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A new UK study explores how the physical structure of food plays a key role in how the human body digests it, highlighting opportunities for manufacturers to develop foods with less adverse health effects.

The research team, from the Quadram Institute in Norwich and Imperial College London, have published their paper in the journal Nature Metabolism.

They demonstrated that foods made with chickpea flour, prepared in a way that keeps the plant cells intact, triggered a much healthier metabolic response during digestion than nutritionally identical foods made with milled flour.

While ultra-processed foods (UPFs) have increasingly been linked to a rise in diet-related health conditions, the term is not tightly defined. Many of these UPFs are also high in known risk factors for diseases like fats, sugars and salt.

The impact that processing itself plays on the microstructure of food, and how this impacts digestion and the release of nutrients and sugars into the blood, is ‘often overlooked,’ the researchers said.

They noted that this changes how the body responds with signalling hormones. Pharmaceuticals that mimic these hormones have shown success for weight management and diabetes.

In their study, the researchers designed porridge meals made from chickpeas that were nutritionally identical, apart from how the chickpeas themselves were processed.

In one porridge, the chickpeas had been processed, breaking down the natural cellular structure, as happens when making conventional chickpea flour. In the other, a different process was used to ensure cells remained intact.

Previous studies in laboratory models of digestion have shown how preserving the intact cell structure protects the cells’ contents from attack by digestive enzymes, slowing down their breakdown and the release of sugars.

In humans, this would be expected to trigger the gut hormone feedback system to signal that the body is full and reduce appetite.

The new pilot study showed evidence of this feedback mechanism in action. Ten healthy adult participants were each fitted with two enteral feeding tubes to enable the collection of samples from their stomach and upper small intestine, every 15 minutes over an 180-minute period, for four days at the NIHR Imperial Clinical Research Facility.

This process measured how food was digested and how it influenced gut metabolites. Blood samples were also collected to measure blood sugar, insulin and gut hormones involved in regulating satiety. The ten volunteers ate porridge meals made with either broken or intact cell chickpea flour.

The porridge made with the extensively processed ‘broken cell’ chickpeas was digested more rapidly and increased the glucose peak in the participants’ blood two to four times more than porridge made with intact chickpea cells.

In contrast, the porridge made with intact cells was digested more slowly and produced a prolonged release of the appetite-suppressing hormones GLP-1 and PYY. The participants also reported higher feelings of fullness.

The Quadram Institute’s Cathrina Edwards, corresponding author of the study, said: “Although the foods in the study would have the same food label, because they contain the same ingredients and nutrient composition, we’ve shown how processing-induced changes to the structure leads to significant effects on hormone and blood sugar responses”.

With this in mind, the team highlighted that simple changes to processing that consider structure could deliver foods consumers still enjoy, but which avoid some of the negative health effects associated with intensive processing and keep consumers feeling satisfied for longer.

First author Mingzhu Cai, of Imperial College London’s Department of Metabolism, Digestion and Reproduction, explained: “There’s a lot of discussion at present about GLP-1 agonists such as Ozempic. While natural levels of GLP-1 will never reach that level of pharmaceutical dose, by understanding how and where it is released, we have a better chance of increasing the doses that our bodies can produce.”

The study was supported by the Biotechnology and Biological Science Research Council, part of UK Research and Innovation.

A spin-out company, PulseOn Foods, is now developing a patent-protected flour for commercial use, containing high proportions of intact cells, using an alternative milling process.

Gary Frost, chair in nutrition and dietetics at Imperial College London, said: “Changing food structures could ultimately help to protect the population from chronic diseases such as type two diabetes, and that’s why this research is so exciting. It’s all building up the knowledge in this area which will be essential for improving foods in the future.”