Polyunsaturated fats can set up chronic inflammatory responses in brain tissue and foster blood damage. They are also harmful to blood vessels and ultimately blood circulation. These oils are usually included in processed foods such as salad dressings, fries, doughnuts and most margarines. Even worse are hydrogenated vegetable oils. These oils are used in process foods such as micro-wave popcorn, boxed cakes, TV dinners, etc.
Sugar is another food to avoid.
Eating too much sugar can lead to insulin resistance which upsets the glucose level in the blood. This may lead to permanent damage to brain cells. Simple carbohydrates turn instantly to sugar within the body. Some scientist feel that eating white potatoes or white bread is just like eating candy. Carbohydrates influence mood.