MALNUTRITION AND IQ SCORES

See Physical Anthropology: The Core, Chapter 4, pages 85, 106-107;

Physical Anthropology, 6^th edition, Chapter 7, pages 163-165, and Chapter 8, pages 191-193.

Several studies have demonstrated a difference in IQ scores between different ethnic groups within the United States. Some attribute these differences to hereditary factors. Others, however, point out that people of different ethnic groups are often associated with differences in life style and socioeconomic level. It has often been suggested that lowered IQ scores are correlated with poverty and malnutrition. If this is true, the growing number of children in the United States that are living in poverty today means increased problems in the future as these children become adults in an increasingly complex world.

Severe malnutrition can, of course, cause very serious physical problems that often lead to death in infancy and childhood. Those that survive are often chronically ill and many suffer various degrees of brain damage. New evidence suggests that poor nutrition also directly affects the ability to think and learn, and this is reflected in lowered IQ scores.

The relationship between poor nutrition and intellectual impairment has been demonstrated in a study conducted in Guatemala. The investigation began in 1969 when the Institute of Nutrition of Central American and Panama began a study of nutritional supplements in preventing the health problems associated with poor nutrition.

Four villages were selected for the study. Both received a nutritional supplement containing vitamins and other nutrients. Two villages received a sweet drink called Fresco that contained no protein. The other two villages received Atole that contained a significant amount of protein. Between 1969 and 1977 over 2000 mothers and children received the supplements. Medical records show that both supplements improved the health of the participating villagers and decreased infant mortality. As expected, Atole, with the added protein, brought about the greatest improvement.

Years later, in 1988 and 1989, researchers revisited the former participants who were then between 11 and 27 years of age. A total of approximately 600 individuals took a battery of literacy, reading comprehension, intelligence, and other tests. It became obvious that the better performances came from those who drank the high-protein Atole in childhood. The effects were most pronounced among those living at the lowest socioeconomic levels.

Intelligence is a very complex concept; it is unlikely that one factor alone determines an IQ score. In fact the differences in IQ score between different ethnic groups tend to disappear when the individuals considered in each group are matched for income, education, health practices, and so forth. When a particular group of people show an average decline in IQ score, and when such a group occupies a low socioeconomic level associated with poor health and nutrition, it is obvious that these latter factors are the most significant factors affecting those IQ scores.

There are several conclusions one that can make from this data. First, differences in intelligence are not inherent in any particular group of people. And, second, the development of public policy directed at alleviating poverty and malnutrition will greatly aid in the effort to decrease infant mortality and illness.

References: J. L. Brown and E. Pollitt, "Malnutrition, Poverty and Intellectual Development," Scientific American (February 1996), 38-43; E. Pollitt (ed.) "The Relationship between Undernutrition and Behavioral Development in Children", Supplement to the Journal of Nutrition, 125, No. 8S (1995).