Glycaemic Response to High REsistant STarch Bread

In an attempt to increase dietary fibre intake, research has focused on developing wheat-based food products with novel fibres and starches to complement fibre intake from whole grain foods. Resistant starch is starch that escapes digestion in the small intestine and may be fermented in the large intestine by the microbiota. Resistant starch is a type of dietary fibre and it is normally found in wheat-based foods made from refined flour but only in small amounts. White bread made from sbeIIa/b wheat, which has high levels of resistant starch (a type of fibre), is showing promise in modulating blood glucose response and increasing satiety compared with conventional white bread.

The primary aim of this study is to determine whether consumption of sbeIIa/b white bread at breakfast, gives rise to a lower postprandial blood glucose response compared with consumption of a reference white bread in healthy individuals.

Additional aims of the study include: determining whether consumption of sbeIIa/b white bread by healthy subjects, gives rise to a lower glucose concentration in interstitial fluid, as measured by a Continuous Glucose Monitoring system (CGM), compared with consumption of control white bread; and exploring satiety and energy intake changes in healthy individuals following consumption of sbeIIa/b white bread at breakfast, compared with consumption of control white bread.

Inclusion criteria

• Men and women
• Aged 18 to 65 years
• BMI between 18-25 kg/m2
• Non-smokers
• Those that live within a 40-mile radius of Norwich

Exclusion criteria

• Fasting glucose >6.1 mmol/L and/or HbA1c>42 mmol/mol, as assessed by a fasting blood test
• Eligibility screening results indicate they are not suitable to take part in this study
• Smokers (if they have smoked within the 6 weeks prior to the study or during the study)
• Suffer from allergy, intolerance, or sensitivity to gluten, yeast or any of the food ingredients used in this study
• Have a known allergy to adhesives that would prevent proper attachment of the Continuous Glucose Monitoring sensors
• Are pregnant and/or have been pregnant in the last year or are lactating and/or breastfeeding
• Are currently suffering from, or have ever suffered from eating disorders, any diagnosed gastrointestinal disease, gastrointestinal disorders including regular diarrhoea and constipation (excluding hiatus hernia unless symptomatic) or other inflammatory diseases like rheumatoid arthritis (RA), polymyalgia rheumatica or other connective tissues diseases
• Have undergone gastrointestinal surgery; this will be assessed on an individual basis
• Have been diagnosed with diabetes, anaemia as this may affect the study outcome
• Have been diagnosed with any long-term medical condition that may affect the study outcome (e.g. cardiovascular diseases, cancer)
• Regularly take over-the-counter medications for digestive/gastrointestinal conditions
• Use medications likely to interfere with energy metabolism, appetite regulation and hormonal balance, including long-term steroids, antibiotics. They may be able to participate if 4 weeks or more have passed from the end of a course such medication
• Regularly take laxatives (once a month or more) as this may affect blood glucose levels
• Take certain dietary supplements or herbal remedies and are unwilling to stop taking them (if required) for two weeks prior to and during the study period
• Are on, or plan to start, a diet programme that may affect the study outcome (e.g. 5:2 fasting diet) unless willing to abstain for 1 month prior to and during the study period
• Went through a weight change of ≥ 3kg in the preceding 2 months
• Have a recent history of substance abuse
• Regularly consume more than 14 units of alcohol a week
• Are unwilling to suspend smoking and vaping for the duration of the study.
• Are participating in another research project that involves dietary intervention or blood sampling.
• Are unwilling to provide GPs contact details
• Are related to or living with any member of the study team.
• Are unable to provide written informed consent
• Have not donated blood or taken part in another dietary intervention in the last 16 weeks and are unwilling to wait until 16 weeks have elapsed
• Those with abnormal blood pressure measurements