Antioxidant effect of amaranth flour or protein isolate incorporated in high-fat diets fed to Wistar rats. Influence of dose and administration duration

This study evaluated the effect on Wistar rat's oxidative status of incorporating amaranth flour (AF) and protein isolate (AI) in increased-fat diets. Five of the groups were fed for 4 weeks with either BD (basal diet), Chol+F (2% cholesterol, 10% porcine fat), Chol+F+E (0.005% alpha-tocopherol), Chol+F+AF(1) or Chol+F+AI(1) (25% of protein replacement) diets. The other two groups were fed for 4 weeks with Chol+F and then 1 week with Chol+F+AF(2) or Chol+F+AI(2) diet (50% of protein replacement). Various effects on the oxidative stress biomarkers in tissues (intestine and liver) were observed. These effects were dependent on the ingredients, dose, and administration time. In the intestinal cells, Chol+F+AF(1) and Chol+F+AI(2) produced an increment in the reduced glutathione (GSH) content (56% and 39%, respectively), while Chol+F+AF(2) induced an increment in the superoxide dismutase (SOD) (25%) and glutathione peroxidase (GPx) (46%) activities. The presence of certain components in flour (e.g., fiber, polyphenols, squalene) could explain the higher activity recorded for AF. In the liver, Chol+F+AF(2) produced a decrease in SOD (19%) and GSH (36%), as well as an increase in GPx (255%); Chol+F+AI(1) and Chol+F+AI(2) also produced a decrease in GSH (36% and 24%, respectively) and important increments in GPx activity (273% for Chol+F+AI(1) and 2,900% for Chol+F+AI(2)). These effects were dependent on the AI dose and were probably produced by absorbed peptides. Practical applications It is known that redox imbalances are involved in the genesis of many chronic diseases. Therefore, it is possible to prevent them or limit their severity by improving the body's antioxidant defense mechanisms through dietary incorporation of antioxidant substances. The results suggest that amaranth protein isolate and amaranth flour have the potential for regulating intestinal and liver cells redox balance; effects were more evident when they contributed 50% of the diet's protein content and were administered for 1 week. Both amaranth ingredients could be used as ingredients in the development of functional foods with beneficial antioxidant properties.

Automated summary

The study showed that incorporating amaranth flour and protein isolate in rat diets could regulate the redox balance in intestinal and liver cells, especially when they made up 50% of the protein content in the diet and were administered for 1 week. These two amaranth ingredients have the potential for developing functional foods with beneficial antioxidant properties.