Influence of dietary fats on serum phospholipid fatty acid composition and its relation to obesity in animals

Abstract

Dietary fat and its relation to obesity has been a controversial issue for many years. Experimental data shows that most, though not all animals, which consume a high fat diet, will become obese. However, the effect of fatty acids on animal obesity has not been studied in detail. In order to evaluate the effects of low versus high fat diet on serum phospholipids fatty acids composition a 4-wk study was conducted on male Wister rats. The rats were fed low-fat (10% energy) and high-fat (46% energy) foods containing constant proportions of fatty acids. Control group C was fed a standard laboratory diet (polyunsaturated/ saturated (P/S) fatty ratio 1.3), group M was fed a standard laboratory diet supplemented with margarine (P/S ratio 0.95), and the diet of the SL group was additionally supplemented with a sunflower oil-lard (1:1) mixture (P/S ratio 1.3). All lipid supplemented hyperenergetic diets caused an increase in the average daily energy intake. Both the final and the daily body weight gain were significantly higher in M and SL groups than in group C. Additionally, serum triglyceride levels, LDL-cholesterol and total cholesterol were also significantly higher in M and SL groups when compared to the control group. Serum phospholipids fatty acids varied in response to total dietary fat. A significant decrease in saturated fatty acids (SFA) content (16:0 and 18:0) and an increase in monounsaturated fatty acid (MUFA) content (18:1, n-9) was found in the M group when compared to both C and SL groups. In the SL group, SFA content (18:0) was higher and MUFA content (18:1, n-9) was lower than in group C. Polyunsaturated fatty acids (PUFA) content showed an increase in both experimental groups. The PUFA/SFA ratio was higher in the M group than in the C and SL groups. Our study suggests that the amount of dietary fat has a greater influence on obesity than the effects of the type of fat consumed. However, depending on the type of fat present in the diet the differences were observed in the composition of serum PL fatty acid suggesting that both total fat and individual fatty acids have to be considered when reaching conclusions about the effect of dietary fat and obesity in animals