This brief report summarises a framework for understanding satiety presented at the 13th European Nutrition Conference, FENS 2019 – Malnutrition in an Obese World: European Perspectives. Aspects of satiety phenotyping and role of food hedonics in satiation are considered in the context of appetite control and obesity. Almonds are evaluated for their unique composition and structure which affect their behaviour in the human gastrointestinal tract. Their role in appetite control and management of satiety has been explored.

Epidemiological and clinical evidence highlight the benefit of dietary fibre consumption on body weight. This benefit is partly attributed to the interaction of dietary fibre with the gut microbiota. Dietary fibre possesses a complex food structure which resists digestion in the upper gut and therefore reaches the distal gut where it becomes available for bacterial fermentation. This process yields SCFA which stimulate the release of appetite-suppressing hormones glucagon-like peptide-1 and peptide YY. Food structures can further enhance the delivery of fermentable substrates to the distal gut by protecting the intracellular nutrients during upper gastrointestinal digestion. Domestic and industrial processing can disturb these food structures that act like barriers towards digestive enzymes. This leads to more digestible products that are better absorbed in the upper gut. As a result, less resistant material (fibre) and intracellular nutrients may reach the distal gut, thus reducing substrates for bacterial fermentation and its subsequent benefits on the host metabolism including appetite suppression. Understanding this link is essential for the design of diets and food products that can promote appetite suppression and act as a successful strategy towards obesity management. This article reviews the current evidence in the interplay between food structure, bacterial fermentation and appetite control.

The positive effects of dietary fibre on health are now widely recognised; however, our understanding of the mechanisms involved in producing such benefits remains unclear. There are even uncertainties about how dietary fibre in plant foods should be defined and analysed. This review attempts to clarify the confusion regarding the mechanisms of action of dietary fibre and deals with current knowledge on the wide variety of dietary fibre materials, comprising mainly of NSP that are not digested by enzymes of the gastrointestinal (GI) tract. These non-digestible materials range from intact cell walls of plant tissues to individual polysaccharide solutions often used in mechanistic studies. We discuss how the structure and properties of fibre are affected during food processing and how this can impact on nutrient digestibility. Dietary fibre can have multiple effects on GI function, including GI transit time and increased digesta viscosity, thereby affecting flow and mixing behaviour. Moreover, cell wall encapsulation influences macronutrient digestibility through limited access to digestive enzymes and/or substrate and product release. Moreover, encapsulation of starch can limit the extent of gelatinisation during hydrothermal processing of plant foods. Emphasis is placed on the effects of diverse forms of fibre on rates and extents of starch and lipid digestion, and how it is important that a better understanding of such interactions with respect to the physiology and biochemistry of digestion is needed. In conclusion, we point to areas of further investigation that are expected to contribute to realisation of the full potential of dietary fibre on health and well-being of humans.

Bread is one of the most widely consumed staple foods worldwide. White-wheat bread, largely consumed in France, is made from highly refined flour, which leads to a low nutrient density. Due to a highly porous structure and gelatinised starch, it is easily broken down during digestion, leading to a rapid increase of glucose released into the bloodstream. Low glycaemic responses are considered favourable to health, especially against a background of diabetes. Literature reports show that selection of raw material is an essential factor in decreasing the glycaemic index (GI) of white bread. There are two means of decreasing the rate of starch degradation: either (i) slowing gastric emptying rate and/or glucose diffusion–absorption through the intestinal mucosa, which can be achieved by incorporating soluble fibre or organic acid in bread, or (ii) limiting starch accessibility to α-amylase by using high-amylose cereal varieties and/or incorporating intact cereal grains. Studies on cereal products show that preservation of the food structure during digestion seems to be a more important GI-reducing factor than the degree of starch crystallinity or the presence of soluble fibre. Thus, we should look to produce bread with a more compact food structure or higher density, which is the case in leavened wholewheat bread or bread with intact cereal grains. The baking process should also be improved to achieve this goal, by using, for example, a reduced kneading time or less yeast than usual.

Previous research indicates that vegetables yield relatively high satiety scores, and that fibre content and structure may both contribute to these effects. This study evaluated the effects of the fibre content and physical structure (gross anatomy and cell structure) of carrots on postprandial satiety and subsequent food intakes when consumed as part of a mixed meal. Using a randomised, repeated-measures, within-subject cross-over design, young women consumed a standardised breakfast and test lunches on three occasions, 4 weeks apart. The test lunches (3329kJ) comprised boiled rice (200g) with sweet and sour sauce (200g) that included chicken (200g) and carrots (200g) in three conditions: whole carrots (fibre and structure; n 34), blended carrots (fibre but no structure; n 34) or carrot nutrients (no fibre or structure; n 32). The carrot nutrients had the same energy, major nutrients and portion weight as the other two conditions. Post-lunch satiety was assessed by visual analogue scales. Intakes were covertly weighed at a meal eaten ad libitum (3h later), and for the remainder of the day using food diaries. Compared with the meal with carrot nutrients, meals with whole carrots and blended carrots resulted in significantly (P<0·05) higher satiety. There were significant (P<0·05) differences between conditions in intakes at the meal eaten ad libitum and for the remainder of the day, and intakes consistently decreased in the order: carrot nutrients, blended carrots, whole carrots, indicating that both fibre content and structure played a role in these effects.