Effect of bile on vitamin B12 absorption.

The standard double-isotope Schilling test was used to study vitamin B12 absorption in seven patients with obstructive jaundice and 10 with T-tube bile duct drainage after cholecystectomy and bile duct exploration. In three and five of these patients respectively absorption was impaired. In the second group six patients were restudied after removal of the T tube, and in each case absorption was improved. Similar results were obtained after bile duct ligation in rats. Bile exclusion produced a 50-60% reduction in renal and hepatic uptake of vitamin B12 from the intestinal lumen. The malabsorption was corrected by replacing bile. These studies suggest that bile plays a part in the normal absorption of vitamin B12.     

Idiopathic hypoparathyroidism with impaired vitamin B12 absorption and neuropathy

A 68-year-old man presenting with chronic intermittent diarrhea and progressive ataxia was found to have idiopathic hypoparathyroidism. Intrinsic factor-resistant vitamin B₁₂ malabsorption was demonstrated. Both the diarrhea and vitamin malabsorption were reversed by correction of hypocalcemia.His neurological profile was a combination of peripheral nerve, posterior column and cerebellar deficits. He had calcifications in the dentate nuclei of the cerebellum. Possible etiological factors such as vitamin B₁₂ deficiency, folic acid deficiency and steatorrhea have been excluded. Posterior column and cerebellar abnormalities improved with treatment. It is postulated that hypocalcemia causes functional, reversible spinal cord and cerebellar dysfunction.     

Seasonal distribution of vitamin B12 in Lake Kinneret.

Vitamin B12 is formed in Lake Kinneret in the hypolimnion and in the sediment. The highest value of B12 recorded in the lake water was about 100 ng/liter in November and December of 1975 at a 40-m depth. The vitamin was liberated from the hypolimnion during the turnover period. This supply of the vitamin to the photic zone was accompanied by increasing biomass of Dinoflagellates, Bacillariophyta, and Chlorophyta. The decrease in the vitamin concentration, followed by an increase, is correlated with a decline and subsequent rise in the algal biomass, respectively. Cyanophyta biomass, on the other hand, increased when the vitamin concentration in the photic zone was at its lowest level.     

The vitamin B 12 serum level at various ages]

A report is presented on the determination of the vitamin B12 content by means of radioassay in the serum of 402 healthy persons aged between 14 to 98 years. With increasing age a significant decrease of the vitamin B12 content could be observed in both sexes after the sixtieth year of age. In the age group between 21 to 30 only the low values of women made an exception, which may be due to the administration of contraceptives.