Conjugated linoleic acid, geese, growth, lipid metabolism, fatty acid composition

from: http://www.ajol.info/index.php/sajas/article/viewFile/4103/38292

Conjugated linoleic acid, geese, growth, lipid metabolism, fatty acid composition

Conjugated linoleic acid (CLA) is a term used to describe positional and geometric isomers of linoleic acid (18:2n-6; LA). The two main naturally occurring isomers are cis-9, trans-11 and trans-10, cis-12. These compounds occur particularly in dairy products and ruminant meat, such as beef and lamb, but are present at lower concentrations in many foodstuffs (Chin et al., 1992; Pariza et al., 2001).
Conjugated linoleic acid has received much attention over the past decade because of its multiple biological effects. Among them, these fatty acids have been shown to reduce body fat accumulation (Badinga et al., 2003; Yamasaki et al., 2003; Wang & Jones, 2004), to improve feed efficiency (Li & Watkins, 1998) in several rodent models and to lower blood lipids and atherogenic risk in animal studies. Indeed, early work demonstrated that CLA reduces adiposity in growing mice, where 6-week old ICR mice were fed a diet containing less than 1% CLA for 28-32 days (Park et al., 1997). Further work in various animal models confirmed those findings (Delany et al., 1999). Feeding non-obese mice with CLA reduced fat mass in some depots, specifically retroperitoneal and epididymal white adipose tissue masses and brown adipose tissue (Tsuboyama-Kasaoka et al., 2000), suggesting that they are more sensitive to CLA-mediated effects. In addition, when feeding rabbits with atherogenic diets the CLA mixtures resulted in less early aortic atherosclerosis (Lee et al., 1994) or in regression of preexisting atherosclerosis (Kritchevsky et al., 2000). Feeding different levels of CLA to hamsters led to lower total plasma cholesterol, low density lipoprotein cholesterol (LDL-C) and triglyceride concentrations (Nicolosi et al., 1997). Proposed anti-obesity mechanisms of CLA include decreased energy/food intake and increased energy expenditure (Ohnuki et al., 2001; Terpstra et al., 2002), decreased pre-adipocyte differentiation and proliferation (Evans et al., 2002), decreased lipogenesis (Brown et al., 2001; Oku et al., 2003) and increased lipolysis and fatty acid oxidation