Protein constitutes about 20 percent of the human body and is present in every single cell. Proteins in the daily diet are essential for normal growth and development and for the maintenance of health.
- Complete proteins or High quality proteins
Proteins which contain all nine of the essential amino acids in sufficient quantities required by the body to promote growth and health are called complete or high-quality proteins. Animal foods such as milk, cheese, egg white, fish poultry and meat are complete protein sources.
- Incomplete proteins or Low quality proteins
Proteins which lack one or more essential amino acids are called incomplete proteins or quality proteins. Consequently, incomplete proteins need helping from other proteins to build tissue. Proteins found in plant foods like navy beans, pinto beans, soybeans, chickpeas are incomplete proteins.
Gelatin is the only incomplete protein found in the animal sources.