THE ABSORPTION OF TRIGLYCERIDE FAT FROM THE INTESTINE

Abstract

From the evidence submitted in this review, it is suggested that the lipolytic hypothesis of fat absorption, in its present form, fails to explain an increasing number of observations in this field, and many of the assumptions upon which it is based are in need of reconsideration. In particular, this conception of the fat absorption mechanism maintains that fat is completely hydrolysed in the intestinal lumen, that the intestinal cell has an outer pavement membrane, that paraffins are not absorbed, that the adrenal glands control phosphorylation of fat in the intestinal cell and that no significant amt. of fatty material passes up the portal vein during absorption. None of these points is satisfactorily supported by the available evidence. In addition, the lipolytic hypothesis provides no adequate explanation of the fine emulsification of fat in the intestinal lumen, and differentiation between neutral fat and fatty acid absorp''tion, the effect of added or inhibited lipolysis, the difference between the absorption of tributyrin and long-chain triglycerides, and the improvement in fat absorption when adrenalectomized animals are adequately salt-treated. The partition theory has been put forward as an alternative working hypothesis upon which further investigation of the many outstanding problems of fat absorption might be based.