As indicated by the data of Cembrowski et al, the prevalence of low serum folate levels is declining due to the addition of folate to grain products. Whether and to what extent this addition should reduce the use of serum folate determinations in the evaluation of macrocytosis and anemia is uncertain. Jacques et al1 studied a group of older adults who had plasma samples measured for folate levels before and after the fortification of grain products with folate. In this population-based study, the prevalence of low folate values was 1.7% in postfortification samples, more than 5 times as high as those values cited by Cembrowski et al. Presumably, the prevalence of low folate values in patients with hematologic abnormalities suggestive of folate deficiency would be higher still. Also, it is difficult to understand why 13% of subjects in the study of Cembrowski et al had low values for red blood cell folate because the ongoing ingestion of fortified cereal grains should normalize red blood cell folate levels.
Snow CF. Folate Is Not What It Is Cracked Up to Be. Arch Intern Med. 1999;159(22):2745. doi: