Changes in body composition in mice during feeding and withdrawal of conjugated linoleic acid

Abstract

Two experiments were conducted. In Experiment 1, 8-wk-old mice were fed control diet or diet supplemented with 0.5% conjugated linoleic acid (CLA) to study the effect of CLA on body composition (CLA: 40.8-41.1% c-9,t-11 isomer, 43.5-44.9% t-10,c-12 isomer). The data for CLA-fed mice vs. controls described parallel but significantly distinct responses for both absolute and relative changes in body fat mass (reduced in CLA-fed mice) and for relative changes in whole body protein and whole body water (both of which were increased in CLA-fed mice). In the CLA-fed mice, the effect on whole body protein appeared to precede the reduction in body fat mass. In Experiment 2, weanling mice were fed control diet or diet supplemented with 0.5% CLA for 4 wk (test group), at which time all mice were fed control diet devoid of added CLA. The test group exhibited significantly reduced body fat and significantly enhanced whole body water relative to controls at the time of diet change. Time trends for changes in relative body composition were described by parallel lines where the test group exhibited significantly less body fat but significantly more whole body protein, whole body water, and whole body ash than controls. Tissue CLA levels declined following the withdrawal of CLA from the diet. In skeletal muscle of mice fed CLA-supplemented diet, the t-10,c-12 isomer was cleared significantly faster than the c-9,t-11 CLA isomer.

Potent inhibitory effect of trans9, trans11 isomer of conjugated linoleic acid on the growth of human colon cancer cells

“…It was later found that synthetic CLA had several beneficial effects such as anticarcinogenesis [3,4], antiatherogene [5,6], decrease of body fat [7,8], and regulation of immunological reactions [9,10].…”

Short-term Administration of Conjugated Linoleic Acid Reduces Liver Triglyceride Concentration and Phosphatidate Phosphohydrolase Activity in OLETF Rats

“…They are found in edible foods, such as ruminants meats, pasteurized dairy products, and processed cheeses (Ha et al, 1989;Chin et al, 1992). CLA exhibits several beneficial effects, such as a protective effect against cancer and heart disease (Ip et al, 1991;Ip et al, 1994;Lee et al, 1994), and reduced body fat mass in experimental animals (Park et al, 1997;West et al, 1997;Park et al, 1999). Furthermore, Houseknecht et al showed that CLA is capable of improving glucose tolerance in hyperglycemic Zucker rats (Houseknecht et al, 1998).…”

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]. The discrepancies in the results, even within a specific species, suggest that several factors such as genotype, age, diet, or physical activity may interfere with CLA effects.…”

“…Mixtures of conjugated linoleic acid isomers (CLA) were initially shown to reduce the percentage of whole body fat and/or the mass of fat pads, in mice [1] and then in rats, hamsters, pigs and hu-CLA feeding had no effect on these parameters in mice [4], rats [5][6][7][8][9][10], hamsters [9,11] and humans [12]. 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 been suggested that CLA could be most effective in reducing fat mass and increasing lean mass when combined with enhanced physical activity in humans [2] and endurance training in mice [21]. Whether or not the differential effects of CLA isomers that were reported for lipid metabolism [26,27] occur in the control of lean body mass, cannot be determined, because CLA isomer mixtures were used in all the experiments quoted above except two [1,11]. In addition, the mechanisms responsible for the effects of CLA on lean body mass are unknown, mostly because their effects on the balance between protein synthesis and degradation, which controls tissue protein content and lean body mass, have not yet been described.…”