Nutrients are substances obtained from food and used in our bodies to promote growth, maintenance and repair. There are 6 classes of nutrients that our body needs to function, they are carbohydrates, protein, fat, water, vitamins and minerals. In each of these 6 classes there are then subclasses, essential and nonessential. Nonessential nutrients are those that our bodies need to function but we produce enough to meet our needs and therefore do not need to be obtained from food sources. Essential nutrients are those that our body requires and cannot produce enough of therefore are obtained through dietary intake.