Effect of folate deficiency on vitamin B12 absorption

In three different groups of patients presenting severe folate deficiency (purely nutritional folate deficiency, chronic alcoholism or various intestinal diseases), vitamin B12 absorption has been tested by Schilling test in order to investigate the possible effect of folate deficiency on B12 absorption. Following this study, it appears that folate deficiency in itself, even severe, cannot induce vitamin B12 malabsorption, since in the first group, consisting of malnourished old people, the Schilling test was always normal even in those who presented a lowered B12 serum level; in the group of patients with intestinal disease, the Schilling test was abnormal as expected in some patients; 3 alcoholics out of 12 presented a malabsorption of B12 on the Schilling test; the follow-up of 2 of them exhibited complete correction after normal diet and alcohol suppression. Consequently, folate deficiency does not seem responsible for a secondary B12 malabsorption unless another etiological factor is present, such as alcohol or ileopathy.