Monoamine oxidase inhibitors, better known as MAOIs, are a class of antidepressant medications. First introduced in the late 1950s for the treatment of depression, MAOIs remain useful for this condition and others, including anxiety and panic disorders, bulimia nervosa and Parkinson's disease. You have to follow a special diet while taking an MAOI to prevent the development of serious side effects caused by an interaction between the drug and the food chemical tyramine.
What Are MAOIs?
MAOIs block the enzyme monoamine oxidase, which breaks down several nerve-signaling chemicals called neurotransmitters. By slowing the breakdown of the neurotransmitters dopamine, epinephrine, norepinephrine and serotonin, MAOIs alter your brain chemistry, which often relieves the symptoms of depression and other psychiatric disorders. MAOIs approved for use in the United States include phenelzine, isocarboxazid, selegiline and tranylcypromine.
The Diet Connection
The enzyme monoamine oxidase is prevalent in your brain but is also present in other tissues, including your intestines and liver. In these locations, monoamine oxidase breaks down tyramine, which is found in many foods. MAOIs block the breakdown of tyramine, which can accumulate to dangerous levels unless you limit your intake of foods that contain this chemical. Excess tyramine is harmful because it enters nerve cells outside your brain and stimulates the release of neurotransmitters. Since neurotransmitter breakdown is also blocked by MAOIs, an overload quickly develops and may become life threatening.
Low-Tyramine Diet
Following a low-tyramine diet is essential while you are taking an MAOI. Tyramine is a byproduct of the amino acid tyrosine. Fermented and aged foods have exceptionally high levels of tyramine because tyrosine is broken down during these processes.
You must avoid or limit your intake of many foods while on a low-tyramine diet. A partial list of foods you should avoid while taking an MAOI includes aged cheese, such as Stilton, bleu, Camembert, and Gorgonzola; aged, smoked or dried meats, such as salami, summer sausage, mortadella and jerky; chicken and beef liver; pickled or smoked fish, such as herring and lox; sauerkraut and kim chee; yeast extract spreads; fermented bean curd and soy; and fish and soy sauce. You also have to avoid certain types of tyramine-containing alcoholic beverages, including beer, ale, red wine, vermouth, and some white wines and distilled spirits.
Your doctor will provide detailed information about what foods to avoid or limit in your diet. Always check before eating or drinking something if you are unsure whether it is safe for you.
Tyramine Reaction Symptoms
A tyramine reaction, sometimes called a "cheese reaction," may occur if you are taking an MAOI and consume too much tyramine. Most symptoms of a tyramine reaction relate to markedly high blood pressure caused by neurotransmitter overload. Symptoms to watch out for include a severe headache, confusion, nausea, vomiting, blurry vision and chest pain. With a severe tyramine reaction, you may experience seizures. Early treatment is important to prevent the possible occurrence of a stroke.
References
- "Kaplan & Sadock's Concise Textbook of Clinical Psychiatry"; Benjamin J. Sadock, M.D., Virginia A. Sadock, M.D.; 2008
- "Stahl's Essential Psychopharmacology: Neuroscientific Basis and Practical Applications"; Stephen M. Stahl, M.D., Ph.D.; 2008
- "Critical Care Toxicology: Diagnosis and Management of the Critically Poisoned Patient"; Jeffrey Brent, M.D., et al.; 2004
- Vanderbilt University Medical Center; Meal Ideas and Menus: Avoiding High-Tyramine Foods Made Easy; Kathrynne Holden, M.S., R.D.; 2006
- University of Pittsburgh Medical Center: MAOI Diet Facts
- "Drug Interactions in Psychiatry"; Domenic A. Ciraulo, M.D., et al.; 1995
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