Proteins are made up of different amino acids. The human body cannot make or cannot make enough of certain amino acids (called essential amino acids) to meet bodily needs. They must be obtained from food. Proteins are used in growth and repair of all body tissues, and for making enzymes and hormones to maintain body functions. Besides, each gram (g) of protein provides about 4 kilocalories (kcal) of energy.

Sources

Protein can be derived from two main sources, namely animal proteins (e.g. meat, poultry, fish, eggs and milk) and plant proteins (e.g. pulses, cereals, nuts, beans and dry peas). As animal proteins contain all the essential amino acids that the body needs, they are regarded as 'complete proteins'. Except for soya beans, plant proteins are 'incomplete' as they usually lack one or more essential amino acids. For example, grains are limited in lysine and legumes are limited in methionine. However, eating a combination of plant foods (such as legumes and grains, legumes and nuts or seeds) can provide enough essential amino acids.

Requirement

The World Health Organization (WHO) and the Food and Agricultural Organization (FAO) of the United Nations recommend that daily protein requirement for healthy people should be between 10-15% of daily caloric intake.

Health Alert

Lack of protein can cause growth failure, loss of muscle mass, decreased immunity, oedema, weakening of the heart and respiratory system, and even death.

Practical Tips for Going for High Quality Proteins

Foods rich in proteins (including meat, poultry, fish, eggs and dry beans) are placed at the "Eat Moderately" level of the Food Pyramid. Here are some suggestions for getting high quality proteins:

 
 

References

Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective. Washington DC: World Cancer Research Fund and American Institute for Cancer Research; 2007.

Diet, Nutrition and the Prevention of Chronic Diseases: Report of a Joint WHO/FAO Expert Consultation. WHO Technical Report Series No. 916.Geneva: World Health Organization; 2003.