ABSTRACT
Dietary lipid classes usually have an alcohol and fatty acids as building blocks but other constituents can also be present. The alcohol moiety of the usual dietary fats is mainly glycerol but fats with other alcohols such as phytosterols, phytostanols, and sucrose have been synthesized and incorporated into foods with special health effects. Health-related nutritional effects of food lipids depend on their digestibility, fatty acid composition, and identity of their alcohol moiety. In the case where the alcohol moiety is a polyalcohol, the number and position of the fatty acids on the alcohol backbone is
Armand B. Christophe Department of Internal Medicine, Division of Nutrition, Ghent University Hospital, Ghent, Belgium
also important. Other lipid components such as choline, which is present in phospholipids, can also have distinct nutritional effects. The specificity of the lipases that are present in the intestinal tract is a major determinant of the digestibility of fat and of the digestion products that will be formed. Indigestible lipids will not be absorbed and may affect the extent of absorption of lipid-soluble components which are present in the dietary fat. The chemical nature of fat digestion products determines their reactivity in the intestinal lumen. This in turn affects their uptake and that of other food constituents with which they react. Likewise the lipid digestion products that are absorbed also affect intestinal transformations and metabolism. This in turn can have an influence on the physicochemical nature of the fats that leave the intestinal cells, their chyloportal repartition, and further metabolism. Specificity of lipases in combination with different handling of different fat digestion products is at the basis of structure-related effects of food lipids. The nature of the alcohol backbone of food fats is also extremely important for their health related nutritional effects. Phytosterol/-stanol esters for instance have cholesterol-lowering effects and sucrose polyesters cannot be absorbed from the intestinal tract.
