Nutrients are the external chemicals that the cell needs to perform its vital functions. They can be:
Macronutrients in a diet
Macronutrients or immediate principles (required in large quantities).
Proteins are primary macronutrients for the growth and maintenance of body structure (including muscle). They cannot be stored so they must be replenished daily through the diet.
Value or biological quality of proteins is the ability of a certain protein to provide all the amino acids necessary for humans. It is greater the more similar its composition is to that of human proteins, in fact the pattern with which they are compared is the protein of breast milk.
Fats are the long-term energy source and energy reserve (adipose tissue) of the body, necessary for absorption and transport of fat-soluble vitamins and constitution of hormones and cell membranes.
Carbohydrates are the body’s primary energy source, burned as glucose and stored in muscle as glycogen (excess as fat).
Dietary micronutrients
Micronutrients (required in small quantities)
Vitamins, organic molecules essential for biochemical transformations necessary for metabolism.
Minerals or inorganic substrates of life.