Nutrition is the study of the interaction of nutrients and other substances in food in relation to maintenance, growth, reproduction, health and disease of an organism. The study of the human body cannot be complete without an understanding of the nutritional requirements of the body.

A nutrient is any substance that is digested, absorbed and used by the body. In other words, a nutrient is anything that nourishes a living being.

Nutrients include:

  • Carbohydrates
  • Proteins
  • Fats
  • Vitamins
  • Minerals
  • Water

Usually, foods contain multiple nutrients. For example, potatoes are rich in carbohydrates but also contain some vitamins. Similarly, bread contains proteins and vitamins in addition to carbohydrates. Foods are described as carbohydrate or protein based on the nutrient that is present in higher proportion.

Dietary fiber or roughage is the indigestible portion of food derived from plants. Even though fiber is not considered a nutrient, it is beneficial for the human body. Fiber cannot be digested and absorbed by the body but helps digestion and helps prevent constipation.

Diet is the sum of food consumed by an individual. A balanced diet is a diet that contains the proper proportions of carbohydrates, fats, proteins, vitamins, minerals, and water necessary to maintain good health.

A nutrient is considered essential if it must be obtained from an external source because it cannot be synthesized by the body. Nonessential nutrients are those nutrients that can be made by the body but they are absorbed from consumed food.

Topics in this section

  • The balanced diet
  • Carbohydrates
    • Functions of digestible carbohydrates
  • Proteins or nitrogenous foods
    • Protein quality
    • Functions of proteins
  • Fats
    • Functions of fats
  • Vitamins
    • Fat-soluble vitamins
    • Water-soluble vitamins
    • Summary of the vitamins
  • Mineral salts
  • Fiber
    • Functions of dietary fiber
  • Water
    • Functions of water
  • Disorders of nutrition
    • Malnutrition
      • Protein-energy malnutrition
    • Malabsorption
    • Obesity
    • Phenylketonuria