Designer foods target microbiome to boost host health

Researchers have developed foods designed to alter the gut microbiome, with an eye toward moving the needle on two immense public health challenges: malnutrition and obesity. These conditions represent opposite types of energy imbalance that co-exist in our modern world, sometimes within the same household. Decades of research has documented how the state of the community of microbes that inhabit the gut, or gut microbiome, reflects their human host’s health. The gut microbiome also changes in response to dietary components that are metabolized by specific microbial species, such as fiber. Two recent studies explored the impacts of foods customized to shape the gut microbial landscape in children with malnutrition and adults with obesity.

One study represented the latest in an ongoing series of investigations supported by NIDDK, the Bill and Melinda Gates Foundation, and others of microbiome- based dietary interventions in malnourished children in Bangladesh. These children show signs of an immature gut microbiome for their age, which in turn impacts their response to therapeutic food interventions. Previously, this group of researchers from the United States and the International Centre for Diarrhoeal Disease Research, Dhaka, designed a “microbiota-directed complementary food,” or “MDCF,” containing flours and oils from nutrient-dense, locally available foods such as chickpeas, nuts, and bananas. In the most recent study, they compared the effects of their MDCF with the standard ready-to-use supplementary food given to malnourished children. Bangladeshi girls and boys ages 12 to 18 months with moderate malnutrition received either the standard supplementary food or MDCF twice daily for 3 months, and were monitored for changes in growth, levels of proteins linked to growth and neural development, and gut microbial species present. The results demonstrated that the MDCF dietary supplement not only supported a more age-appropriate gut microbiome, but also resulted in greater improvements in growth and markers of neural development in these children, compared to those given the standard ready-to-use supplementary food.

In another study, the scientists aimed to design snacks containing plant-based fiber to promote beneficial microbial responses in adults with overweight/obesity. Beginning with an animal model, male mice raised in a sterile environment free of microbes were colonized with gut microbes from women with obesity. The mice were then fed a fiber-deficient, high-fat diet supplemented sequentially with plant fiber from either peas, oranges, or barley. Over time, the abundance of microbial genetic material present in the stool increased dramatically for the enzymes needed to break down each unique fiber, and for microbial species that are associated with protecting against obesity such as Bacteroides. Pilot clinical trials tested whether this effect was translatable to people. Men and women with overweight/obesity were given prepared meals of a fiber-deficient, high-fat diet similar in nutritional composition to the one fed to the mice, supplemented with a snack composed of pea fiber, for several weeks. Similar to the results in mice, the study participants showed the same shift in microbial gene abundance toward a ramped up metabolic capacity for fiber. Follow-up studies testing snacks composed of multiple types of plant-based fibers, including those used in the mouse studies, demonstrated an even greater microbial shift towards fiber metabolism. Consumption of the extra fiber in snacks was also associated with altered protein profiles in participants’ blood, indicating impacts on diverse physiological responses, such as metabolism and immune function. These findings provide compelling evidence of the strong connections among the gut microbiome, nutrition, and health impacts, and for the utility of mouse models of human response to food-based interventions that target the microbiome.