In 2012, Dr. Franz H. Messerli conducted a somewhat tongue-in-cheek study on chocolate consumption and cognitive function. His research concluded that countries with the highest rates of chocolate consumption (i.e. Switzerland, Sweden and Denmark) also had the highest number of Nobel Prize winners.
Many of the world's greatest minds also happened to be vegetarians. Among them was Albert Einstein, who adopted the meat-free lifestyle near the end of his life. Although he was a late adopter, it appears that he supported the idea of vegetarianism throughout his life, writing to Max Kariel in 1953: "I have always eaten animal flesh with a somewhat guilty conscience."
If you're looking to include more brain-boosting foods in your diet, nutritionists today recommend a healthy dose of omega-6 and omega-3 fatty acids. These are found in nuts and fish. Antioxidants are also very important to brain development, and are found in berries, nuts and many vegetables. Even dark chocolate often makes the list of foods that can be good for you in moderation (maybe those geniuses were onto something, after all).
So what's the takeaway? The eating habits of the world's greatest minds are as varied as the individuals themselves, and it can be difficult to boil that all down into one surefire Genius Diet. Ultimately, you should eat things that are good for you, as well as things you enjoy eating. The author Michael Pollan sums it up nicely, saying: "Eat food. Not too much. Mostly plants."