Pistachios are rich in plant sterols which may lower the absorption of dietary cholesterol from other foods. They are a good source of monounsaturated and polyunsaturated fats. These fats reduce blood cholesterol levels and lower risk of heart disease when they replace saturated fats in the diet. 
Pistachios contain phenolic compounds believed to account for the antioxidant capability for certain foods.  They are placed in the highest group for antioxidants.  
Pistachios are also an excellent source of vegetable protein.
Pistachios are also a good source of dietary fibre.
Pistachios are a good source of copper, phosphorus, magnesium and B6 and deliver 30 vitamins, minerals and phytonutrients.