Substances in food that can be absorbed and utilized by the body are nutrients, including proteins, fats, carbohydrates, vitamins, minerals, water and dietary fiber.
Nutrients are substances that need to be taken in from the external environment in order to sustain life in a variety of normal activities. Nutrients can be categorized into two main groups based on their source, essential nutrients and non-essential nutrients. Essential nutrients cannot be synthesized in the body and must be obtained from food, while non-essential nutrients can be converted from other food components in the body and are not necessarily obtained directly from food.
Proteins, fats, carbohydrates, water and dietary fiber are present in food, consumed in larger quantities, and are metabolized in the body to produce energy and provide heat for the body. Vitamins and minerals are only required in small amounts in a balanced diet. They do not provide energy, but are essential for life-sustaining activities.
Daily supplementation of nutrients needs to be done in moderation to avoid over-supplementation causing over-nutritional problems.