Assessing a Polydextrose Containing Soup on Food Intake, Appetite and Biomarkers of Satiation and Satiety

This study will examine the impact of a soluble fibre (polydextrose) incorporated into a high fibre tomato soup on food intake (amount and choice), appetite ratings and biomarkers of satiation and satiety over 4-weeks. Specifically, the impact on the development of satiation within the fixed-load tomato soup containing the fibre, the development of satiety after the fixed-load meal containing fibre and intake at subsequent ad libitum meals will be examined as well as the insulin response and carbohydrate fermentation before and after 4-week dosing of the preload soup.

The science underpinning both short (episodic) and long (tonic) term appetite regulation demonstrates that foods higher in macronutrients such as fibre can, under certain experimental conditions, produce great decreases in feelings of hunger and increases in fullness, post consumption, compared to equi-caloric loads of high carbohydrate or high fat. Given that fibre increases the release of GLP-1, slows down gastric emptying, prolongs nutrient absorption and, over long-term use increases the generation of short chain fatty acids (SCFAs) which have been linked to improved satiety responding, it is plausible that it will produce strong effects on within meal processes of satiation and satiety over the short- and long-term. Fibre has also been suggested to influence carbohydrate fermentation (via generation of these SCFAs) and improve the insulin response, additionally improving satiety. Ingredients may be added to boost fibre content such as the use of polydextrose, which is a non-digestible polysaccharide usually used as a dietary fibre in foods. Polydextrose has also been shown to increase levels of SCFAs due to its slow fermentation and has been related to reductions in subsequent intake and/or reduced hunger.

The aim of the current study is to assess the impact of a high fibre, polydextrose enriched tomato soup (experimental) or a low fibre tomato soup (control) on food intake, the experience of appetite and biomarkers of satiation and satiety.

Sample size: 86 males aged between 18 and 55 years with a body mass index (BMI) of between 23.0 and 28.0 kg/m2. A subset of 28 participants will undergo additional finger prick blood glucose and hydrogen breath test measures to assess biomarkers of satiation and satiety. Power calculations to ensure sufficient participants are included were based on power expected for a medium effect (0.25) at 80% power for a 2 condition between-measures design using G\*power.

Methods: Participants will be invited to three full test day (baseline control, session 1; first dosing, session 2; one day prior to final dosing, session 3) sessions in which they will be provided with breakfast (tailored to individual resting metabolic rate (RMR) using the Schofield equation), the preload condition (receiving a high fibre polydextrose enriched or control tomato soup) one hour before an ad-libitum lunch and followed four hours later by an ad-libitum dinner and snack box. All test days will involve the use of standard operating proceedures. Pre-packaged portions of soup will be provided for a 4-week dosing period between study sessions 2 and 3 for all participants.

A subset of participants (N=28) will additionally undergo 3 further testing sessions (baseline control, session 0; second dosing, session 3; final dosing, session 4) in which a breakfast will be provided followed by the test product with additional glucose and carbohydrate fermentation measures collected for 3 hours before a light fixed portion meal.

Throughout test days participants will complete visual analogue scales (VAS) for appetite and palatability as well as questionnaires pertaining to eating behaviour and current sensations (including a gastrointestinal distress questionnaire).

Statistical analysis: Primary analysis will be comparison of subsequent ad-libitum energy intake between high fibre polydextrose enriched tomato soup compared to control using ANOVA and post-hoc tests. Meal duration and various appetite ratings will also be analysed as will biomarkers of satiety. The specified participant numbers (n=86) give an 80% probability of detecting an effect on energy intake.

Eligibility Criteria:
Inclusion Criteria:

* BMI of 23-28 kg/m2
* Not dieting within the last month and not having lost significant amount of weight in the previous year.
* Not increased physical activity levels in the past 2-4 weeks or intending to modify them during the study
* Able to eat most everyday foods
* Breakfast eaters
* Soup consumers
* Written informed consent to be given

Exclusion Criteria:

* Those with significant health problems
* BMI \< 23.0 kg/m2 or \> 28.0 kg/m2
* Participants who self-report dieting currently or within the last month or having lost a significant amount of weight over the previous 6 months.
* Volunteers who have significantly changed their physical activity patterns in the past 2-4 weeks or who intend to change them during the study
* Gastrointestinal symptoms requiring treatment.
* Smokers or those who have recently ceased smoking (including electric cigarettes).
* Participants receiving systemic or local treatment likely to interfere with evaluation of the study parameters.
* Participants who work in the following areas: Nutrition, Dietetics, Food Research, Food Manufacturing or Supplements Industry.
* Participants currently adhering to any specific food avoidance diets such as Atkins, the South Beach diet or low Glycaemic Index (GI).
* Participants who have had bariatric surgery for weight control or other reason.
* Non breakfast eaters.
* Those reporting a history of anaphylaxis to food, significant general food allergies or specific allergies to any of the study foods.
* Participants with abnormal eating behaviour