Minerals and Vitamins

The nutritional disease pellagra, which is caused by a deficiency in niacin, is associated with maize-based diets in the Americas and Africa. While niacin is readily available in corn, it exists in a bound form (niacytin) that is not biologically available to monogastric (single-stomach) animals. Furthermore,

In the early twentieth century, hundreds of thousands of people in the southern United States suffered from pellagra, a serious disease that affects people whose diet does not include enough niacin. Pellagra occurs in cultures that depend on corn as a dietary staple, because the niacin in corn is difficult to digest and is often removed during processing. [Photograph by Ed Bohon. Corbis. Reproduced by permission.]

most of the niacin in the kernel (63%) occurs in the outermost layer of the endosperm. This layer is often removed with the pericarp during dehulling. In Mexico, Guatemala, and other countries, maize is treated with an alkaline solution of lime, which releases the niacin and helps prevent pellagra. Furthermore, pellagra seldom occurs among people in Latin America, since they eat tortillas—tortilla preparation greatly increases the bioavailability of the niacin in maize.

Persons suffering from pellagra usually appear to be poorly nourished, and they are often weak and underweight. They also exhibit dermatitis, diarrhea, and dementia. If untreated, pellagra can result in death. Niacin supplements bioavailability: availability to living organisms, based on chemical form dementia: loss of cognitive abilities, including memory and decision-making diet: the total daily food intake, or the types of foods eaten polyunsaturated: having multiple double bonds within the chemical structure, thus increasing the body's ability to metabolize it fatty acids: molecules rich in carbon and hydrogen; a component of fats antioxidant: substance that prevents oxidation, a damaging reaction with oxygen calcium: mineral essential for bones and teeth nutrition: the maintenance of health through proper eating, or the study of same lipid: fats, waxes and steroids; important components of cell membranes fiber: indigestible plant material which aids digestion by providing bulk are available to aid in the treatment of the disease. There are also several methods of increasing niacin content in maize-based diets, including:

• Complementing maize-based diets with nuts and fish, which are rich in niacin.

• Preparing maize in a way that retains the outer layer of the endosperm, contributing more niacin to the diet.

• Cooking maize in alkaline solution to increase niacin availability, a procedure commonly used in Latin America in the preparation of tortillas.

Maize is a good source of vitamin B and B12. Yellow maize can provide substantial amounts of vitamin A, and the maize germ is rich in vitamin E. Furthermore, maize oil contains a high level of polyunsaturated fatty acids and natural antioxidants (Okoruwa, 1996). However, of the three major cereal grains (wheat, maize, and rice), maize has the lowest concentration of protein, calcium, and niacin.

Dietary preferences, processing, and mode of preparation affect the contributions of maize in human nutrition. For example, the nutritive value of the grain may increase or decrease depending upon the method in which it is processed (the milling of maize reduces the concentration of protein, lipids, and fiber). Diets that rely heavily on corn may require the consumption of complementary foods to supplement its deficiency in certain amino acids and vitamins. see also Native Americans, Diet of; Rice-based Diets.

Ranjita Misra

Bibliography

Latham, Michael C. (1997). Human Nutrition in the Developing World. Rome: FAO Publishing.

Internet Resources

Eastern and Central Africa Maize and Wheat Research Network. "About ECAMAW." Available from <http://www.asareca.org/ecamaw>

Okoruwa, Augustine (1996). "Nutrition and Quality of Maize." International Institute of Tropical Agriculture. Available from <http://www.iita.org/info>

Food and Agriculture Organization of the United Nations. Maize in Human Nutrition. Available from <http://www.fao.org/docrep>

psychological: related to thoughts, feelings, and personal experiences stress: heightened state of nervousness or unease

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