Intestinal Absorption and Esterification of Vitamin D3-1,2-3H in Man.

Abstract

The results of the present investigation demonstrate that vitamin D3-3H is absorbed via the lymphatic pathway in man and transported associated mainly with the chylomicrons. Similar results were decribed in work on rats. After purification of the total lipid extract on Sephadex LH 20 in combination with fractionation by thin-layer chromatography most of the administered vitamin D- H was recovered as free vitamin and very little as esters. This is in contrast to cholesterol--4-14C which is esterified to 60-80% during the absorption process in man. About 50% of the''administered radioactivity was recovered in the lymph lipids in 18hr. After administration of vitamin D33H to patient with bile obstruction and collection of the thoracic duct lymph less than 5% of the administered radioactivity was recovered. These preliminary results indicate the obligatory role of bile for the absorption of vitamin D3 in man. Similar results were obtained earlier in rats.