Mediterranean Diet Boosts Beneficial Gut Bacteria

In recent years, a hot area of research is the gut micro­biome, as sci­en­tists are find­ing it has effects on health that go far beyond diges­tion. A new inves­ti­ga­tion dis­cov­ered the Mediterranean diet (MedDiet) may boost the diver­sity of bac­te­ria, as well as raise num­bers of the ben­e­fi­cial strains of bac­te­ria in the intesti­nal tract.

Using pri­mates, researchers designed the study to show what would hap­pen if the Western diet and MedDiet were con­sumed over a sus­tained period of time. A prob­lem involved in long-term stud­ies on humans is that they are usu­ally based on self-reported food ques­tion­naires, which results in an esti­ma­tion rather than a pre­cise cal­cu­la­tion of nutri­ent intake, lead author Hariom Yadav, assis­tant pro­fes­sor of mol­e­c­u­lar med­i­cine and micro­bi­ol­ogy and immunol­ogy at Wake Forest Baptist Medical Center, explained in a news release.

“We have about 2 bil­lion good and bad bac­te­ria liv­ing in our gut. If the bac­te­ria are of a cer­tain type and not prop­erly bal­anced, our health can suf­fer. Our study showed that the good bac­te­ria, pri­mar­ily Lactobacillus, most of which are pro­bi­otic, were sig­nif­i­cantly increased in the Mediterranean diet group,” Yadav added.

In the inves­ti­ga­tion, the pri­mates were ran­dom­ized to receive either the Western diet or the MedDiet for 30 months. As the Western diet eaten by humans includes plenty of red meat and sweets, the study’s ver­sion of it con­sisted of beef tal­low, lard, cho­les­terol, but­ter, eggs, sucrose and high-fruc­tose corn syrup.

Since the MedDiet is rich in fruits, veg­eta­bles, beans, oily fish, whole grains and olive oil; the study’s sim­u­la­tion of it involved fruit puree, veg­etable juice, olive oil, fish meal, fish oil, black and gar­banzo bean flour, but­ter, wheat flour, eggs and sucrose. The two diets had an equal num­ber of calo­ries.

At the end of the 30 months, fecal sam­ples were tested to ana­lyze the gut micro­biome, which is the com­mu­nity of ben­e­fi­cial and harm­ful bac­te­r­ial strains that reside in the intesti­nal tract.

The find­ings showed the bac­te­r­ial diver­sity of the gut was notice­ably higher in pri­mates on the MedDiet than those on the Western diet. Moreover, the ben­e­fi­cial bac­te­ria increased 7 per­cent in the for­mer but rose only 0.5 per­cent in the lat­ter.

In an inter­view with Olive Oil Times, Yadav spec­u­lated on what char­ac­ter­is­tics and prop­er­ties of the MedDiet may be respon­si­ble for its value to the micro­biome.

“it’s not known yet why and how the MedDiet can increase ben­e­fi­cial bac­te­ria in the gut; how­ever, we assume there might be two rea­sons. One is that the diet is rich in health­ful plant- and fish-based fat, which may serve as food to grow ben­e­fi­cial bac­te­ria. The other rea­son is that the MedDiet also has a high con­tent of plant-based fibers that can bet­ter feed the growth of good bac­te­ria like lac­to­bacilli,” he said.

When asked whether the MedDiet’s pos­i­tive effect on the gut micro­biome might be the one of the fac­tors respon­si­ble the eat­ing plan’s link to the lower risk of chronic dis­ease, Yadav replied that it may, indeed. They are inves­ti­gat­ing the pos­si­ble con­nec­tion fur­ther.

“Our pub­lished data have not shown any rela­tion­ship with chronic dis­eases; how­ever, our ongo­ing stud­ies are inves­ti­gat­ing the link of increased good bac­te­ria upon con­sump­tion of the MedDiet with improved meta­bolic and cog­ni­tive func­tions,” Yadav said.

The study was pub­lished in the jour­nal Frontiers in Nutrition.

• Frontiers in Nutrition


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