Food-borne ill­nesses, such as those due to a cer­tain strain of Escherichia coli (E. coli), cause debil­i­tat­ing and poten­tially deadly infec­tions through­out the world every year.

A recent study found a plant-based diet reduced the risk of the mal­adies in mice. While it is too soon to apply the results to humans, the inves­ti­ga­tion adds to the body of evi­dence that sug­gests eat­ing a diet rich in fruits, veg­eta­bles and whole grains is ben­e­fi­cial for health.

The strain of E. coli, called EHEC, is cur­rently under inves­ti­ga­tion in regard to a gas­troin­testi­nal infec­tion out­break asso­ci­ated with romaine let­tuce, reported authors of the research at the University of Texas Southwestern Medical Center. EHEC causes dan­ger­ous inflam­ma­tion in the colon that man­i­fests in vom­it­ing and bloody diar­rhea.

“There has been a lot of hearsay about whether a plant-based diet is bet­ter for intesti­nal health than a typ­i­cal Western diet, which is higher in oils and pro­tein but rel­a­tively low in fruits and veg­eta­bles,” researcher Vanessa Sperandio, pro­fes­sor of micro­bi­ol­ogy and bio­chem­istry, said in a press release. ​“So we decided to test it.”

“Plant-rich diets are high in pectin, a gel-like sub­stance found in many fruits and veg­eta­bles,” she added. ​“Pectin is digested by the gut micro­biota into galac­tur­onic acid, which we find can inhibit the vir­u­lence of EHEC.”

Sperandio explained that intesti­nal pathogens such as EHEC try to estab­lish a foothold among the ben­e­fi­cial bac­te­ria that reside there. The com­mu­nity of microbes in the gut includes harm­less vari­eties of E. coli as well as other strains, many of which aid diges­tion and serve as a bar­rier to infec­tion-caus­ing bac­te­ria. EHEC breaks through the bar­rier by secret­ing T3SS, a sub­stance that trig­gers inflam­ma­tion and pro­duces symp­toms of the infec­tion.

According to Sperandio, the study dis­cov­ered that the ben­e­fi­cial E. coli strains use dif­fer­ent sug­ars for food than the path­o­genic ones such as EHEC. Moreover, another strain of ben­e­fi­cial gut bac­te­ria breaks down the pectin in fruits and veg­eta­bles to form the sugar galac­tur­onic acid.

Once this acid gets low, EHEC and other gut pathogens increase the secre­tion of T3SS, thus becom­ing more vir­u­lent. Because reg­u­larly eat­ing foods con­tain­ing pectin helps main­tain lev­els of galac­tur­onic acid, the gel-like sub­stance sup­presses the increased vir­u­lence.

The researchers observed that pectin’s effects led to improved resis­tance to EHEC. Compared to mice fed reg­u­lar food, those on the pectin-enriched food had a much lower inci­dence of becom­ing ill from the pathogen. In addi­tion, mice on the diet with pectin had 10,000 bac­te­ria in the cecum, while those on the reg­u­lar diet had one mil­lion bac­te­ria in this area, Sperandio noted.

However, fur­ther research is needed before it is proven that eat­ing more fruits and veg­eta­bles is likely to reduce the risk of a food-borne infec­tion like EHEC, Sperandio told Olive Oil Times.

“At this point, it would be jump­ing to con­clu­sions,” she said. ​“I’d rather be care­ful here, given the com­plex­ity of pathogen-host asso­ci­a­tions and the fact that our stud­ies are in mice. Therefore, it’s a bit early to trans­late these find­ings to the human diet.”

However, the authors did con­clude that dietary sugar avail­abil­ity, such as the galac­tur­onic acid cre­ated from pectin, can influ­ence the rela­tion­ship between the bac­te­r­ial com­mu­nity in the gut and intesti­nal pathogens, along with dis­ease out­comes.

The study was pub­lished in Nature Microbiology.

• Nature Microbiology


• University of Texas Southwestern Medical Center