A novel macroalgae protein concentrate attenuates postprandial glycaemia in healthy adults.

Palmaria palmata (dulse) is a marine-derived, sustainable, protein source. Dulse protein concentrates (DPC) stimulate incretin secretion and attenuate postprandial glycaemia in preclinical models, but the effect in humans has not been characterised. We aimed to investigate the potential of a novel DPC to reduce postprandial blood glucose concentrations. Six healthy adults (age 44±18 y; body mass 72.4±12.0 kg) consumed a beverage containing 0.6 g·kg -1 body mass maltodextrin with either a high (H-DPC; 0.150 g protein·kg -1 ), low (L-DPC; 0.075 g protein·kg -1 ), or no DPC (CON), in a double blind, randomised cross-over design. Blood samples were collected at baseline and up to 120 min post-ingestion. Plasma glucose, insulin, C-peptide, glucagon, active gastric inhibitory polypeptide (GIP), and active glucagon-like peptide-1 (GLP-1) were analysed and expressed as incremental area under the curve (iAUC) and time-course responses. β-cell function parameters were derived from glucose and C-peptide modelling, to explore potential mechanisms of action of DPC. Glucose concentration was 1.28±2.35 and 1.30±3.00 mmol⋅L -1 lower for H-DPC (post hoc P =0.010) and L-DPC (post hoc P =0.008), respectively, compared to CON, 45 min post beverage consumption. Glucose iAUC differed between conditions (H-DPC: 265±135; L-DPC: 228±108; CON: 380±203 mmol⋅L -1 min; P =0.038), and was significantly lower in L-DPC versus CON (post-hoc P =0.028). Glucagon concentration was greater throughout H-DPC trial ( P =0.021). Both H-DPC and L-DPC increased GIP concentration at 15 min ( P <0.007). Insulin and GLP-1 concentrations, and β-cell glucose sensitivity did not differ between conditions. Dulse protein concentrate reduces postprandial glycaemia in healthy adults, showing potential as a sustainable dietary intervention for supporting glucose control.