Canned tuna is one of the regulars of Iranian kitchens. This food item is rich in protein and will not spoil for several years after purchase. They are also low in fat and calories. Canning tuna with water or oil affects its nutritional value. It is a rich source of vital vitamins and minerals such as vitamin D, selenium and iodine. Although tuna is low in fat, it is a very good source of omega-3 fatty acids.