Structural Effects on Absorption, Metabolism, and Health Effects of Lipids

Abstract

The structure of fatty acid-containing lipid classes is defined as the grouping or positioning of fatty acids on the alcohol backbone. Alcohol backbones considered are glycerol, phytosterols/-stanols, and sucrose. Health-related nutritional effects of food lipids depend on the fatty acids they contain (not covered here), on the alcohol backbone, on the number of fatty acids esterified on the alcohol backbone if applicable (triacylglycerols vs. diacylglycerols vs. monoacylglycerols), and on the position the fatty acids occupy. The specificity of the lipases that are present in the intestinal tract are a major determinant of the digestion products that will be formed. Different digestion products will react differently in the intestinal lumen and after absorption will be metabolized differently in the intestinal cells. Specificity of lipases in combination with different handling of different fat digestion products are at the basis of structure-related effects of food lipids. The position of fatty acids in triacylglycerols (inner or outer) can have an effect on digestibility (for saturated fatty acids), route of transport (for medium chain fatty acids), conversion in higher unsaturated fatty acids (for parent essential fatty acids), chylomicronemia, cholesterolemia, and atherogenicity. The well-known cholesterolemic and atherogenic effects of different fatty acids are more pronounced when these fatty acids are esterified at the inner position of triglycerides. Partial glycerides have nutritional effects different from triglycerides with the same fatty acid composition. 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. Keywords: fat structure; nutritional effects; glycerides; phytosterol; phytostanol