Walnuts are low in saturated fat and high in both polyunsaturated and mono-unsaturated fat.

They are an excellent source of omega-3 and omega-6 fatty acids, particularly when bought in their shells and eaten while fresh.
Walnuts are a good source of protein, vitamin B1, B6, folate and vitamin E.
Green and unripe walnuts are rich in vitamin C. Research has found that eating regular amounts of walnuts or almonds reduces bad cholesterol (LDL) in the blood.
Calories in Walnuts: One oz/25g of walnuts contains 170 calories.
(Source: annecollins.com)