W. Thomas Johnson
Imagine yourself in the 1930's as the owner of a sheep station in Western Australia. It has been one of the best lambing seasons in many years and because of the large number of newborn lambs you are expecting to have a very profitable year. But something is wrong. Many of the lambs are uncoordinated to the point that they are stumbling and falling down. Some of the lambs appear swaybacked. Eventually, the sickened lambs die. You are very alarmed because your profits are disappearing and the veterinarian doesn't know how to help the lambs. Now, what promised to be a very good year is turning into a disaster.
Consider another scenario. The time is in the early 1960's and you are the parent of a newborn who seems normal and healthy except for unusually wiry, stubbly hair. However, after a couple of months your baby becomes lethargic and begins to have convulsions. In the course of trying to diagnose the problem, doctors discover that your baby's body temperature is below normal. In the weeks that follow, your baby eventually shows signs of mental retardation and continues to have seizures. Even though the doctors are greatly concerned, they can neither understand the cause nor stop the progress of the disease which later would become known as Menke's disease.
Although these events occurred in different times and places, research would show that the health problems experienced by the lambs and the baby were caused by copper deficiency. In the case of the lambs, their mothers were pastured during pregnancy on land that produced herbage with extremely low copper content. As a result, the lambs did not receive enough copper before birth to sustain normal development of the nervous system. About 35 years after the discovery that copper deficiency caused neurological problems in lambs, researchers found that infants with Menke's disease have an inherited defect that prevents the intestinal absorption of copper and deprives the brain of the copper needed for development. Thus, even though the causes of copper deficiency were different, the neurological problems of lambs under practical farming conditions and of infants with Menke's disease dramatically demonstrate that copper is essential for normal development of the brain.
It is very unlikely that dietary copper deficiency in humans would ever be severe enough to produce the profound neurological symptoms observed in copper-deficient lambs and infants with Menke's disease. However, a recent survey of dietary intakes in the United States indicated that copper consumption in all age groups, from 6-month-olds to 65-year-olds, was only 80% of the amount usually considered as adequate for a particular age. This means that women of childbearing age could be at risk for marginal copper deficiency.
Evidence from the Grand Forks Human Nutrition Research Center and other laboratories has shown that marginal copper deficiency in pregnant rats leads to changes in the brains of their offspring. These changes include structural abnormalities in the part of the brain responsible for learning and memory and poor development in the part of the brain responsible for coordination and movement. Behavioral changes also have been observed in the offspring of rats who were copper-deficient during and immediately following pregnancy. These young rats did not respond well to noises that would normally startle them. Furthermore, the abnormal response to noise persisted even when the rats were rehabilitated by feeding them diets containing adequate copper. These findings indicate that copper deficiency during pregnancy could lead to structural and chemical changes in the developing brain of the fetus or newborn that subtly but permanently affect function and behavior.
Because laboratory animals and humans may differ in their copper requirements during pregnancy, more research is needed to determine if marginal copper deficiency during pregnancy is of concern for humans. However, the findings from animals suggest that pregnant women should include regular servings of seafood, liver, beans, nuts, seeds, and whole-grained breads and cereals in their diets. These foods are good sources of copper and eating them during pregnancy may help ensure that brain development in the unborn child proceeds normally.