Dark Green Vegetables and Migraines?

World-wide, approximately 1 billion people suffer from migraines. These debilitating and recurrent headaches, blight people's lives. It is obvious, however, that 'curing' such conditions can never be based on single cases. One-off observations can, however, be used as a starting point for proper investigation. A 60 year-old US photographer, had suffered severe migraines for more than 10 years. He seems to have been cured, by a dietary change (https://www.theguardian.com/science/2021/nov/18/mans-severe-migraines-completely-eliminated-on-plant-based-diet). The man, in question, had tried medication, yoga and meditation, all without benefit. The patient then cut down his intake of meat and carbohydrates, switching to consuming 140g of raw or cooked dark green vegetables (like broccoli) each day. His food was washed down with almost a litre of green, vegetable smoothie. The photographer's migraines disappeared and he has now been without headaches for 7 years. This 'observation' would have to be validated in a proper trial, before the dietary change could be widely recommended as a potential cure. There is, of course, no guarantee that all migraines have the same causal factors.