Hazelnuts contain satisfactory amounts of vitamin B6, folate, phosphorus, potassium and zinc. In addition, they are a rich source of mono- and polyunsaturated fats and contain a good amount of omega-6 and omega-9 fatty acids, such as oleic acid. The minerals and vitamins they contain contribute to promoting heart health. They are high in manganese, vitamin E, folic acid, thiamine and fatty acids that improve cognitive function of the brain and also prevent degenerative diseases. The abundant fiber, combined with potassium and magnesium, treat hypertension. They have anti-cancer effects due to the antioxidants such as vitamin E they contain. The good fats and fiber they contain help regulate metabolism and promote weight loss when consumed in moderation.