Vitamin B12 Transporters

Human intrinsic factor expressed in the plant Arabidopsis thaliana

“…Vitamin B 12 (cobalamin, Cbl) is the most complex of the vitamins [1]; it is a complicated system with three transporting proteins and several receptors which together ensure its efficient uptake [2–4]. Intrinsic factor (IF) is responsible for intestinal absorption of vitamin B 12 facilitating its internalization [2,3,5]. Lack or malfunction of this Cbl binder hampers the uptake of the minute amounts of the vitamin present in food.…”

Vitamin B12 deficiency in hypersecretors during long‐term acid suppression with proton pump inhibitors

“…B12 absorption begins with peptic cleavage in the stomach, at acid pH of food‐bound B12, which then binds to salivary R protein 26, 33, 34 . Next, in the duodenum, pancreatic enzymes release R‐protein‐bound B12, which then binds to IF.…”

“…Absorption of dietary B12 is a multistep process 26 which may be subject to disruption at one or more key steps and, where found with PPI treatment, has been ascribed to impaired release of food‐bound B12 9 because of excessive acid suppression. However, gastric acid output, when measured in other studies, 3–7 was reported in the basal state [basal acid output (BAO)] only, without stimulation, leaving uncertain the true rates of achlorhydria and the explanation of this mechanism of the PPI effect on B12 absorption.…”

Nanotechnology on Duty in Medical Applications

“…In particular, molecules such as luteinizing hormone releasing hormone (LHRH) analogues, alpha-interferon, erythropoietin, and granulocyte colony stimulating factor (G-CSF) have been studied. These pharmaceuticals have been linked covalently to the vitamin B12 molecule [171,172]. This system relies upon the natural uptake mechanism for vitamin B12 to cotransport peptides and proteins linked to the vitamin B12 from the intestine into the circulation.…”