Edible insect migratory locust Locusta migratoria) is not only an alternative protein resource but also a potential candidate for improving agent of lipid metabolism

Background and objectives: The world's population is estimated to reach 9.7 billion by 2050. This growing global population will require available resources to meet the nutritional needs of human health. Edible insects are increasingly recommended as novel sustainable food resources for human, but their nutritional and functional properties have not been fully evaluated. Migratory locust (Locusta migratoria), a representative edible insect, has been recognized as a novel food material by the European Food Safety Authority on 2021. If nutritional and functional properties are more clarified, migratory locust is expected to be developed as valuable and sustainable food resources. We have clarified that the migratory locust powder (MLP) contained rich in proteins, n-3 lipids (triglycerides and several kinds of phospholipids with α-linolenic acid), polyphenols, and indigestible fiber chitin, which are improving lipid metabolism. Here, dietary effects of MLP on lipid metabolism were investigated in rats. Methods: The MLP, which was produced in Thailand and commercially sold in Japan, was used for the study. The 5-weeks-old male Wistar rats were fed with the casein (AIN-93G containing 20% protein and 7% fat) or MLP diet for 5 weeks. The MLP diet contained 10% MLP in AIN-93G diet. Growth efficiency and nutritional and biochemical parameters in the plasma, liver, and adipose tissues were investigated. Results: Dietary MLP represented the favorable growth and improvement effect on hepatic lipid metabolism. Dietary MLP suppressed plasma lipid levels and low-density-lipoprotein (LDL) levels by upregulating liver LDL-receptor expression and suppressing proprotein convertase subtilisin kexin 9 (PCSK9) activity. Dietary MLP also altered fatty acid profile in the plasma, liver, and adipose and suppressed plasma arteriosclerosis-related factors. Additionally, dietary MLP downregulated the liver de novo lipogenic protein expressions and enzyme activities, leading to the improvement of liver function related factors. These findings can be comparable to the effects of statin, a dyslipidemia improving agent. N-3 lipids among several kinds of functional ingredients in MLP are mainly considered to contribute to the improvement of hepatic lipid metabolism. Conclusions: MLP is expected as valuable and sustainable food protein and lipid resources with functionality and safety.