Microbiome Boost: Plant microorganisms in fresh produce enhance human gut bacteria, study finds

01 Nov 2023 --- A research team from Austria has provided conclusive evidence that eating fruit and vegetables contributes to bacterial diversity in the human microbiome, which is critical to good health. The sources of bacterial diversity were not conclusive until now, however, it is known that diversity is essential to human health.

The researchers say they have now proven that plant microorganisms from fruit and vegetables contribute to the human microbiome.

“Certain bacterial genes found in fresh produce are important for human health, as they are involved in the production of vitamin B12 and short-chain fatty acids (SCFA). Vitamin B12 acts as a cofactor, aiding in multiple metabolic pathways in humans, while SCFA can help improve the integrity of the gut barrier and regulate the immune system,” Wisnu Adi Wicaksono, senior scientist at the Institute of Environmental Biotechnology, Graz University of Technology (TU Graz) and first author of the study, tells Nutrition Insight. 

“We believe that the consumption of fresh produce, such as fruits and vegetables, plays a crucial role in the connection between the human microbiome and the environmental microbiome. Fruits and vegetables contain millions of bacterial cells, some of which can inhabit our gut and contribute to the overall diversity of gut bacteria.”

Nurturing good bacteria populationsResearchers have identified how fruit and vegetable bacteria colonize the human gut.
The meta-analysis, conducted by researchers at the Institute of Environmental Biotechnology at TU Graz, demonstrates that the regularity with which a host eats fruits and vegetables influences the quantity of the bacteria in the gut, was published in Gut Microbes journal. 

The variety of plants consumed also influences the amount of fruit- and vegetable-associated bacteria in the human gut. Early childhood is the perfect time to colonize the microbiome with plant-associated bacteria. These microorganisms also have probiotic and health-promoting properties.

“Fresh produce, including its microbiome, has the potential to influence the composition of the gut microbiome. By identifying personalized diets that can modify the microbiome or the metabolites produced by the microbiome, we may be able to prevent or control disease outcomes,” says Wicaksono.

“This is particularly significant during early life when the immune system is developing. Additionally, fruits and vegetables-associated bacteria have shown promise as emerging probiotics in various applications.”

The current study’s findings suggest that eating fruit and vegetables has a positive influence on the development of the immune system in the first three years of life as the intestinal microbiome develops. Good diversity of gut bacteria benefits the body’s resilience in all phases of life.

“It simply influences everything. Diversity influences the resilience of the whole organism; higher diversity conveys more resilience,” says Gabriele Berg, head of the Institute of Environmental Biotechnology at TU Graz.

Catalog of microbiome data
The team first created a catalog of microbiome data from fruits and vegetables, allowing them to assign the bacteria of each. They then compared these with publicly available data on intestinal flora.

“A microbiome is the totality of all microorganisms that colonize a macro-organism (human, animal and plant) or a part of it, for example, the intestine or a fruit. While the individual microbiomes are becoming better understood, little is known about their connections,” explains Wicakson. 

“The proof that microorganisms from fruits and vegetables can colonize the human gut has now been established for the first time.”U Graz has already started another study to further this area of research.  

The analysis was narrowed down to two fundamental studies, the Teddy project, which looked at the development of babies in long-term research and the American Gut Project, which studied the intestinal microbiome of adults. Both projects collected data on the food intake of the test persons.

The researchers used metagenome data from around 2,500 samples containing between one and 10 million sequences. 

To further this research within the EU-funded Hedimed project, Berg has started working on an intervention study where people on three continents eat the same foods for a given period and are tested.

“Fresh fruit and vegetables will always have the best microbiome. Agriculture or processing companies already have a major influence here and the storage and processing of food must also be critically reconsidered,” explains Berg. 

“Depending on the findings of the planned study, there could also be exciting applications for individuals. “Every fruit and vegetable has a unique microbiome. So maybe at some point, a personalized diet can be put together based on that.”

This research is anchored in the human and biotechnology field, one of five strategic foci of TU Graz.

Meanwhile, the World Gastroenterology Organisation chose ‘A Healthy Gut from the Start’ for the World Digestive Health Day campaign, which focused on how gut health develops inside the womb and the changing dietary needs of the gastrointestinal tract from birth through to infancy, childhood and adulthood.  

By Inga de Jong