At the end of this page are links to research that is being done. Tannins are said to be vaso-restrictors. But a migraine is caused by vaso-dilation. We would like to see a list of foods together with their tannin contents. It should include all common foods, either individually or in categories.
Tea is an important tannin beverage.
Similar questions for coffee. There is evidence that unripe strawberries, for example, have much more tannin than ripe strawberries. There is a little evidence that different people react differently to different tannins. We know one person who gets migraines from coffee and red wine, but drinks 6 cups of tea a day with no problem. Another may have started having migraines when she switched from coffee to tea.