Defatted Soya Flour Supplementation of Wheat Bread Confers Oxidative, Renal, Hepatic and Cardiovascular Protective Effects in Wistar Rats

Background: The present study was designed to ascertain the effect of supplementation of bread with defatted soy flour on antioxidant, renal, hepatic and cardiovascular status in Wistar rats.

Methods: Hard wheat flour was mixed with high quality defatted soy flour at several ratios: 90:10(w/w), 80:20(w/w), 70:30(w/w), and 60:40 (w/w). The respective ratios of the flour mixtures were mixed with other ingredients and used to bake the wheat-soy bread. The 100% hard wheat flour baked bread was the control. All bread samples were tested for both chemical and sensory characteristics. Forty Wistar rats were randomly given codes and allocated to 5 different groups via tables with random numbers to feed on the 100% wheat breads and soy supplemented bread groups respectively for 28 days and sacrificed using cervical dislocation. Blood was collected through ocular puncture and used for biochemical assays while liver was used for antioxidant assay.

Results: There was a significant (p<0.05) increase in the liver levels of antioxidant enzymes: reduced glutathione (GSH),superoxide dismutase (SOD) and catalase (CAT) enzymes in experimental rats liver of wheat-soy bread groups compared to the control group and a significant (p<0.05) reduction in wheat-soy bread groups for lipid peroxidation-malondialdehyde (MAL) compared to non-supplemented group. However, antioxidant enzymes and lipid peroxidation biomarker levels of the wheat-soy bread groups were not significantly (p>0.05) different from one another. There was a significant (p<0.05) reduction in the serum levels of liver enzymes namely: Aspartate Transaminase (AST), Alanine Transaminase (ALT) and Alanine Phosphatase (ALP) as well as serum levels of lipid biomarkers namely: Low Density Lipoproteins (LDL), Cholesterol (CHOL) and Triglycerides (TG) in wheat-soy bread groups as compared to the wheat bread group (control). However, the serum levels of these lipid biomarkers in all the four wheat-soy bread experimental rat groups were not significantly (p>0.05) different from one another. The serum levels of renal function markers (Total Bilirubin, Creatinine and Urea) as well as protein markers (Total Protein and Albumin) were significantly (p<0.05) lower in wheat-soy bread experimental rat groups compared to wheat bread group but were not significantly (p>0.05) different for the wheat-soy supplemented groups.

Conclusion: Our findings establish the nutritional and health promoting benefits of soy supplemented bread. In addition, it was also deduced that 10% wheat-soy bread gave the bread the best overall quality acceptability.