Dietary Bioactive Components
Objectives : Red raspberries (RRB) contain a unique polyphenol profile associated with cardio-metabolic benefits. Fructo-oligosaccharides (FOS), as prebiotics, present an approach to augment the cardio-metabolic benefits of RRB through their known effects in modifying the gut microbiota composition. The objective of this study is to determine the effect of RRB intake with or without FOS on glucose and insulin responses and fasting lipid profile in insulin-resistant (IR) (n = 20) and metabolically healthy reference (R) adults (n = 11) in a single-blinded, randomized, 12-week crossover clinical trial.
Methods : In this crossover study, after one-week run-in, subjects consumed RRB (1 cup RRB equivalence) or RRB+FOS (1 cup RRB equivalence with 8g FOS) for 4 weeks in random order separated by 4-week washout between supplementation periods. Before and after each supplementation period, glucose and insulin responses were assessed by 2-h postprandial glycemic challenge with RRB (75 g glucose equivalence) and the plasma lipid profile characterized (total cholesterol (TC), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL) and triglycerides (TG)).
Results : IR group had significantly elevated fasting and postprandial glucose and insulin, and higher fasting TG and lower HDL compared to R at baseline (0-week) (P≤0.05); no differences in TC and LDL between groups (P >0.05). After 4-week intervention, RRB decreased TC and LDL of IR group from baseline by 7% (P=0.024) and 9% (P=0.007), respectively, whereas adding FOS significantly attenuated the lipid-lowering effect of RRB. Alternatively,addingFOS to RRB augmented RRB effect on glycemic variables: 4-week intake of RRB+FOS significantly decreased 30 min incremental areas under curve (iAUC 0-30 ) of IR group for glucose and insulin from baseline by 20% (P=0.014) and 18% (P=0.012), respectively.
Conclusions : 4-week RRB intervention improves glycemic and lipid profiles in people with IR. Adding FOS to RRB supplement enhanced the glycemic benefits, but attenuated the lipid-lowering effect of RRB.
Funding Sources : This work was supported by the National Processed Raspberry Council.