It’s part of a new approach to weight management that considers how satiety – or fullness – affects what we eat and why.
Researchers on the EU-funded SATIN project are using a mechanical model of the digestive system to help them develop a range of pre-processed foods that could be available in supermarkets in future, including bread, juices and sodas.
‘Nobody has ever studied a satiety-based approach to weight management,’ said Professor Jason Halford, of the University of Liverpool, who coordinates SATIN. ‘We need to demonstrate that it’s a viable long-term approach – that’s hopefully what SATIN will deliver.’
The appetite-satisying foods produced by the five-year SATIN project are being tested both in the model digestive system and in six clinical trials. The human studies are testing the foods for their ability to help with weight loss and final results are expected in 2016.
‘We can increase the likelihood of success in the clinical trials by optimising the food and its ingredients in this in vitro model beforehand,’ said Prof. Halford. ‘It may be that you need to change the food structure or ingredient types, or protect a certain ingredient through encapsulation, so that it gets to where it's got to go to improve satiety,’ he said.
“‘Everyone considers food to be a major part of the obesity problem, but can we manipulate it and make it part of the solution as well?’
Gut simulator
The working model is a mechanical ‘industrial cabinet’ that simulates the different processes going on as food travels through the gastrointestinal tract. There are five reactors which imitate the digestive processes occurring in the stomach, small intestine and three parts of the large intestine. It includes physical pumping and pH control, as well as features such as mucus on the gut wall and the bacteria that adhere to it.
The components of food, as well as the food itself – such as a slice of bread – are put into the simulator and then extracted at various points in the system for testing in human cell cultures, to measure the cells’ satiety response.
‘They can be cell lines that express specific hormones related to the satiety cascade,’ said Dr Massimo Marzorati, who co-founded the lab services company ProDigest which is running the gut simulator part of the SATIN project. ‘These are the hormones that normally send signals to the brain to say, “oh, I feel full,”.’
Different foods produce different hormone responses at different parts of the gastrointestinal tract, so the aim is to deliver the right nutrient signals to the right parts of the gut to get a powerful suppression of appetite. Other indicators, such as the expansion of food in the gut, can also be measured.
The researchers hope that, given a wide enough range of satiating food options, people will be able to moderate their daily energy intake more easily than through restrictive dieting. The foods could become part of the battery of measures that help combat obesity, which is now a major public health problem in Europe.
The project will also publish a satiety cookbook for people who want to learn how to cook more filling meals at home. ‘SATIN is helping the food industry to be part of the solution, not just part of the problem,’ said Prof. Halford.
Controlling weight
Professor Julian Mercer from the University of Aberdeen, UK, is a partner on the EU-funded SATIN project, and hopes that satiety-enhancing food products can help people to control their weight. ‘Everyone considers food to be a major part of the obesity problem, but can we manipulate it and make it part of the solution as well?’ he said.
Prof. Mercer is also looking at satiety from another angle, as part of the Europe-wide Full4Health project. ‘We are interested in gut-brain communication, and how food interacts with that,’ he said. ‘The two projects sit nicely alongside each other.’
Full4Health focuses on the mechanisms behind feeling full. This includes the signals sent by nerves in the gut, how these signals are integrated in the hypothalamus - which is involved in energy balance - the interaction of the hypothalamus with the higher brain reward centres, and, ultimately, how that translates into what we decide to eat at the next meal.
A major part of the work involves testing how satiety works in volunteers in different age groups, body weights and sexes. ‘Potential ways of manipulating diet might be more effective in some strata of the population than others,’ said Prof. Mercer. ‘Ultimately we’ll be putting these people into an MRI scanner to see how their brains respond to dietary challenge.’
In the long term, a greater understanding of what makes us full could help people make better decisions about what they eat. For example, Prof. Mercer imagines that one day we could see a satiety index included on food packaging, although he said that if any such initiative were to be implemented it would be ‘a long way down the road’.
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