Effect of long-term consumption of aspartame on body weight, blood glucose, lipid profile, and kidney and liver fuction in rats

Background and objective: Aspartame (L-aspartyl L-phenylalanine-1- methyl ester) (APM) is the most widely used nonnutritive synthetic sweetener added to a wide variety of food products and drugs that are consumed by about 70% of the population. Based on the available studies, the data concerned on its effects on health and problems that may arise after its consumption remain controversial .This study was planned in order to shed a light on how chronic consumption of APM may affect important biochemical parameters as body weight, total protein, albumin, blood glucose, lipid profile, aminotransferases, and biomarkers of oxidative stress focusing in catalase in liver, brain 8-OHdG and urinary isoprostane and kidney functions (creatinine and uric acid).
Methods: Male Wistar rats were divided randomly into four groups: Group 1 as control and groups 2, 3 and 4 treated with aspartame at 20, 40 and 80 mg/kg respectively during four months. Samples of blood for measure (total protein, albumin, glucose, lipid profile, ALT, AST, LDH, creatinine, and uric acid), catalase in liver, brain 8-OHdG and urine (isoprostane) were collected every 8 weeks to proceed the evaluation.
Results: Administration of APM significantly affected all the studied parameters in all doses tested. After 4 months of treatment with APM at 40 and 80 mg/kg, respectively, there was an increased level of the following parameters: blood glucose (21 and 25) %, total cholesterol (23 and 42)%, triglycerides (24 and 55)%, LDL- cholesterol (97 and 132) %, and uric acid (53 and 48)%. The level of HDL-cholesterol was decreased around (64 and 67%. The activity of AST (36, 27 and 38) %, catalase (36, 36 and 40 % and LDH (136, 168 and 148) % were increased after 4 months of treatment at the doses of 20, 40 and 80 mg/kg, respectively. Similarly, the level of 8- OHdG (8-hydroxy-2' -deoxyguanosine), a known biomarker for oxidative stress and carcinogenesis, was increased to about (55) % after 4 months of treatment with APM at 80 mg/kg. Function of the kidney was affected by the treatment with APM during 4 months, as showed by the significant increase in creatinine (20, 104 and 31) % at 20, 40 and 80 mg/kg. Finally, level of urinary isoprostane, a prostaglandin-like compound produced by the free radical mediated peroxidation of lipoproteins, was also elevated.
Conclusion: the administration of APM during 4 months showed a deleterious effect on the kidneys and liver function. Besides that, a combination of atherosclerotic effects were also observed, as well as, a general increased exposure to oxidative stress, as demonstrated through the 8-OHdG and Urinary isoprostane levels elevation. The sweetener consumption increased the liver lipoperoxidation and the risk of carcinogenesis. The kidney’s function was also affected. Therefore, APM was considered unsafe to be included in the diet. Taken together, these results suggest that the long-term consumption of APM may be harmful in humans.