Deutsche Welle: Psychology: What are anxiety disorders?.
A healthy diet with a lot of whole grains, vegetables and omega-3s can alleviate stress. What should be avoided are starchy foods like bread or pasta made from normal flour. This kind of food keeps insulin levels high. High insulin levels can lead to inflammatory reactions in the body, which can negatively affect the brain. Fresh fruit and vegetables, on the other hand, fight inflammation. There are even substances which, if eaten regularly, act like natural tranquilizers. These include omega-3 fatty acids and tryptophan. That’s an amino acid found in milk, for example.
Coffee, however, is bad for nervous people because of its caffeine. It doesn’t only wake you up, it also drives your heart rate up. The body interprets this as a stress signal.