Effect of Dietary Fibre and Whole Grain on the Metabolic Syndrome

Sedentary lifestyles and increasing obesity are main causes of the global increase in the prevalence of the metabolic syndrome (Mets) and type 2 diabetic (T2DM). Diet quality, particularly composition of carbohydrate play also a significant role. The glycemic index (GI) describes in relative terms rise of blood glucose after ingestion of carbohydrate-rich food. Purified dietary fibre as β-glucan (BG) has been shown to reduce GI and affect levels of satiety hormones. In contrast, our knowledge of the physiological effects of arabinoxylans (AX), which constitute a substantial part of dietary fibre in cereal products, is limited. The investigators also lack a deeper understanding of the importance of whole grain (whole grain with whole kernels, and purified dietary fibre) in relation to Mets and T2DM.

Hypothesis: The composition of dietary carbohydrates can be designed so that they improve the glycemic and insulinaemic responses and increase satiety feeling. This can be detected in metabolic parameters in subjects with Mets.

The aim of our study is in subjects with Mets to compare the effect of acute consumption of bread rich in (a) purified AX, (b) purified BG, (c) rye bread with whole kernels (RK), with a (d) control group with consumption of white bread (WB).

The primary endpoint is GI. Secondary endpoints are the following items: glycemic load, insulin index, glucose, insulin, glucagon, inflammatory markers, incretins, rate of gastric emptying, and metabolomics. Also satiety feeling will be measured.

This project will improve opportunities for identifying and designing foods with low GI that is particularly suited to people who are at high risk of developing T2DM. The investigators also expect to gain a greater understanding of the metabolic fingerprint, as seen after ingestion of low-GI foods and thereby gain a molecular understanding of how low-GI foods affect health by altering metabolic processes. This will give us a deeper insight into the metabolic processes that are necessary for maintaining normal glucose homeostasis.

Using a cross-over design, 12 subjects with Mets will consume test meals containing the four different bread types. Blood samples will be collected over 4,5 hours after ingestion of test meals containing around 145 g of each bread type, equivalent to 50 g available carbohydrate and 3 dl + 2 dl water on four different days in randomized order. Visual Analog Scale (VAS) will be used for determination of subjective satiety feeling and a subsequent meal will be served to estimate prospective food consumption.

• Experimental: Beta-glucan
  Bread with purified beta-glucan
  Intervention: Other: Bread types
• Experimental: Rye kernels
  Rye bread with kernels
  Intervention: Other: Bread types
• Experimental: White bread
  White bread
  Intervention: Other: Bread types
• Experimental: Arabinoxylan
  Bread with Purified arabinoxylan
  Intervention: Other: Bread types

Inclusion Criteria:

• central obesity (Female > 94 cm; Male > 80 cm) with two of the following: -- fasting triglyceride (> 1,7 mmol/L)

  • HDL-cholesterol: (Female: < 1,03 mmol/L; Male: < 1,29 mmol/L)
  • blood pressure (≥ 130/85 mmHg)
  • fasting plasma glucose (≥ 5,6 mmol/L)) Subjects who are in medical treatment with lipid and blood pressure-lowering drugs can continue with their habitual treatment provided that the treatment is stable throughout the trial.

Exclusion Criteria:

• fasting plasma glucose > 7,0 mmol/l
• fasting plasma triglyceride > 5,0 mmol/l
• blood pressure > 160/100 mmHg
• legal incapacity
• endocrine, cardiovascular or kidney disease
• BMI > 38kg/m2
• corticosteroid treatment
• alcohol or drug addiction
• pregnancy or lactation.