Dietary Flavonoids May Help in Managing CF Through Impact on Gut Bacteria, Small Study Suggests

Consuming dietary flavonoids — compounds naturally found in fruits, vegetables, chocolate, and beverages like wine and tea — may be associated with changes in gut bacteria that potentially affect the body’s metabolism, immune function, and inflammation in patients with cystic fibrosis (CF), a small study reports.

The flavonoid-related changes in the gut microbiota may influence the management of lung disease and comorbidity (other disorders) in CF patients, its researchers said, particularly stressing the need to investigate the role of black tea, rich in specific flavonoids, in CF nutrition therapy.

The study “Associations between Flavonoid Intakes and Gut Microbiota in a Group of Adults with Cystic Fibrosis” was published in the journal Nutrients.

Gut microbiota, the community of microorganisms (bacteria, fungi, and viruses) that colonize the digestive tract, influences many aspects of human health, including metabolism and immune system response. Changes in gut microbiota have been implicated in several inflammatory conditions.

A few preliminary studies have shown that oral probiotics (live bacteria and yeast beneficial for gut health) may help reduce the frequency of pulmonary exacerbations, as well as gut inflammation and discomfort in children and adults with CF.

The disease is marked by chronic inflammation, metabolic malfunctioning like CF-related diabetes, and an increased risk of colorectal cancer, conditions that some suggest might be alleviated by a higher intake of flavonoids. The potential health benefits of flavonoids are thought to be linked to how they influence the gut’s microorganism composition.

Researchers in Australia investigated whether consuming flavonoids could contribute to the management of CF and its comorbidities via modulation of the gut microbiota.

In total, 18 adults with stable CF residing in Brisbane and Sydney were recruited. These patients reported on their diets and flavonoid-specific consumption using food diaries and surveys. Gut microbiota was determined by DNA sequencing in stool samples from the patients.

Results showed that among the several flavonoids tested, the intake of gallocatechin, a major black tea flavonoid, was especially associated with variations in the presence or absence of certain groups of bacteria.

A higher gallocatechin intake tended to correlate with more bacteria from the Actinomyces and Actinomycetaceae groups, and less with those from the Coriobacteriia class. Although the role of these bacteria in CF remains unknown, growing evidence suggests that they play roles in macronutrient metabolism, energy homeostasis, infection, and acute immune response.

Coriobacteriaceae bacteria in particular, which is predominant within Coriobacteriia, have been linked to colorectal cancer, to which CF patients are particularly susceptible.

“Assuming Actinomyces and Coriobacteriaceae influence the status of CF lung disease and colorectal cancer (CRC), and black tea and its flavonoids can indeed modify the gut microbiota in CF, modified nutritional therapies/recommendations incorporating this could have therapeutic potential to complement current management and/or reduce risk of lung disease and CRC in CF,” the researchers wrote.

Consumption of other flavonoids, namely apigenin and kaempferol (both found in many vegetables and fruits), were also associated with overall gut microbiome variations.

Overall, the team suggested that flavonoid intake seemed to influence the relative abundance of bacteria groups, and these changes might be relevant to managing inflammation-mediated CF comorbidities. 

“Understanding of the gut microbiota modulatory effect of dietary constituents such as flavonoids may help develop more holistic nutritional therapies targeting multiple CF-related conditions to further improve the quality of life in CF,” the researchers wrote. 

They also emphasized these results “stress the need to further investigate the role of black tea consumption in CF nutrition therapy, in view of black tea being a major dietary flavonoid source in a western diet.”