Those who follow a Mediterranean diet have higher levels of health-promoting short-chain fatty acids in their gut, new research finds.
Adding to the considerable volume of research that shows that eating a diet high in fiber is good for you, the new study shows a direct link between the amount of fiber-rich foods consumed and the production in the gut of important, health-promoting short-chain fatty acids (SCFAs).
The research authors conclude by saying why a Mediterranean diet is particularly good.
SCFAs are produced when fiber from dietary plant matter is fermented in the colon. SCFAs include acetate, propionate and butyrate. Butyrate, for example, is the primary energy source for colonic cells, making it vital to colon health. It has anticarcinogenic and anti-inflammatory properties.
The Mediterranean diet is high in fiber-rich fruits, vegetables and legumes, compared with an Anglo-Saxon diet that includes a lot of red meat and dairy products.
For their study, the researchers analyzed the diets of 153 adults from around Italy. Over a single week they noted everything the participants ate. They also analyzed stool and urine samples - a way of assessing participants' gut bacteria and the "chemical fingerprints" of metabolites.
Of the 153 people taking part, 51 of them were omnivores, 51 were vegetarians and 51 were vegans. A Mediterranean diet made up 88% of what vegans ate, 65% of what vegetarians ate and 30% of what omnivores ate.
Microbial activity differed by diet
The researchers found that there were distinct patterns of microbial activity based on the eating patterns people had.
For example, it was found that those who ate a predominantly plant-based diet, particularly those who were vegan, had higher levels of Bacteroidetes in their gut, while those who ate a predominantly animal-based diet had higher levels of Firmicutes. Differing microbial species in these categories of organism - known as phyla - are better able to break down complex carbohydrates resulting in the all-important production of SCFAs.
Higher levels of SCFAs were found among vegans and vegetarians, as well as those who consistently consumed a Mediterranean diet.
It turns out that the quantity of fruit, vegetables, legumes and fiber consumed matters far more to the production of SCFAs than the type of dietary regime followed.
However, you can eat meat and benefit from the effects of SCFAs; the levels of a compound linked to cardiovascular disease - trimethylamine oxide (TMAO) - was far higher in the meat eaters than in the vegetarians and vegans. Sources of trimethylamine that the liver converts into TMAO include eggs, beef, pork and fish.
Commenting on their findings, the researchers say:
"We provide here tangible evidence of the impact of a healthy diet and a Mediterranean dietary pattern on gut microbiota and on the beneficial regulation of microbial metabolism toward health maintenance in the host."
It appears that being a vegan most of the time, a vegetarian some of the time and an occasional meat eater would produce one of the healthiest diets - namely the Mediterranean diet.
Earlier this month, Medical News Today reported on a study that found a Mediterranean diet supplemented with olive oil may reduce the risk of breast cancer.