Dense sources of energy, macronutrients and micronutrients. nuts and seeds are great sources of healthful unsaturated fats (both mono and polyunsaturated). They are also usually very good sources of healthy fats, including omega 3 fatty acid. They are also solid sources of vegetable protein and dietary fiber, and are relatively low in carbohydrates (low glycemic index). Best sources for magnesium, which is an important mineral in regulating blood glucose levels for diabetics and those at risk of developing type 2 diabetes.