Trans-11–18: 1 is effectively δ9-desaturated compared withTrans-12–18: 1 in humans

Abstract

The aim of this human intervention study was to evaluate the D9-desaturation of trans-11-18 : 1 (trans-vaccenic acid; tVA) to cis-9,trans-11-18 : 2 (c9,t11 conjugated linoleic acid; CLA) and of trans-12-18 : 1 (t12) to cis-9,trans-12-18 : 2 after a short-term (7 d) and a long-term (42 d) supplementation period. The conversion rates of both trans-18 : 1 isomers were estimated by lipid analysis of serum and red blood cell membranes (RBCM). Subjects started with a 2-week adaptation period without supplements. During the 42 d intervention period, the diet of the test group was supplemented with 3 g/d of tVA and 3 g/d of t12. The diet of the control group was supplemented with a control oil. Serum tVA and t12 levels in the test group increased by fivefold and ninefold after 7 d, respectively, and by eight-and 12-fold after 42 d, respectively, when compared with the adaptation period (P#0·002). The serum c9,t11 CLA levels increased by 1·7-and 2·0-fold after 7 d and 42 d, respectively (P#0·001). After 42 d, the test group's RBCM c9,t11 CLA content was elevated by 20 % (P¼ 0·021), whereas in the control group it was decreased by 50 % (P¼ 0·002). The conversion rate of tVA was estimated at 24 % by serum and 19 % by RBCM. No increase in c9,t12-18 : 2 was observed in the serum and RBCM, and thus no conversion of t12 could be determined. In conclusion, the endogenous conversion of dietary tVA to c9,t11 CLA contributes approximately one quarter to the human CLA pool and should be considered when determining the CLA supply.

Effect of linseed supplementation of the gestation and lactation diets of dairy ewes on the growth performance and the intramuscular fatty acid composition of their lambs

“…In the present study, the CLA level reached 20 mg/100 g of meat, which is in line with those reported in other studies on suckling lambs (Serra et al, 2009). Assuming a 20% to 25% conversion rate in the human body of vaccenic acid to CLA, the measured vaccenic acid level would provide 5 mg of CLA (Kuhnt et al, 2006). By adding the CLA and the vaccenic acid converted into CLA, lamb meat produced using this feeding strategy would provide approximately 25 mg of CLA/100 g of meat.…”

In vitro fermentation of nuts results in the formation of butyrate and c9,t11 conjugated linoleic acid as chemopreventive metabolites

“…The fatty acid (FA) composition of in vitro fermented nut samples (FP) was analyzed via GC (GC-17A V3 equipped with an autosampler AOC-5000 and a flame ionization detector; Shimadzu) as described by Kuhnt et al [18]. Therefore, lipids were extracted from 0.5 g FP as described by Folch et al [26] using a mixture of chloroform/methanol/NaCl (v/v/v 2:1:1) and transesterified with 0.5 N methanolic sodium hydroxide (100 °C, 10 min) and 1 mL methanolic BF3 solution (10 %, w:w; 100 °C, 5 min).…”

“…In contrast, natural occurring tFA such as C18:1t11 (tVA, trans vaccenic acid) and conjugated linoleic acids (CLA) might be associated with positive health effects as reviewed by Gebauer et al [14]. These ruminant tFA are intermediates in the microbial biohydrogenation of PUFA during fermentation by the rumen intestinal microbiota resulting generally in a low t9/t11 index in dairy products (<1) [18]. CLA are isomers of LA with conjugated double bonds in trans and cis configurations which are converted, for example, from LA via the biohydrogenation process.…”

Effect of micro-alga supplementation on goat and cow milk fatty acid composition

“…Throughout biohydrogenation rumenic acid is formed from linoleic acid in the rumen by anaerobic bacteria (such as Butyrivibrio fibrisolvens), with vaccenic acid (t11C18:1) as intermediates. The vaccenic acid is converted to rumenic acid by Δ 9 -desaturase in mammary gland and also in some human tissues (Kuhnt et al, 2006). Some authors reported that diet can exert influence on rumenic acid concentration in milk, such as high protein level (Czauderna et al, 2010) and supplemental sunflower fat (Martínez et al, 2012).…”