Walnuts are low in saturated fat and high in both polyunsaturated and mono-unsaturated fat. Walnuts are an excellent source of omega-3 and omega-6 fatty acids, particularly when bought in their shells and eaten while fresh. The 1.5 ounces of walnuts cited by the FDA also more than fulfill the daily requirement of essential omega-3 fatty acids, a critical nutrient deficient in the American diet. Among tree nuts, walnuts are distinctive because of their concentration of omega-3 fatty acids. Walnuts contain no cholesterol and are an important source of dietary fiber and protein. They are also a good source of many vitamins and minerals including potassium, magnesium, phosphorus, copper, zinc, vitamin B1, B6, folate, and vitamin E. Research has found that eating regular amounts of walnuts reduces bad cholesterol (LDL) in the blood.