Developing Foods for Enhanced Satiety - Understanding Food-Gut-Brain Interactions
Published on 11 February 2013 in Food, health and wellbeing
Introduction
Currently, dietary rather than pharmacological approaches are being sought to prevent weight gain, aid weight loss and maintain a lower and healthy weight. Many different diets appear almost every week in popular magazines and especially just after Christmas, but few are effective in the long term. The most effective are those where attention has been given to the diet composition rather than just the energy value or calories. Individual foods are made up of 3 primary macronutrients, these being protein, carbohydrate and fat. These are also known to have a hierarchical impact on satiety, or the feeling of fullness, where protein is most satiating, followed by carbohydrate and then fat.
When the most effective macronutrient-adjusted diet is provided and adhered to, participants tend to lose approximately 1kg per week, with significant improvements in body composition, blood pressure and biomarkers of health as a result of the weight loss. Such diets are associated with better fat loss and also relatively less lean mass loss. However, most of the weight loss and associated health benefits of these diets, and indeed most dietary regimes, that are seen at 6 months, are usually lost by 12 months. This is mainly due to poor compliance or drop out from the diets and then weight regain is usually seen. Encouragingly, there is some evidence of greater compliance and sustained weight loss with lower drop out rates from high protein diets.
Macronutrient-induced satiety could, therefore, set the foundation for dietary manipulation aimed at improving long-term health benefits. Additive or synergistic effects also may be seen with combinations of the most satiating constituents such as protein and fibre (see earlier briefing – Dietary Fibre and Satiety). Results should potentially lead to informed selection of dietary ingredients and development of nutritional strategies, including the reformulation of food, that reduce incidences of obesity and greatly aid long term, sustainable weight loss.
A number of nutrient sensing receptors exist in the gut, and these are thought to play a role in sensing macronutrient levels in the gut. The pathway to satiety begins with release of hormones found in specific receptor expressing cells of the gut. Once released these gut hormones bring on the satiated state through mechanisms that involve signalling via nervous communication or via blood circulation to appetite centres of the brain. Our main area of interest is in how diets with specific macronutrient contents are able to influence the release of these gut hormones which signal satiety to the brain, with a view to aid reformulation of food to achieve enhanced satiety value.
Key Points
- We need to be able to assay and investigate the mechanism underpinning the satiating responses of different macronutrients.
- We need a fuller understanding of the responses of gut nutrient sensing receptors that are involved in signalling macronutrient-stimulated satiety to the brain.
- We need a scientific evidence base to establish the type and quantity of macronutrients that induce satiety sufficiently to give effective reductions in appetite and food intake.
This should allow us to provide dietary advice of how best to use elevated satiety as a natural physiological approach for appetite suppression and long term healthy weight management.
Research Undertaken
Our research approach involves the study of macronutrient-induced satiety where we aim to identify responses of dietary compounds in cultured cell models that express nutrient sensing receptors. This work has led to the identification of a number of cell types that are useful model systems for testing the responsiveness to specific nutrients in terms of intracellular signalling and release of gut hormones.
Complimentary work is being conducted in controlled animal model environments where the relative amounts of macronutrient in a diet can be tested over time with animals of differing ages, from juvenile to adult. With state of the art technology we are able to scan and monitor over time, any changes in body composition induced by the different diet compositions. This will lead to investigations of the underlying molecular systems that cause elevated levels of gut hormones involved in signalling meal termination and extending the between-meal time before re-feeding.
Policy Implications
It is anticipated that if the work is successful, then we should be able to provide evidence that certain dietary macronutrients or combinations will be more effective in increasing satiety in animal models. This data will then be validated in humans before it could be released as advice to the general public, and/or as product formulation advice to the food industry aimed at healthy weight management.
Authors
Dr Alexander Ross A.Ross@abdn.ac.uk
Dr Perry Barrett P.Barrett@abdn.ac.uk
