filler, binder or diluent||Intolerance in patient with celiac disease if contains gluten|
|Saccharin||Nonnutritive sweetener||No evidence of carcinogenicity|
|Sucrose||Nutritive sweetener||Significant source of calories|
|Sulfites||Antioxidants||May cause severe allergic reactions in people with asthma|
|Tartrazine||Coloring agent||May cause severe allergic reactions|
|Vegetable oil||Vehicle in some parenteral drugs||May cause allergic reactions|
Tips to Avoid Problems
There are lots of things you can do to take prescription or over-the-counter (OTC) medications in a safe and responsible manner:
- Always read drug labels carefully.
- Learn about the warnings for all the drugs you take.
- Keep medications in their original containers so that you can easily identify them.
- Ask your doctor what you need to avoid when you are prescribed a new medication. Ask about food, beverages, dietary supplements, and other drugs.
- Check with your doctor or pharmacist before taking an OTC drug if you are taking any prescription medications.
- Use one pharmacy for all of your drug needs.
- Keep all of your health care professionals informed about everything that you take.
- Keep a record of all prescription drugs, OTC drugs, and dietary supplements (including herbs) that you take. Try to keep this list with you at all times, but especially when you go on any medical appointment. The Food and Drug Administration (FDA) has a Web site where you can get more information and download a sample medicine record: www.fda.gov/cder/consumerinfo/my_medicine_record.htm7
According to Mahan & Stump (2004), the benefits of minimizing drug interactions are as follows:
- Medications achieve their intended effects
- Patients do not discontinue their drug
- The need for additional medication is minimized
- Fewer caloric or nutrient supplements are required
- Adverse side effects are avoided
- Optimal nutrition status is preserved
- Accidents & injuries are avoided
- Diseases complications are minimized
- The cost of health services is reduced
- Less professional liability
- Licensing agency requirements are met
Because of the importance of food-drug interactions in the effectiveness of medication & the overall health care provided, educational materials on each medication, including food-drug interactions, should be available in each facility for distribution to patients & approved for medical team, including pharmacists & dietitian. Documentation in the medical record is also required when instruction has been given, including assessment of the patient’s comprehension, ability & willingness to follow instruction.
Avoid Food-Drug Interactions: A Guide from the National Consumers League and U.S. Food and Drug Administration. Available at http://www.fda.gov/downloads/Drugs/ResourcesForYou/Consumers/BuyingUsingMedicineSafely/
EnsuringSafeUseofMedicine/GeneralUseofMedicine/UCM229033.pdf last accessed on May 1, 2013.
Harris, J. 1995. Interaction of dietary factors with oral anticoagulants: review & applications. J. Am Diet Assoc 95:580.
*L. Bellows, Colorado State University Extension food and nutrition specialist and assistant professor; R. Moore, graduate student. 12/96. Revised 12/08. http://www.ext.colostate.edu/pubs/foodnut/09361.html
Mahan, L.K., Escott-Stump, S., Raymond, J.L., & Krause, M.V. (2012). Krause’s Food & the Nutrition Care Process. St. Louis, MO: Elsevier/Saunders.
Mahan, K. & Stump, S.E. 2004. Krause’s Food, Nutrition & Diet Therapy. 11th Edition. USA: Elsevier.
Pronsky, Zm. Food Medication Interactions. 15th Edition. Birchrunville, Pa: 2008.
U.S. Food and Drug Administration (FDA).For Consumers: Avoiding Drug Interactions. Available at http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm096386.htm last accessed on May 1, 2013.
U.S. Food and Drug Administration (FDA). Council on Family Health. Drug interactions: What You Should Know. Available at http://www.fda.gov/downloads/Drugs/ResourcesForYou/UCM163355.pdf last accessed on May 1, 2013.