Potential health benefits of conjugated linoleic acid from natural and industrial sources. Evidences from animal studies

BERNAL, CLAUDIO; GERSTNER, CAROLINA; FARIÑA, ANA; SAIN, JULIANA; LAVANDERA, JIMENA; SCALERANDI, MV; GONZALEZ, M; ANTONACCI, LILIANA; GAGLIOSTRO, GERARDO

Ciudad Autónoma de Buenos Aires

Congreso; 21st INTERNATIONAL CONGRESS OF NUTRITION (IUNS); 2017

World food programme y Sociedad Argentina de Nutrición

Conjugated linoleic acid (CLA) is a group of positional and geometrical isomers of linoleic acid recognized by their functional properties. %e major contribution of natural CLA is supplied by dairy products and meats where c9,t11-18:2, known as rumenic acid (RA), represents 80-90% of total CLA. On the other hand, industrially synthesized commercial CLA mainly contains a mixture of equimolecular amounts of c9,t11-18:2 and t10,c12-18:2 (mix-CLA). Nutritional studies in human and experimental animals have demonstrated a variety of bene"cial health consequences from CLA consumption. However, controversial and detrimental health e!ects have also been reported. %e precise actions and the biochemical mechanisms by which CLA-rich foods mediate the metabolic e!ects remain unclear. Since the specific effects of c9,t11-18:2 and t10,c12-18:2 are di!erent, we have analyzed the e!ects of CLA from industrial and natural source on di!erent animal models or experimental conditions that share some metabolic disorders observed in the metabolic syndrome. Specifically, parameters associated with the lipid depots and glucose regulations are described. In normal mice, mix-CLA and RA-rich oil (natural-like CLA) modifed the triacylglycerol (TAG) metabolism having diferent efects depending on the type of CLA and the dietary unsaturated fatty acids (FA) proportions. The reduction of fat in carcass and adipose tissue was higher in the mix-CLA than in RA supplemented diets, independently of the dietary n-9, n-6 and n-3 FA ratio. However, RA showed benefcial effects without hepatomegaly, steatosis, or hypertriacylglyceridaemia. In mice fed high fat (HF) diets, mix-CLA reduced plasma and muscular TAG concentrations. These benefcial e!ects were associated with a protection against hepatic oxidative stress mediated by an increase in glutathione levels. Nevertheless, the biochemical mechanisms involved in the regulation of lipid levels were related to a reduced hepatic VLDL-TAG secretion and decreased muscle and adipose tissue lipoprotein lipase enzymes, leading to a liver steatosis and dystrophy of epididimal fat pads. Contrary, in a steatosis rat model induced by protein depletion, protein repletion with mix-CLA showed preventive e!ects on liver steatosis through higher VLDL-TAG secretion and reduced adipose tissue lipid accumulation. In the glucose regulation, dietary mix-CLA supplementation at HF levels partially prevented glycolytic pathway alterations in liver of mice increasing the glycogen synthesis. Glucose utilization was also investigated in isolated skeletal muscle; where in basal conditions dietary mix-CLA improved glucose uptake and incorporation as well as glycogen synthesis via an increase in glucose oxidation. Finally, We have investigated the e!ect of a functional milk fat (FMF) enriched in RA on glucose and lipid metabolism of rats fed HF diets. Noteworthy, FMF prevented the hepatic TAG accretion induced by HF diets by increasing the hepatic VLDL-TAG secretion and the b-oxidation. In addition, FMF improved the muscle glucose utilization associated with a higher flux through the phosphofructokinase enzyme. Even though the experimental results in animal models cannot be directly extrapolated to humans, knowledge of the mechanism involved in the beneficial e!ects of natural or commercial CLA, under different conditions, might be useful for the development of functional foods efective to prevent some metabolic alterations observed in human metabolic síndrome.