Maize, also known as corn, is grown across the world and is an important food crop in many countries, especially in Latin America, Africa, Asia, and parts of the former Soviet Union. The percentage of protein in maize commonly varies between 8 and 11 percent, depending on the variety of maize. Quality Protein Maize (QPM), which is a maize variety that has been specifically developed to have a high protein content, contains approximately 18 percent protein. The main problem with the protein in maize, especially in older varieties, is that it lacks or is a poor source of two important amino acids called lysine and tryptophan that are necessary for the human body to properly metabolize protein. The poor quality of protein in maize can lead to malnutrition in the form of protein deficiency, also known as wet malnutrition or kwashiorkor, and also to a vitamin deficiency disease known as pellagra.
Nutritionally, maize is a good source of carbohydrates, vitamin B and various minerals. However, the insufficient content of lysine and tryptophan in the protein in maize makes most kinds of maize a poor dietary source of protein. It is recommended to eat maize with other types of protein, such as beans, fish, or meat. This helps provide the necessary amino acids missing from the maize, and enables the body to metabolize the protein in maize.
In some parts of the world, maize in various forms like corn meal and maize porridge is the main source of nutrition, with few other food sources. The low quality of protein in maize can lead to serious health problems in such areas. One such health problem is kwashiorkor, a form of protein deficiency in children that consume enough calories, but are still malnourished because they do not get enough protein. This type of malnutrition is sometimes called wet malnutrition. Another health problem sometimes related to maize consumption is pellagra, a vitamin deficiency that occurs when one does not get enough niacin or tryptophan.
Newer varieties of maize, such as QPM, have been developed to increase the nutritional value of maize and specifically its protein content. These varieties offer both a higher percentage of protein as well as more lysine and tryptophan, making them better dietary sources of protein. QPM is now used in maize production across the world and some studies show that its introduction has helped reduce the incidence of malnutrition and vitamin deficiency in parts of Africa and Latin America.