Gut appeal: Healthy microbiome thanks to food processing waste

15 Feb 2019 --- New research from Maastricht University (UM) has uncovered a novel use for waste from the food processing industry: boosting the microbiome. Using the TNO in vitro model of the colon (TIM-2), research by Carlota Bussolo de Souza has shown that fermenting fiber from fruit and vegetable peel can help improve the gut flora of people with obesity.

Bussolo de Souza’s research uncovered that fermenting fiber from by-products of the fruit and vegetable sector can boost the level of butyric acid, the healthiest type of metabolite, in the intestines of overweight people. This metabolite has been shown not only to protect against bowel cancer but also to play a vital role in energy and fat metabolism.

Bussolo de Souza’s research was conducted at the UM campus in Venlo, the Netherlands, where she used the TIM models in the lab of Professor Koen Venema.

Venema tells NutritionInsight that the concept of studying the role of fibers and other functional food components on the gut microbiota in relation to health and disease is a central theme in the research of his group at UM campus Venlo, in the Centre for Healthy Eating & Food Innovation (HEFI).

This research, Venema notes, shows that the by-products of food processing can still be valuable because they “very likely contain bioactive components such as antioxidants and fibers. They can be valorized into functional foods, possibly contributing to a reduction in modern diseases, such as obesity.”

Research model
TIM-2 is a multi-compartmental model that closely simulates conditions in the human intestines.  Since her research received Brazilian funding, Bussolo de Souza focused specifically on waste from certain fruit and vegetable processing plants in Brazil, where this is an important sector. She collected peel from cassava, oranges and passion fruit, which was ground into powder and fed into the artificial gut at Maastricht University to uncover their gut microbiome potential.

As part of the research, feces from healthy people was fed into one model, the other from people with obesity. Overweight people generally host a less thriving bacterial population, both in bacterial amount and variety, in their gut than slim people do. 

The researchers fed the artificial intestines on a diet of waste from the Brazilian fruit and vegetable processing industry. This proved to have a particularly positive effect on the microbiota in people with obesity.

“It’s probably the specific combination of fiber from the peel that has a positive effect on gut flora in overweight people,” Professor Venema explains. “However, you should see this as a supplement to a healthy diet with lots of fruit and vegetables, not as a replacement.”

Venema notes that since the data were obtained in a validated in vitro model of the colon, they need to be validated in a human clinical trial. 

“Also, more types of fibers can be screened for their potential function in the in vitro model,” he tells NutritionInsight. “Moreover, (and this was also a question during the Ph.D.,  defense) we would like to study mixtures of fibers, of the ones we studied and of others that have been studied before or can be added based on future experiments.”

“We can expect differences from other fruit and vegetable industry from Brazil than the by-products that we tested in this research. That means that also differences are expected using waste from other countries.”

“It would be great if French fry and potato chip producers could use their waste to contribute to the fight against the obesity epidemic and the increase in related conditions such as Type 2 diabetes or cardiovascular disease,” Venema muses. “Research would be needed because potatoes were outside the scope of this study.”

A renewed focus on fiber
A rise in consumer interest, regulation changes and clinical evidence on gut health and the microbiome have led to an NPD surge for the fiber market.

According to a study published in The Lancet earlier this year, higher intake levels of dietary fiber and whole grains are linked with a lower risk of non-communicable diseases, body weight and cholesterol levels. The research highlighted the importance of carbohydrate quality in our diets, which may be particularly salient as low carb diets continue to trend. “We understood fiber to be good for us, but we didn't realize just how good it is,” study author, Andrew Reynolds of the University of Otago, New Zealand, tells NutritionInsight. 

As well as mounting evidence on fiber’s health halo, the regulatory environment in the US has potentially opened NPD doors for the nutrient. According to an article published in the December edition of The World of Food Ingredients, a driving factor for the recent fiber revival was the regulatory green light of eight specific fibers by the US FDA of June last year. The update means that the promoted fibers can be classified as “dietary fibers” on the upcoming Nutrition Facts Label in the US. This move, according to industry experts, means “innovation in the fiber space can finally commence again.”

By Lucy Gunn