Comparative Effects of Co-Ingesting Whey Protein and Glucose Alone and Combined on Blood Glucose, Plasma Insulin and Glucagon Concentrations in Younger and Older Men
What this study found
Co-ingesting whey protein with glucose substantially blunted postprandial glycemia in both younger and older men, and the glucose-lowering effect was preserved with aging. Compared with glucose alone, whey protein plus glucose reduced the postprandial blood glucose rise by 44 ± 38% over 3 h, with reductions of 50 ± 13% in the first hour and 66 ± 33% in the second hour, all significant. The combined drink also produced a more than additive insulin response, with Net iAUC 0-180 min of 28.3 ± 4.7 vs 21.3 ± 3.2 mU/L * min for whey protein plus glucose versus the sum of the individual drinks (p =…
- Study & population
- Randomized, double-blind, crossover study in healthy men, with separate younger and older groups.
- Intervention
- Participants received oral test drinks on four randomized crossover occasions: 30 g glucose monohydrate, 30 g whey protein, 30 g whey protein plus 30 g glucose, or flavored water as control.
- Key limitation
- Small acute crossover study with only 20 healthy male participants, limiting precision and generalizability.
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Open PDFOriginal abstract
The ingestion of dietary protein with, or before, carbohydrate may be a useful strategy to reduce postprandial hyperglycemia, but its effect in older people, who have an increased predisposition for type 2 diabetes, has not been clarified. Blood glucose, plasma insulin and glucagon concentrations were measured for 180 min following a drink containing either glucose (120 kcal), whey-protein (120 kcal), whey-protein plus glucose (240 kcal) or control (~2 kcal) in healthy younger (n = 10, 29 ± 2 years; 26.1 ± 0.4 kg/m2) and older men (n = 10, 78 ± 2 years; 27.3 ± 1.4 kg/m2). Mixed model analysis was used. In both age groups the co-ingestion of protein with glucose (i) markedly reduced the increase in blood glucose concentrations following glucose ingestion alone (p < 0.001) and (ii) had a synergistic effect on the increase in insulin concentrations (p = 0.002). Peak insulin concentrations after protein were unaffected by ageing, whereas insulin levels after glucose were lower in older than younger men (p < 0.05) and peak insulin concentrations were higher after glucose than protein in younger (p < 0.001) but not older men. Glucagon concentrations were unaffected by age. We conclude that the ability of whey-protein to reduce carbohydrate-induced postprandial hyperglycemia is retained in older men and that protein supplementation may be a useful strategy in the prevention and management of type 2 diabetes in older people.