MAOI diet information on the Internet can be very confusing for someone just starting one of these antidepressant medications. Monoamine oxidase inhibitors (MAOIs) are medications that inhibit the action of the enzyme monoamine oxidase. breaks down the three chemicals in the brain which may be deficient in people with depression: norepinephrine, serotonin, and dopamine. Almost all antidepressants in use today work, …