Folate Balance in Dietary-Induced Megaloblastic Anemia

In alcoholic subjects megaloblastic hemopoiesis rapidly develops during dietary deprivation and ethanol ingestion. To study the interaction of poor diet, depleted body folate stores and ethanol, two subjects in whom megaloblastic hemopoiesis previously developed within three weeks on a deficient diet combined with ethanol were restudied on a low-folate diet alone. The sequence of hematologic changes differed from that previously described. The curve for serum folate depletion was biphasic; the first phase reflected decreased dietary folate, and the second phase reflected folate store depletion. Not until the serum folate reached a plateau did bone-marrow changes occur. Peripheral blood abnormalities did not appear until after the marrow was megaloblastic for one to two weeks. In this study, megaloblastic hemopoiesis appeared in five to 10 weeks, as compared to 19 weeks in Herbert's classic study. Although ethanol seems to accelerate megaloblastic change, this study confirms the critical role of folate stores in determining the onset of tissue folate deficiency on an inadequate diet.