Insects are a viable protein source for human consumption: from insect protein digestion to postprandial muscle protein synthesis in vivo in humans: a double-blind randomized trial

BACKGROUND: Insects have recently been identified as a more sustainable protein-dense food source and may represent a viable alternative to conventional animal-derived proteins. OBJECTIVES: We aimed to compare the impacts of ingesting lesser mealworm– and milk-derived protein on protein digestion and amino acid absorption kinetics, postprandial skeletal muscle protein synthesis rates, and the incorporation of dietary protein–derived amino acids into de novo muscle protein at rest and during recovery from exercise in vivo in humans. METHODS: In this double-blind randomized controlled trial, 24 healthy, young men ingested 30 g specifically produced, intrinsically l-[1-(13)C]-phenylalanine and l-[1-(13)C]-leucine labeled lesser mealworm– or milk-derived protein after a unilateral bout of resistance-type exercise. Primed continuous l-[ring-(2)H(5)]-phenylalanine, l-[ring-3,5-(2)H(2)]-tyrosine, and l-[1-(13)C]-leucine infusions were applied, with frequent collection of blood and muscle tissue samples. RESULTS: A total of 73% ± 7% and 77% ± 7% of the lesser mealworm and milk protein–derived phenylalanine was released into the circulation during the 5 h postprandial period, respectively, with no significant differences between groups (P < 0.05). Muscle protein synthesis rates increased after both lesser mealworm and milk protein concentrate ingestion from 0.025 ± 0.008%/h to 0.045 ± 0.017%/h and 0.028 ± 0.010%/h to 0.056 ± 0.012%/h at rest and from 0.025 ± 0.012%/h to 0.059 ± 0.015%/h and 0.026 ± 0.009%/h to 0.073 ± 0.020%/h after exercise, respectively (all P < 0.05), with no differences between groups (both P > 0.05). Incorporation of mealworm and milk protein-derived l-[1-(13)C]-phenylalanine into de novo muscle protein was greater after exercise than at rest (P < 0.05), with no differences between groups (P > 0.05). CONCLUSIONS: Ingestion of a meal-like amount of lesser mealworm–derived protein is followed by rapid protein digestion and amino acid absorption and increases muscle protein synthesis rates both at rest and during recovery from exercise. The postprandial protein handling of lesser mealworm does not differ from ingesting an equivalent amount of milk protein concentrate in vivo in humans. This trial was registered at www.trialregister.nl as NL6897.