Effects of Adulterated and Re-used Cooking Fat on Metabolic Syndrome in Male Sprague Dawley Rats (Rattusnorvegicus)

Abstract

Globally, metabolic syndrome (MetS) has been on the rise and yet its risk factors are diverse in different populations. In most low income estates of major Kenyan cities and towns, roadside eating establishments reuse their both their cooking fats and oils in an attempt to minimize their businesses operating expenses. Some unscrupulous businessmen mix cooking fat with transformer oil to extend its cooking life: this over exposure of cooking fat to high temperatures and adulteration results in consumption of highly unstable oxidized and contaminated fats. The extended exposure to these abused fats poses a health risk and its physiological and toxic effects may have far reaching public health implications. The consumption of foods fried in these fats can possibly have an adverse effects to the body’s immune system and subsequentlyexacerbatelong term conditions like HIV/AIDS, tuberculosis and cancers and other non-communicable diseases. This study aimed to explore the effects of transformer oil-adulterated and reused cooking fats on the metabolic syndrome in male Sprague Dawley rats (Rattusnorvegicus). Using a randomized experimental design, twenty four (24) weaned male Sprague Dawley rats were assigned to four (4) groups (n=6): ND, as control group I (fed a standard rat diet ad libitum), HFD, group II (fed 20% high fat diet ad libitum), RHFD, group III (fed 20% reused high fat diet) and group IV, RHFD + T.O, (fed a mixture of 20% reused high fat and transformer oil diet in the ratio of 3V:1V).To minimize on the expenses, measurementswere undertaken at the end of the study period but not monitored over time. The groupsmean body weights in grams were compared at the end of the study period as well as fastingblood sugar after 12 hours of fasting the experimental animals. After an intraperitoneal injection of Insulin,blood sugar was xiv established at T0, T30, T60 and T120 and their mean of area under curve (AUC) usedas a measure insulin tolerance. Venous blood was also collected at the end of the study period by a standard retro-orbital puncture for liver enzymes, lipid profile and osmotic fragility of the red blood cells assays. The study animals were then sacrificed and groups liver to body weight ratios determined. Finally the harvested liver samples were fixed in 10% neutral buffered formal saline (40% formaldehyde, 9% sodium chloride) and processed for Histopathology. The experimental data were analyzed using One-way ANOVA followed by suitable post-hoc comparison performed using the statistical software Prism version 6.00 for Windows (GraphPad Software, La Jolla California USA). The significance level was set at p<0.05. As compared to other study groups, group IV (RHFD+T.O diet) results hada significantly elevated osmotic fragility of the red blood cells of 108.8 ± 16.7 % at 0.34%NaCl, (p = 0.0043) as compared to the ND group, liver weight to body weight ratio was highest between RHFD + T.O and HFD groups (p = 0.0043), elevatedliver enzyme ALT between RHFD + T.O and HFD groups (p = 0.0043), and a lipid disorder. Additionally, the same group had a significantly reduced body weight as compared to HFD, (p = 0.0087) with acute liver necrosis and significant portal inflammation of 2 according to theNon-alcoholic Steatohepatitis Clinical Research Network Histological grading system, indicating liver toxicity and bad health. Group III (20% RHFD) study animals were highly indicative of Non-alcoholic Steatohepatitis-inflammation of the liver concurrent with fat accumulation; the liver histology showed fat accumulation, inflammation, and fibrosis in different stages, this results were not well demonstrated in other study groups.Overall results further showed that all the groups on 20% high fat diet presented with differing levels of lipid disorders. These findings demonstrate the hazardous effects of reused cooking fats and transformer oil mixtures and recommends for further studiesand surveys on commercial use of cooking fats and oils in Kenya.