Nutrients are substances that the body needs to live and grow. The body
requires more than 45 nutrients, and the ways they are used are as different
as the molecules, cells, and tissues they help to create. Carbohydrates,
proteins, and fats — called macronutrients — are broken down (metabolized)
to provide energy. Vitamins and minerals — called micronutrients — are not
used for energy themselves, but are needed to help macronutrients be used
for energy.