Sodium glutamate alters lifespan, stress resistance and metabolism in Drosophila

Background. Sodium glutamate (SG) is a widely used flavor enhancer that is regularly consumed by many people worldwide. Despite its widespread use, the safety of SG remains a subject of debate, as existing experimental studies report conflicting results. Additional research is necessary to better understand its biological effects. In this study, we investigated the impact of SG consumption on lifespan, stress resistance, feeding behavior, and metabolism in the fruit fly Drosophila melanogaster. Materials and Methods. To assess physiological and biochemical parameters, flies were reared for 15 days on a control diet or food supplemented with SG. Lifespan, resistance to oxidative stress and starvation, and feeding rate were assessed. In addition, we analyzed the levels of key metabolites, including glucose, glycogen, and triacylglycerides, to evaluate the metabolic consequences of SG intake. Results and Discussion. We showed that consumption of food supplemented with a low concentration of SG (0.1%) increased the lifespan of male flies. However, high concentrations of dietary SG decreased the survival of flies of both sexes. Consumption of SG increased resistance to oxidative stress in females, whereas it decreased resis­tance to starvation. SG leads to higher overall food consumption in flies if the level of dietary SG is low. Consumption of food supplemented with SG affected carbohydrate and lipid metabolism. We observed a decrease in triacylglycerides in flies of both sexes under SG treatment. However, the effects of SG on glucose and glycogen contents were gender-specific. Conclusion. SG influences lifespan in a sex-specific and dose-dependent manner. Excessive intake significantly alters physiological traits in Drosophila, including metabolism. Specifically, dietary SG reduced body glycogen levels in males but increased it in females, while triglyceride levels decreased in both sexes under SG treatment, indicating improved lipid utilization. These findings highlight distinct sex-based metabolic responses to SG consumption.