Branched-chain fatty acids (BCFAs) consist of a wide variety of fatty acids with alkyl branching of methyl group. The most common BCFAs are the types with one methyl group (mmBCFA) on the penultimate carbon (iBCFA) or the antepenultimate carbon (aiBCFA). Long-chain mmBCFAs are widely existing in animal fats, milks and are mostly derived from bacteria in the diet or animal digestive system. Recent studies show that BCFAs benefit human intestinal health and immune homeostasis, but the connection between their content, distribution in the human and their nutritional functions are not well established. In this paper, we reviewed BCFAs from various dietary sources focused on their molecular species. The BCFAs biosynthesis in bacteria, Caenorhabditis elegans, mammals and their distribution in human tissues are summarized. This paper also discusses the nutritional properties of BCFAs including influences on intestinal health, immunoregulatory effects, anti-carcinoma, and anti-obesity activities, by highlighting the most recent research progress.

Statement of Significance: Sphingomyelin from food is increasingly recognized as bioactive lipids. This review provides new insights on the dietary sources and metabolism of sphingomyelin, as well as clinical trials on gut health and infant cognitive development.Sphingomyelin (SM) is a widely occurring sphingolipid that is a major plasma membrane constituent. Milk and dairy products are rich SM sources, and human milk has high SM content. Numerous studies have evaluated the roles of SM in maintaining cell membrane structure and cellular signal transduction. There has been a growing interest in exploring the role of dietary SM, especially from human milk, in imparting health benefits. This review focuses on recent publications regarding SM content in several dietary sources and dietary SM metabolism. SM digestion and absorption are slow and incomplete and mainly occur in the middle sections of the small intestine. This review also evaluates the effect of dietary SM on gut health and cognitive development. Studies indicate that SM may promote gut health by reducing intestinal cholesterol absorption in adults. However, there has been a lack of data supporting clinical trials. An association between milk SM and neural development is evident before childhood. Hence, additional studies and well-designed randomized controlled trials that incorporate dietary SM evaluation, SM metabolism, and its long-term functions on infants and children are required.

Recently, camel milk (CM) has been considered as a health-promoting icon due to its medicinal and nutritional benefits. CM fat globule membrane has numerous health-promoting properties, such as anti-adhesion and anti-bacterial properties, which are suitable for people who are allergic to cow's milk. CM contains milk fat globules with a small size, which accounts for their rapid digestion. Moreover, it also comprises lower amounts of cholesterol and saturated fatty acids concurrent with higher levels of essential fatty acids than cow milk, with an improved lipid profile manifested by reducing cholesterol levels in the blood. In addition, it is rich in phospholipids, especially plasmalogens and sphingomyelin, suggesting that CM fat may meet the daily nutritional requirements of adults and infants. Thus, CM and its dairy products have become more attractive for consumers. In view of this, we performed a comprehensive review of CM fat's composition and nutritional properties. The overall goal is to increase knowledge related to CM fat characteristics and modify its unfavorable perception. Future studies are expected to be directed toward a better understanding of CM fat, which appears to be promising in the design and formulation of new products with significant health-promoting benefits.

Statement of Significance: Sphingomyelin from food is increasingly recognized as bioactive lipids. This review provides new insights on the dietary sources and metabolism of sphingomyelin, as well as clinical trials on gut health and infant cognitive development.Sphingomyelin (SM) is a widely occurring sphingolipid that is a major plasma membrane constituent. Milk and dairy products are rich SM sources, and human milk has high SM content. Numerous studies have evaluated the roles of SM in maintaining cell membrane structure and cellular signal transduction. There has been a growing interest in exploring the role of dietary SM, especially from human milk, in imparting health benefits. This review focuses on recent publications regarding SM content in several dietary sources and dietary SM metabolism. SM digestion and absorption are slow and incomplete and mainly occur in the middle sections of the small intestine. This review also evaluates the effect of dietary SM on gut health and cognitive development. Studies indicate that SM may promote gut health by reducing intestinal cholesterol absorption in adults. However, there has been a lack of data supporting clinical trials. An association between milk SM and neural development is evident before childhood. Hence, additional studies and well-designed randomized controlled trials that incorporate dietary SM evaluation, SM metabolism, and its long-term functions on infants and children are required.

Human milk fat (HMF) is an important source of nutrients and energy for infants. Triacylglycerols (TAGs) account for about 98% of HMF and have a unique molecular structure. HMF is highly enriched in palmitic acid (PA) at the sn-2 position of the glycerol backbone (more than 70%) and in unsaturated fatty acids at the sn-1,3 position. The specific TAG structure in HMF plays a valuable function in infant growth. Sn-2 palmitate (mainly 1,3-dioleoyl-2-palmitoyl-glycerol) is one of the structured TAGs that is commonly supplemented into infant formula in order to enable it to present a similar structure to HMF. In this review, the development of the lipase-catalyzed synthesis of sn-2 palmitate over the last 25 years are summarized, with a focus on reaction schemes in a laboratory setting. Particular attention is also paid to the commercialized sn-1,3 regioselective lipases that are used in structured TAGs synthesis, to general methods of TAG analysis, and to successfully developed sn-2 palmitate products on the market. Prospects for the lipase-catalyzed synthesis of sn-2 palmitate are discussed. (C) 2020 THE AUTHORS. Published by Elsevier LTD on behalf of Chinese Academy of Engineering and Higher Education Press Limited Company.

Conjugated linoleic and linolenic acids (CLA and CLnA) can be found in dairy, ruminant meat and oilseeds, these types of unsaturated fatty acids consist of various positional and geometrical isomers, and have demonstrated health-promoting potential for human beings. Extensive reviews have reported the physiological effects of CLA, CLnA, while little is known regarding their isomer-specific effects. However, the isomers are difficult to identify, owing to (i) the similar retention time in common chromatographic methods; and (ii) the isomers are highly sensitive to high temperature, pH changes, and oxidation. The uncertainties in molecular structure have hindered investigations on the physiological effects of CLA and CLnA. Therefore, this review presents a summary of the currently available technologies for the structural determination of CLA and CLnA, including the presence confirmation, double bond position determination, and the potential stereo-isomer determination. Special focus has been projected to the novel techniques for structure determination of CLA and CLnA. Some possible future directions are also proposed.

Conjugated linoleic and linolenic acids (CLA and CLnA) can be found in dairy, ruminant meat and oilseeds, these types of unsaturated fatty acids consist of various positional and geometrical isomers, and have demonstrated health-promoting potential for human beings. Extensive reviews have reported the physiological effects of CLA, CLnA, while little is known regarding their isomer-specific effects. However, the isomers are difficult to identify, owing to (i) the similar retention time in common chromatographic methods; and (ii) the isomers are highly sensitive to high temperature, pH changes, and oxidation. The uncertainties in molecular structure have hindered investigations on the physiological effects of CLA and CLnA. Therefore, this review presents a summary of the currently available technologies for the structural determination of CLA and CLnA, including the presence confirmation, double bond position determination, and the potential stereo-isomer determination. Special focus has been projected to the novel techniques for structure determination of CLA and CLnA. Some possible future directions are also proposed.

The first commercial infant formula, invented in 1867, contained lipids mainly from cow's milk. We now know that human milk fat differs from the milk fat of other mammals and even more from vegetable oils. Human milk fat is one of the most complex natural lipid mixtures with a unique fatty acid composition, distribution, and numerous complex lipids. Therefore, to mimic human milk fat, human milk fat substitutes (HMFSs) have been produced through the enzymatic/chemical modification of natural lipids. Researchers have become increasingly interested in use of HMFSs as functional lipids due to their nutritional effects on the growth and development of formula-fed infants. This paper discusses the history and recent advances in HMFSs. A comprehensive summary of the composition of human milk fat (fatty acids, sn-2 fatty acids, triacylglycerols, and complex lipids) and its structure (human milk fat globules), as well as the changes during the lactation period. Nutritional bases, preparation methods, and applications of HMFSs (long-chain polyunsaturated fatty acids, sn-2 palmitate, medium-chain triacylglycerols, and milk fat globule membrane supplements) have been reviewed. Legislation relating to the fat fraction of infant formulae are also presented in this paper.

The first commercial infant formula, invented in 1867, contained lipids mainly from cow's milk. We now know that human milk fat differs from the milk fat of other mammals and even more from vegetable oils. Human milk fat is one of the most complex natural lipid mixtures with a unique fatty acid composition, distribution, and numerous complex lipids. Therefore, to mimic human milk fat, human milk fat substitutes (HMFSs) have been produced through the enzymatic/chemical modification of natural lipids. Researchers have become increasingly interested in use of HMFSs as functional lipids due to their nutritional effects on the growth and development of formula-fed infants. This paper discusses the history and recent advances in HMFSs. A comprehensive summary of the composition of human milk fat (fatty acids, sn-2 fatty acids, triacylglycerols, and complex lipids) and its structure (human milk fat globules), as well as the changes during the lactation period. Nutritional bases, preparation methods, and applications of HMFSs (long-chain polyunsaturated fatty acids, sn-2 palmitate, medium-chain triacylglycerols, and milk fat globule membrane supplements) have been reviewed. Legislation relating to the fat fraction of infant formulae are also presented in this paper.