In 1929-31, Lucy Wills and her colleagues described a severe anemia among pregnant women living in conditions of purdah (seclusion) in Bombay. Because of cultural taboos, these women ate a monotonous and limited diet in which green vegetables and fruits were lacking (Wills and Mehta 1929-30; Wills and Talpade 1930-1). The anemia was characterized by a severe lowering of the red blood cell count and the appearance of large immature cells in the bone marrow and in the peripheral blood. This so-called macrocytic (large-celled) anemia was cured by giving the women a yeast extract. Subsequent studies showed that certain crude liver extracts could also cure it.
Wills also reported poor pregnancy outcomes for the Indian women who were anemic. She subsequently described the anemia in other populations who lived on diets that lacked fruit and green vegetables. Later investigations led to the isolation of a nutrient, both from liver and from green vegetables, that prevented and cured the same macrocytic anemia. This nutrient was named folic acid, or folacin. Early investigations of folic acid showed that it existed in several different forms that had a number of critical functions in cell maturation.
In other studies, researchers deliberately synthesized chemical analogues of folic acid and demonstrated that these substances not only blocked the normal activity of folic acid but also prevented cell division. Such findings led to the development of specific folic acid antagonists, including aminopterin and methotrexate, which inhibit the division of malignant cells. Methotrexate, which was the less toxic of the two substances, is now employed to control certain forms of cancer and leukemia (Roe 1990). However, it was also found that if aminopterin or methotrexate was taken during the first trimester of pregnancy, birth defects occurred in the offspring. The defects were shown in rat studies to develop if one or another of these drugs was administered during the gestational period of embryogenesis (Nelson 1963).
Another association of folic acid nutriture has been revealed more recently, namely that the risk of women bearing infants with neural tube defects, such as spina bifida, is greatly reduced if they are given supplementary folic acid from the time of conception through the first trimester. Currently, a debate continues about whether or not it would be desirable to fortify cereals with folic acid as a public health measure to prevent neural tube defects (MRC Vitamin Study Research Group 1991).
World History
