Separation of phospholipids and individual molecular species of phospholipids by high-performance liquid chromatography.

Unlike other macronutrients such as protein, the amounts and types of fat in the human diet vary tremendously across cultures and over time have changed significantly within Westernized countries. Studies of the effect that fat sources, fat amounts and changes in fat intake have on human disease are extremely difficult to conduct with traditional dietary assessment methods for a number of reasons. These include the hidden nature of many fats, the variation in fatty acids contained in foods and feed and the sensitivity of individuals to questions about fat intake in their diets. For these reasons biomarkers of fat intake are particularly desirable. Fat and fat-soluble substances have the advantages over other nutrients of a long half-life and readily accessible storage depots (in the absence of starvation, undernutrition or eating disorders). Technological advances in quantitative measurements of individual fatty acids, with the help of gas chromatography and mass spectrometry (GCMS)((3)) and high performance liquid chromatography (HPLC), made possible the study of specific isomers of minor fatty acids from small tissue samples. Technological advances also opened the gateways to the study of fats that represent less than 1% of the total fat profiles, such as decosahexanoic acid (DHA), eicosapentanoic acid (EPA) and conjugated linoleic acid (CLA). Biological advances enhanced our appreciation of the differences between fats of differing chain lengths within a family, including the saturated fats. Challenges remain, such as assessing total fat intake, discriminating the contribution of endogenously produced fats, determining how to evaluate the importance of relative versus absolute contributions of fat and accounting for the factors that influence deposition and mobilization of individual fats within and between individuals. Factors that can influence deposition and mobilization include genetic variation, disease status, lifestyle differences (i.e., alcohol consumption and smoking), circulating apolipoprotein levels and the hormonal milieu of the individual and the source tissue.

Biomarkers of Fat and Fatty Acid Intake

Publisher Summary This chapter discusses the metabolism of molecular species of diacylglycerophospholipids. The glycerolipid composition of cell membranes and lipoproteins is metabolically adjusted to meet specific requirements, and it does not merely reflect the supply of different fatty acids in the diet or in the cell culture medium. However, adequate adjustment cannot always be possible, and under such conditions, the cellular activity can take place in a suboptimal physicochemical environment and characteristic symptoms of a disease state can appear. As the cellular lipid composition is subject to considerable dietary and pharmacological manipulation, there can be therapeutic alterations in the composition of the molecular species of the tissues and other animal species. The metabolism of the molecular species of the glycerophospholipids is intimately involved with the activity of the acyl transferases. Therapeutic alterations in the composition of the molecular species of the glycerolipids can be feasible and can yield beneficial results in the treatment of membrane diseases.

Metabolism of molecular species of diacylglycerophospholipids.

The lipids of milk provide energy and many essential nutrients for the newborn animal. They also have distinctive physical properties that affect the processing of dairy products. In this review, the compositions and structures of both the major and minor components in milk lipids of many species are compared, and the data are discussed in terms of the nutrient requirements of the neonatal animal. The content and composition of milks from different species vary widely; presumably, these are evolutionary adaptations to differing environments. On the other hand, the distributions of lipid classes in milks are very similar. The fatty acid compositions of milks are usually complex and distinctive, depending on the nature of the fatty acids synthesized de novo in the mammary gland and those received from the diet in each species. Characteristically, they contain short- and medium- chain fatty acids not found in other tissues. Triacylglycerols, the main lipid class, of milks from different species do, however, exhibit many structural similarities.

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The Composition and Structure of Milk Lipids

High performance liquid chromatographic analysis of molecular species of phosphatidylcholine - development of quantitative assay and its application to human bile

A. Kuksis

Papers

Newer developments in determination of structure of glycerides and phosphoglycerides