I've suffered from migraines since I was 17, and I'm now 45. Several years ago I went to a nutritionist for advice and she suggested I remove aspartame, (also known as Nutrasweet or acesulfame potassium) and caffiene from my diet. It has worked miracles for me. Since then I've gone from 2 migraines/week to 1 every 3-6 months!
*A note of caution, one week after quitting my daily diet coke, I awoke from a deep sleep in the middle of the night with a migraine (first and only time that's ever happened to me). As the nutritionist explained it to me, my strong reaction to withdrawal from caffeine and nutrasweet actually indicated how necessary and important it was for me to quit them both.