Food cobalamin malabsorption occurs frequently in patients with unexplained low serum cobalamin levels.

Malabsorption of food-bound or protein-bound cobalamin with normal absorption of free cobalamin has been described in studies of patients with gastric dysfunction. We used the egg-yolk cobalamin absorption test to study 47 patients selected not because of known gastric disorders but because they had low serum cobalamin levels with normal Schilling test results. Their egg test results were significantly lower than in normal controls, while Schilling test results were normal. Twenty of the subjects had egg test excretion below 1.5%. No features distinguished them from the 27 who excreted more than 1.5% other than the presence of lower pepsinogen I:II ratios. Eight of 19 tested patients with food cobalamin malabsorption had no evidence of abnormal gastric status by blood tests and/or gastric analysis. Also noteworthy was the finding of food cobalamin malabsorption in 60% of tested patients who had neurologic, cerebral, or psychiatric abnormalities. Food cobalamin malabsorption appears to be associated frequently with otherwise unexplained low cobalamin levels. Low cobalamin levels in patients with normal Schilling test results cannot be dismissed as insignificant without also testing for food cobalamin malabsorption, whether or not the patients have known gastric dysfunction.