Development of novel methods for separation of trans fatty acids and other nutritionally relevant or related fatty acids

Scientific research over the last two decades has demonstrated relationships between dietary intake of certain fatty acids (FA) with double bonds in the trans configuration in their alkyl chain (trans fatty acids, TFA), and the development of severe metabolic or cardiovascular diseases such as arteriosclerosis, hypertension and diabetes mellitus type-2 (Mozaffarian et. al 2006 & 2009). In response to such findings, several countries including Denmark, Canada and the United States have implemented regulations regarding limitation and labelling of TFA content of fats, oils, foods and dietary supplements. Recent studies have shown that intake of TFA with different chemical structures results in different metabolic and health effects. Dietary intake of c9,t11-18:2 and its biological precursor t11-18:1 (vaccenic acid) has been credited with positive health effects [Field et al., 2009]. In contrast, consumption of dietary t10,c12-18:2 has been associated with hyperinsulinemia and fatty liver in mouse studies [Clément et. al 2002]. However, a critical common limitation of these studies has been the availability of authentic reference materials and appropriate analytical methods to quantify the subject TFA and their metabolites. Organic synthesis of the possible FA isomers involved can play a key role in the correct identification and analysis of these TFA. Misidentification of analytes can lead to an incorrect evaluation of the health effects associated with specific FA, and therefore pure and well-characterized reference materials are essential. A classic case was reported when an overestimation of trans-16:1 isomers due to inadequate separation techniques resulted in an association of these isomers with coronary heart disease [Precht et al., 2000a]. It is interesting to note that trans-16:1n-7 has also been associated with lower insulin resistance [Mozaffarian et al., 2010]. A clear identification of the trans-16:1 isomers is definitely required in order to understand its biological significance

Impact of Dietary Resistant Starch Type 4 on Human Gut Microbiota and Immunometabolic Functions

Dietary modulation of the gut microbiota impacts human health. Here we investigated the hitherto unknown effects of resistant starch type 4 (RS4) enriched diet on gut microbiota composition and short-chain fatty acid (SCFA) concentrations in parallel with host immunometabolic functions in twenty individuals with signs of metabolic syndrome (MetS). Cholesterols, fasting glucose, glycosylated haemoglobin, and proinflammatory markers in the blood as well as waist circumference and % body fat were lower post intervention in the RS4 group compared with the control group. 16S-rRNA gene sequencing revealed a differential abundance of 71 bacterial operational taxonomic units, including the enrichment of three Bacteroides species and one each of Parabacteroides, Oscillospira, Blautia, Ruminococcus, Eubacterium, and Christensenella species in the RS4 group. Gas chromatography-mass spectrometry revealed higher faecal SCFAs, including butyrate, propionate, valerate, isovalerate, and hexanoate after RS4-intake. Bivariate analyses showed RS4-specific associations of the gut microbiota with the host metabolic functions and SCFA levels. Here we show that dietary RS4 induced changes in the gut microbiota are linked to its biological activity in individuals with signs of MetS. These findings have potential implications for dietary guidelines in metabolic health management

Products of docosahexaenoic acid (DHA) metabolism by mixed ruminal microorganisms from sheep

Trabajo presentado al 12th Euro Fed Lipid Congress (Montpellier, Francia, 14 al 17 de septiembre, 2014).The health benefits of long-chain n-3 polyunsaturated fatty acids (PUFA), specifically DHA, have been well recognized. Attempts to enrich ruminant products with DHA have not been successful due to the low transfer efficiency (<4%), the result of rumen biohydrogenation processes that are not well understood. Three sheep served as donors of rumen content that was incubated with 200 ¿g of DHA for up to 6h in anaerobic conditions (3 tubes per incubation time). Total fatty acid methyl esters (FAME) were prepared and analyzed by GC using both a 100 m SP-2560 and a 100 m SLB-IL111 column. DHA was shown to deplete to 18% of starting content, and 60% of the added DHA could be accounted for as FAME peaks eluting after 20:4n-6 compared to non-incubated tubes (0h). To further investigate DHA metabolites, the total FAME mixture was subjected to a GC-on line reduction-GC analysis. The results showed a complex mixture of C22 containing FAMEs from 22:0 to beyond 22:6. To determine the number of double bonds within the different C22 FAMEs, the mixture was analyzed by GC-time of flight-MS. Clusters of FAMEs with increasing number of double bonds from 1 to 6 were identified including FAME peaks eluting after 22:6, 22:5 and 22:4 clusters, which were tentatively identified as their conjugated fatty acids (CFA). No attempt was made to identify all members within each unsaturated C22 cluster. Based on these findings we propose that DHA is metabolized by processes of isomerization leading to CFA followed by reduction, much the same as linoleic and linolenic acids. This process appears to continue systematically until 22:0, and there is no evidence of chain shortening or elongation. The many positional/geometric isomers within each unsaturated C22 FA group suggest that the enzymes are able to attack DHA and subsequent metabolites at multiple sites. This is the first demonstrated evidence of all the DHA metabolites formed by rumen bacteria.Peer Reviewe