Conjugated linoleic acid rapidly reduces body fat content in mice without affecting energy intake

Abstract

Recent reports have demonstrated that conjugated linoleic acid (CLA) has effects on body fat accumulation. In our previous work, CLA reduced body fat accumulation in mice fed either a high-fat or low-fat diet. Although CLA feeding reduced energy intake, the results suggested that some of the metabolic effects were not a consequence of the reduced food intake. We therefore undertook a study to determine a dose of CLA that would have effects on body composition without affecting energy intake. Five doses of CLA (0.0, 0.25, 0.50, 0.75, and 1.0% by weight) were studied in AKR/J male mice ( n = 12/group; age, 39 days) maintained on a high-fat diet (%fat 45 kcal). Energy intake was not suppressed by any CLA dose. Body fat was significantly lower in the 0.50, 0.75, and 1.0% CLA groups compared with controls. The retroperitoneal depot was most sensitive to the effects of CLA, whereas the epididymal depot was relatively resistant. Higher doses of CLA also significantly increased carcass protein content. A time-course study of the effects of 1% CLA on body composition showed reductions in fat pad weights within 2 wk and continued throughout 12 wk of CLA feeding. In conclusion, CLA feeding produces a rapid, marked decrease in fat accumulation, and an increase in protein accumulation, at relatively low doses without any major effects on food intake.

Dietary conjugated linoleic acid has limited effects on tissue protein anabolism in sedentary and exercising adult rats

“…In other studies, CLA increased body protein concentration or lean body percentage without modification of absolute amounts, in mice [13][14][15], rats [16] and humans [17,18]. It has also been shown to increase lean mass, protein levels and muscle mass in mice [19][20][21], rats [22], pigs [23] and humans [1,24,25].…”

“…This extra time was not allowed for in the calculation of incorporation time. In vivo fractional synthesis rates (FSR, %.d −1 ) of tissue proteins were calculated according to the following: FSR = 100 × (EP-EN)/(EA × t) where EP and EA are the 13 C enrichments of protein-bound valine and of free valine respectively, at the end of the incorporation time. EN is an estimation of the natural 13 C enrichment of protein-bound valine (before flooding dose injection); it was determined in 4 additional rats fed the same diets as the experimental rats.…”

The effect of trans-10,cis-12 conjugated linoleic acid on lipogenesis is tissue dependent in hamsters

“…The reduction that we found in the mRNA expression of these transcriptional factors, induced by trans-10,cis-12, paralleled changes observed in ACC and FAS. Concerning the effects of CLA on liver, several studies in mice have shown that trans-10,cis-12 increased liver weight [8][9][10][11][12][13]. In some of these trials, hepatic triacylglycerol content was measured and it was concluded that hepatomegaly was due to lipid accumulation [5,[14][15][16].…”

Conjugated linoleic acid isomers modulate protein expression profile in rat hepatocytes

“…It seems that t10,c12 CLA isomer, and not the CLA mixture, is responsible for the increased insulin resistance, fasting blood glucose levels, and dislipidemia in humans (Riserus et al 2002b). The insulin resistance may be induced by an enhancement of oxidative stress (Riserus et al 2002b) or by an increase in the lipolytic rate and free fatty acid levels associated with supplementation (DeLany et al 1999). There are evidences, as much from studies on rats as on humans, that this isomer probably promotes liver hypertrophy and insulin resistance through redistribution of body fat (Riserus et al 2002a).…”