Incorporation of cis-9,trans-11 or trans-10,cis-12 conjugated linoleic acid into plasma and cellular lipids in healthy men

Abstract

Incorporation of cis -9, trans -11 or trans -10, cis -12 conjugated linoleic acid into plasma and cellular lipids in healthy men Abstract This study investigated the incorporation of cis -9, trans -11 conjugated linoleic acid (c9,t11 CLA) and trans -10, cis -12-CLA (t10,c12 CLA) into plasma and peripheral blood mononuclear cell (PBMC) lipids when consumed as supplements highly enriched in these isomers. Healthy men (n ‫؍‬ 49, age 31 ؎ 8 years) consumed one, two, and four capsules containing ‫ف‬ 600 mg of either c9,t11 CLA or t10,c12 CLA per capsule for sequential 8 week periods followed by a 6 week washout before consuming the alternative isomer. Both isomers were incorporated in a dosedependent manner into plasma phosphatidylcholine (PC) (c9,t11 CLA r ‫؍‬ 0.779, t10,c12 CLA r ‫؍‬ 0.738; P Ͻ 0.0001) and cholesteryl ester (CE) (c9,t11 CLA r ‫؍‬ 0.706, t10,c12 CLA r ‫؍‬ 0.788; P Ͻ 0.0001). Only t10,c12 CLA was enriched in plasma nonesterified fatty acids. Both c9,t11 CLA and t10,c12 CLA were incorporated linearly into PBMC total lipids ( r ‫؍‬ 0.285 and r ‫؍‬ 0.273, respectively; P Ͻ 0.0005). The highest concentrations of c9,t11 CLA and t10,c12 CLA in PBMC lipids were 3-to 4-fold lower than those in plasma PC and CE. These data suggest that the level of intake is a major determinant of plasma and PBMC CLA content, although PBMCs appear to incorporate both CLA isomers less readily. Conjugated linoleic acid (CLA) is a collective term for 18 carbon fatty acids that differ in the geometry and position of two conjugated double bonds. CLA occurs naturally in meat and dairy products, which are the principal sources of these fatty acids in the human diet (1). Cis -9, trans -11 (c9,t11) is the major CLA isomer in dairy products, with lesser amounts of t7,c9 Ͼ c11,t13 Ͼ c8,t10 Ͼ t10,c12 (1).A number of animal studies, primarily in rodents, show that increased consumption of CLA results in effects that may be potentially beneficial to human health (2), including antitumorigenic activity (3), decreased atherogenesis (4-6), decreased adiposity and increased lean body mass (7-9), and normalized glucose tolerance and nonesterified fatty acid (NEFA) concentration in Zucker rats (10). The effects of CLA on body composition have been attributed specifically to the activity of t10,c12 CLA (11, 12). Consumption of CLA in rodents also increased lymphocyte proliferation (13-16) and altered cytokine secretion (13)(14)(15).In contrast to studies in animal models, there is marked variation among reports on the effects of increased CLA consumption on body composition (16-21) and immune function (22-24) in humans. All studies in humans reported to date have used mixtures of CLA isomers typically containing predominantly c9,t11 CLA and t10,c12 CLA in different ratios together with smaller amounts of other isomers. These range from relatively pure preparations containing c9,t11 CLA and t10,c12 CLA in ratios of 50:50 or 80:20 (22, 25-28) to complex mixtures (23,29,30). Thus, the dose of individual isomers may be relatively low despite high in...

The effects of conjugated linoleic acid supplementation on immune function in healthy volunteers

“…These minimal detection levels are similar to that published by other groups (Mougios et al, 2001). In addition, the level of t10,c12-CLA enrichment was very variable between subjects whereby the standard deviation was almost equal to the mean values as has been demonstrated in a recent publication (Burdge et al, 2004).…”

Differential effects of conjugated linoleic acid isomers on macrophage glycerophospholipid metabolism

“…Although several groups have reported that c9,t11-CLA is metabolized in cells and incorporated into plasma and tissue lipids ( 15,28 ), only a few studies investigated its effects on cellular lipids. Metabolism of t9,t11 -CLA and its contribution to cellular lipids is completely unexplored.…”

“…Concerning CLA metabolism, it has been shown that c9,t11 -CLA incorporates into phospholipids of leukemia cells and can be found in plasma and cellular lipids of healthy men supplemented with a diet enriched with this CLA isomer ( 14,15 ). However, so far the effects of c9,t11 -CLA on individual phospholipid classes, phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), and its cellular distribution are not precisely described, and data on the metabolism of the t9,t11 -CLA isomer are completely unavailable.…”

The effects of conjugated linoleic acid on human health-related outcomes

“…273 respectively; P < 0 . 0005) when consumed in the diet (Burdge et al 2004). No evidence was found for differential incorporation of these isomers into PBMC, although the final concentration of each isomer was reported to be markedly lower than that in plasma phosphatidylcholine and cholesteryl ester fractions at each dose (Burdge et al 2004).…”