VITAMIN-B-12 DEFICIENCY AND MALABSORPTION ARE HIGHLY PREVALENT IN RURAL MEXICAN COMMUNITIES

Vitamin B-12 status of rural Mexicans was evaluated in two studies, 6 y apart. In the first, a single blood sample was collected from childr en and adults, including pregnant and lactating women. Prevalence of d eficient plasma vitamin B-12 values ranged from 19% to 41% among group s, but plasma folate status was normal in all individuals. Breast milk vitamin B-12 concentration was low in 62% of samples. The second stud y was conducted in 219 children aged 18-36 mo in five communities, who se prevalence of deficient and low plasma vitamin B-12 concentrations, respectively, was 8% and 33% on entry, 3% and 22% 6 mo later, and 7% and 29% 12 mo later. Prevalence of low holotranscobalamin II concentra tions, indicating malabsorption of the vitamin, averaged 18-40% across the three same periods. Both vitamin B-12 status indicators differed significantly between communities. The widespread vitamin B-12 deficie ncy was probably caused by malabsorption, perhaps exacerbated by low d ietary intake and, for young children, maternal depletion of the vitam in.