Tyramine is one of the primary substances that migraine diets attempt to eliminate. Tyramine occurs naturally in many foods and increases in potency when the protein in food ages. It is though to trigger migraine by dilating then constricting blood vessels in the brain, setting off a chain reaction that leads to a migraine episode.
It is important to avoid foods that contain tyramine, but also to eat food that is as fresh as possible to avoid the additional tyramine that develops as food sits. This is the most daunting part of the diet for me. Foods (especially high-protein foods like meat) should be cooked within a couple days of being purchased and leftovers should be frozen within 48 hours. To eliminate as much tyramine as possible, I cook or freeze ingredients within 24 hours of purchasing them and freeze leftovers within 24 hours of preparation. Frozen vegetables are an easy way to do this and they are usually picked and frozen at their nutritional peak.