There are about 50 nutrients known to be necessary to maintain all processes in the body: protein (amino-acids), fats, carbohydrates (starch and sugars) and many vitamins and minerals.
These nutrients play an important role in many of the physiological processes necessary to maintain the body’s functions like building and repairing the body, energy metabolism and all other processes that happen in the body. The body cannot, or inadequately, produce these substances and that is why we call them essential nutrients. Nutrients are classified as macro- and micronutrients.