People on the paleo diet have two times the amount of a key blood biomarker that is clearly associated with heart disease, reveals a new study. The findings of the study are published in the European Journal of Nutrition.
Researchers from Edith Cowan University (ECU) compared 44 people on a diet with 47 following a traditional Australian diet.
The research measured the amount of trimethylamine-n-oxide (TMAO) in participants' blood.
Impact on gut health
The controversial Paleo (or 'caveman') diet advocates eating meat, vegetables, nuts, and limited fruit, and excludes grains, legumes, dairy, salt, refined sugar and processed oils.
Lead researcher Dr. Angela Genoni said that with the diet's growing popularity, it was important to understand the impact it could have on overall health.
"Many Paleo diet proponents claim the diet is beneficial to gut health, but this research suggests that when it comes to the production of TMAO in the gut, the Paleo diet could be having an adverse impact in terms of heart health," she said.
"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."
Reduced intake of whole grains to blame
She 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 found the lack of whole grains were associated with TMAO levels, which may provide a link between the reduced risks of cardiovascular disease we see in populations with high intakes of whole grains," she said.
The researchers also found higher concentrations of the bacteria that produce TMAO in the Paleo group.
"The Paleo diet excludes all grains, and we know that whole grains are a fantastic source of resistant starch and many other fermentable fibers that are vital to the health of your gut microbiome," Dr. Genoni said.
"Because TMAO is produced in the gut, a lack of whole grains might change the populations of bacteria enough to enable higher production of this compound.
"Additionally, the Paleo diet includes greater servings per day of red meat, which provides the precursor compounds to produce TMAO, and Paleo followers consumed twice the recommended level of saturated fats, which is cause for concern.
Dr. Angela Genoni initially presented her findings at the Nutrition Society of Australia Conference last year. This is the first time the findings have been published in a peer-reviewed journal.