Dietary CLA Combined with Palm Oil or Ovine Fat Differentially Influences Fatty Acid Deposition in Tissues of Obese Zucker Rats

The effect of conjugated linoleic acids on inflammation, oxidative stress, body composition and physical performance: a comprehensive review of putative molecular mechanisms

Conjugated linoleic acids (CLAs) are polyunsaturated fatty acids primarily found in dairy products and ruminant animal products such as beef, lamb, and butter. Supplementation of CLAs has recently become popular among athletes due to the variety of health-promoting effects, including improvements in physical performance. Preclinical and some clinical studies have shown that CLAs can reduce inflammation and oxidative stress and favorably modulate body composition and physical performance; however, the results of previously published clinical trials are mixed. Here, we performed a comprehensive review of previously published clinical trials that assessed the role of CLAs in modulating inflammation, oxidative stress, body composition, and select indices of physical performance, emphasizing the molecular mechanisms governing these changes. The findings of our review demonstrate that the effect of supplementation with CLAs on inflammation and oxidative stress is controversial, but this supplement can decrease body fat mass and increase physical performance. Future well-designed randomized clinical trials are warranted to determine the effectiveness of (1) specific doses of CLAs; (2) different dosing durations of CLAs; (3) various CLA isomers, and the exact molecular mechanisms by which CLAs positively influence oxidative stress, inflammation, body composition, and physical performance.

A multifunctional ingredient for the management of metabolic syndrome in cafeteria diet-fed rats

The body weight-lowering properties of a multifunctional ingredient (MIX) based on conjugated linoleic acid at low doses, the flavonoids proanthocyanidins and anthocyanidins and the chicken feet hydrolysate Hpp11 have been previously reported. The aim of this study was to evaluate the effect of long-term administration of MIX on other cardiometabolic risk factors associated with metabolic syndrome (MetS) in rats fed a cafeteria diet (CAF). Male Wistar rats were fed CAF for 11 weeks, and during the last 3 weeks, animals were orally administered MIX or vehicle. Lipid tolerance tests were performed before and after MIX administration. At the end of the experimental period, serum and inguinal white adipose tissue (iWAT) metabolism were analyzed by metabolomics and biochemical approaches. The metabolite signature of serum and iWAT significantly changed after 3 weeks of MIX administration, suggesting an improvement in lipid and glucose homeostasis in these animals. In addition, MIX also exhibited significant antihypertensive properties. These results suggest that MIX could be a good candidate to ameliorate the cardiometabolic risk factors related to MetS.

Effects of dietary CLA on n-3 HUFA score and N-acylethanolamides biosynthesis in the liver of obese Zucker rats

We have recently shown that PPAR alpha agonists induce N-oleoylethanolamide (OEA) and N-palmitoylethanolamide (PEA) biosynthesis. Conjugated linoleic acid (CLA), a known dietary PPAR alpha inducer, may therefore increase OEA and PEA levels and favor docosahexaenoic acid (DHA) biosynthesis by enhancing peroxisomal β-oxidation via induction of liver PPARα. To evaluate whether CLA is able to increase DHA, OEA and PEA levels and thereby influencing liver lipid deposition in a model of visceral obesity-induced fatty liver, Zucker rats were fed a background diet rich in saturated fat with or without 1% of CLA for 4 weeks. Our data showed that CLA intake increased DHA, OEA and PEA levels in the liver by 24%, 31% and 36% respectively, and reduced hepatic lipid accumulation by 16%. We may conclude that dietary CLA is able to influence not only fatty acid metabolism but also the biosynthesis of bioactive mediators such as OEA and PEA which may contribute to ameliorate fatty liver.

Mice do not accumulate muscle lipid in response to dietary conjugated linoleic acid

Dietary CLA decreases body fat in several species and in pigs this is accompanied by increased muscle lipid. Our objective was to determine if mice could be used as a model for CLA-induced increased marbling in pigs. We used our model of enhanced CLA response, where mice fed coconut oil (CO) lose more body fat than mice fed soy oil (SO). Mice (21 d old; Imprinting Control Region [ICR]) were fed SO or CO diets for 6 wk followed by 12 d of 0 or 0.5% mixed isomer CLA. Ether extraction determined that thigh muscle lipid content was reduced by both CLA and CO (P = 0.007 and P = 0.006, respectively). Conjugated linoleic acid also caused a reduction (P = 0.016) in carnitine palmitoyltransferase (CPT) enzyme activity, so less fatty acid oxidation appeared to be occurring. Lumbar muscle, which is more similar to the longissimus dorsi tested in pigs, did not differ in lipid content between mice (56 d old; ICR) fed SO or SO+CLA for 14 d. Therefore, CLA-fed mice do not appear to be accumulating excess lipid in their muscle. However, CLA addition to CO diets increased (P = 0.007) the mRNA expression of PPAR-γ in the thigh muscle to the level of SO-fed mice, indicating that intramuscular adipocyte differentiation may be increasing. On the other hand, liver lipid was increased (P < 0.0001) by CO and tended to be increased (P = 0.099) by CLA. Liver CPT activity was decreased (P = 0.018) in SO+CLA-fed mice but not CO+CLA. It appears that mice may accumulate lipid in their livers preferentially over muscle when fed CLA and therefore are not a good model for CLA-induced muscle lipid accumulation.