Serum levels of the cardiovascular disease biomarker trimethylamine N-oxide (TMAO) are doubled in people who follow a Paleolithic diet, the world's first major study examining the effect of the diet on gut bacteria has found.
The cross-sectional study, published in the European Journal of Nutrition, examined the association between dietary intake, markers of colonic health, microbiota and serum TMAO.
The paleo diet advocates eating meat, vegetables, nuts and limited fruit, and excludes grains, legumes, dairy, salt, refined sugar and processed oils. The researchers compared 44 people who had been on the paleo diet for over a year (either strictly or partially adherent), with 47 people following a traditional diet.
Long-term consumption of a paleo diet was associated with markedly higher serum TMAO concentrations, but only in those who adhered to the diet strictly.
Lead researcher Dr Angela Genoni said the reason TMAO was so elevated in people on the paleo diet appeared to be the lack of whole grains in their diet.
"We also found that populations of beneficial bacterial species were lower in the Paleolithic groups, associated with the reduced carbohydrate intake, which may have consequences for other chronic diseases over the long term," she said.