Background:
Insects have been identified as a sustainable source of high-quality protein and may represent a more sustainable alternative to conventional animal-based proteins. So far, there are no data on postprandial protein handling of insect protein.

Aim:
To assess mealworm protein digestion and amino acid absorption kinetics and the subsequent postprandial muscle protein synthetic response following mealworm and milk protein ingestion at rest and during recovery from exercise in vivo in humans.

Methods:
In this double-blind randomized parallel-group trial, 24 healthy young males ingested 30g specifically produced, intrinsically L-[1-¹³C]-phenylalanine and L-[1-¹³C]-leucine labeled, mealworm or milk protein following a single bout of unilateral resistance-type exercise. Primed continuous L-[ring-²H₅]-phenylalanine, L-[ring-²H₂]-tyrosine, and L-[1-¹³C]-leucine infusions were applied, with frequent collection of blood and muscle samples. Data were analyzed using repeated measures ANOVA with Time (postabsorptive vs postprandial) and Leg (exercise vs rest) as within-, and Treatment (mealworm vs milk) as between-subjects factors. Data represent means±SD.

Results:
A total of 73±7% and 77±7% of the mealworm and milk protein-derived phenylalanine appeared in the circulation during the 5h postprandial period, respectively, with no differences between treatments (P=0.263). Muscle protein synthesis rates increased from 0.025±0.008 and 0.028±0.010 %/h in the post-absorptive state to 0.045±0.017 and 0.056±0.012 %/h following mealworm and milk protein ingestion at rest, respectively (P<0.001), with no differences between treatments (P=0.089). Postprandial muscle protein synthesis rates were higher in the exercised compared to the resting leg (P<0.001), and reached 0.059±0.015 and 0.073±0.020 %/h following mealworm and milk protein ingestion, respectively (P<0.001), with no differences between treatments (P=0.088).

Conclusion:
Mealworm protein ingestion is followed by rapid protein digestion and amino acid absorption and a substantial increase in muscle protein synthesis rates both at rest and following exercise. The postprandial protein handling of mealworm protein does not differ from milk protein in healthy young males.