Annette Rivera

University of Rhode Island

Dietetics


1999

Mentor: Dr. Anthony Tagliaferro, Professor of Animal and Nutritional Sciences

The effects of conjugated linoleic acid on adipose development and energy metabolism

Experimental evidence has shown that a natural derivative of linoleic acid, called conjugated linoleic acid (CLA), has health benefits in protecting against many chronic diseases including coronary heart disease, cancer and obesity. In laboratory mice, it has been shown that when CLA is added to the diet, there was a dramatic change in body composition that involved an increase in fat free mass and decrease in fat mass. The present study examined the effects of dietary CLA on energy and substrate metabolism by indirect calorimetry and fat tissue development using four month old female Yucatan miniature swine from two separate litters. During the first two weeks of the study (baseline period) the animals were adapted to the experimental conditions; energy metabolism of the animals was measured and blood samples were taken. At the end of baseline, the animals from each litter were assigned equally and randomly to either an experimental (Exp.) or a control (Con.) condition. The Con. and Exp. swine were fed iscocalorically (100 Kcal/kg), a commercial swine chow/ corn oil mixture (weight for weight 1.5%) or chow (1% corn oil, 0.5% CLA mixture), respectively. The blood samples taken at baseline and during weeks 3 and 6 of the experiment were to measure hormone and substrate (fatty acids and triglycerides) levels. During weeks 5-6, animals underwent metabolic testing and a backfat biopsy was taken to measure fat cell size and fat cell metabolism. Using ultrasound and deuterated water methods, subcutaneous adiposity and total fat, respectively, were also measured. At baseline, the mean body weights of the Exp. and Con. animals were similar. However, the rate of energy expenditure (energy production per kg body wt) of the Exp. vs Con. animals was 19% lower (P < 0.0001). Consistent with these baseline findings, initial backfat thickness of the Exp. animals was 81% higher than the Con. (P <0.005). It remains to be seen whether the initial differences in energy metabolism and growth of backfat between Exp. and Con. animals will be modified by the CLA treatment.

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