Longterm effects of carob pulp preparations in insoluble fiber on metabolism, body weight and leptin levels in rats

Obesity is one of the most health influencing diseases and some attention has been given to food supplements like Carob, a dietary fiber and rich in insoluble fibers and polyphenols. In short term studies, both carob fibers and polyphenols itself have been shown to exert beneficial effects on metabolic parameters (cholesterol, triglycerides). It has been hypothesized that both supplements might have weight reducing effects by increasing energy expenditure and fat utilization in humans and animals. To further investigate this, we measured the influence of both, carob pulp and polyphenols on body weight, energy expenditure, respiratory quotient and metabolic hormones in rats. In this study 24 male Wistar rats were grouped (n=8) and either a carob pulp diet (CD), a polyphenol diet (PD) or a control diet (CO) was served for 21 days ad libitum. All 3 diets were equivalent in macronutrients and caloric content. Energy expenditure (EE) and respiratory quotient (RQ) were measured for 48 hours by spirometric measurement at baseline and after the feeding period and body weight gain was monitored constantly. After the study, blood was collected. During the study no significant difference was found for the increase in body weight between groups (mean±SE: CD 59.31±5.15g, PD 54.68±13.94g and CO 49.08±10.48g; p>0.05). EE was 6.69±1.97 kcal/kg*h for PD animals, 6.73±1.63 kcal/kg*h for CD animals and 6.85±1.69 kcal/kg*h for CO animals (p>0.05). For leptin no significant differences were found among the groups: Levels were 2.97±0.6 ng/ml for CD animals, 2.62±0.78 ng/ml for PD animals and 2.74±0.64 ng/ml for CO animals. We conclude that food supplements such as carob dietary fiber and polyphenols itself have no statistically relevant effect on body weight, energy expenditure, respiratory quotient and leptin levels in rats when given over a longer period and the similar postexperimental levels of leptin make it unlikely, that consumption of dietary fibers alone is sufficient to induce profound changes in metabolic function.