People who follow a Paleo diet have twice the amount of a key blood biomarker that is closely linked to heart disease, the world's first major study examining the impact of the diet on gut bacteria has found.
For the study, researchers compared 44 people on a Paleo diet with 47 following a traditional Australian diet and measured the amount of trimethylamine-n-oxide (TMAO) in participants' blood.
High levels of TMAO, an organic compound produced in the gut, are associated with an increased risk of heart disease.
What is a Paleo diet?
Proponents of the Paleo diet hold the belief that we should only consume food that our paleolithic ancestors consumed. They believe that meat, fish, eggs, nuts, fruits and vegetables are natural for humans to eat, but that whole grains, processed foods and dairy products are not. The diet also places an emphasis on consuming a higher amount of meat.
As such the diet includes meat, vegetables, nuts and limited fruits, and excludes grains, beans and lentils, dairy products, salt, refined sugar and processed oils.
Impact on gut health
Many Paleo diet proponents claim the diet is beneficial to gut health, but this new 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.
The researchers 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.
The researchers also found higher concentrations of the bacteria that produces TMAO in the Paleo group.
Missing whole grains to blame
The reason TMAO was so elevated in people on the Paleo diet appeared to be the lack of whole grains in their diet.
The Paleo diet excludes all grains and we know that whole grains are an excellent source of resistant starch and many other fermentable fibres that feed beneficial gut microbes.
Because TMAO is produced in the gut, a lack of whole grains might change the populations of bacteria enough to enable higher production of the compound.
As well, the Paleo diet includes greater servings of red meat which contains choline, a compound that’s used to make TMAO.
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