Effects of rye and whole wheat versus refined cereal foods on metabolic risk factors: a randomised controlled two-centre intervention study

Abstract

Background & aims: Intervention studies investigating the effects of wholegrain intake on glucose and insulin metabolism have provided conflicting results. Aim of this study was the evaluation of glucose and insulin metabolism in response to long-term consumption of rye and whole wheat compared with a diet containing the same amount of refined cereal foods, in individuals with metabolic syndrome from two European locations (Kuopio-Finland/Naples-Italy).

Methods: 146 individuals of both genders, age range 40-65 years with metabolic syndrome, were recruited to this study with parallel groups. After a 2-4 week run-in period, participants were assigned to a diet based on wholegrain (wholegrain group) or on refined cereal products (control group), each one for a duration of 12 weeks. Peripheral insulin sensitivity, assessed by FSIGT, lipids and inflammatory markers were measured before and at the end of intervention.

Results: 61 participants in the control group and 62 in the wholegrain group completed the dietary intervention. Compliance to the two diets was good. At the end of the intervention, insulin sensitivity indices and secretion (SI, QUICKI, DI, dAIRG) and lipids and inflammatory markers did not change significantly in the wholegrain and control groups as compared with baseline and no differences between the two groups were observed.

Conclusions: Wholegrain cereal foods consumption compared with refined cereals for 12 weeks did not affect peripheral insulin sensitivity. The study was registered with ClinicalTrials.gov identifier NCT00945854.

Trial registration: ClinicalTrials.gov NCT01020617.

Keywords: ARs; BIA; CVD; Cereal fibre; DI; FSIGT; GI; Glucose metabolism; IFG; IGT; IL-1ra; IL-6; Inflammatory markers; Insulin sensitivity; Metabolic syndrome; OGTT; QUICKI; S(I); TNF-α; Wholegrain; alkylresorcinol homologues; bioelectrical impedance analysis; cardiovascular disease; dAIRG; disposition index; dynamic glucose-stimulated insulin response; frequently sampled intravenous glucose tolerance test; glycaemic index; high sensitivity C-reactive protein; hs-CRP; impaired fasting glucose; impaired glucose tolerance; index of fasting insulin sensitivity; insulin sensitivity index; interleukin 1 receptor antagonist; interleukin 6; oral glucose tolerance test; tumour necrosis factor-α.