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Paleo diet can be harmful for cardiovascular health

New research has found that there are high levels of a blood biomarker related to heart disease in people who follow the Paleolithic, or Paleo diet. The result raises some red flags about this type of diet, which is not safe enough to ensure good health, the researchers suggest.

A new study finds that a Paleo diet could endanger heart health.
A new study finds that a Paleo diet could endanger heart health.

For short, the Paleolithic diet— also known as the Paleo diet— attempts to mimic what modern-day human ancestors used to consume.

People who follow a Paleo diet have a high intake of meat, fruit, vegetables, nuts and seeds but no dairy, legumes or whole grains.

This type of diet was surrounded by controversy and researchers debated whether it is safe and healthy or not.

For example, one 2016 study suggests that the Paleo diet could protect against heart attacks and cardiovascular disease by increasing a protective molecule’s blood levels.

Yet another same year study made an entirely opposite discovery, concluding that this type of diet resulted in unhealthy weight gain and increased the risk of diabetes and cardiovascular problems.

Now, research conducted by an Australian team is pointing to more evidence suggesting that people following Paleo diets may put their heart health at risk.

The investigators hail from four different research institutions in Australia: the School of Medical and Health Sciences and the School of Science, both at Edith Cowan University, in Joondalup; the School of Molecular and Life Sciences, at Curtin University, in Bentley; PathWest Laboratory Medicine, in Nedlands; and CSIRO Health and Biosecurity, in Adelaide. The researchers’ findings appear in the European Journal of Nutrition.

High levels of biomarkers of heart disease

Researchers — led by Angela Genoni, Ph.D. — worked with 44 participants following Paleo diets, as well as 47 participants following typical diets that met national dietary advice.

The follow-up period was over a year, during which the researchers collected all participants ‘ biological samples, evaluated their diets, and compared results between the Paleo cohort and the control group.

In addition, to be more accurate in their evaluation, the authors divided the participants who adopted a Paleo diet into two different classes, according to their particular preferences:

  • strict Paleolithic (22 participants), including those who consumed less than one serving of grain per day and
  • pseudo Paleolithic dairy (22 participants), including those who consumed more than one serving.

The researchers found that individuals around Paleo communities displayed increased blood levels of a substance that is associated with heart disease by specialists: N-oxide trimethylamine.

Trimethylamine N-oxide first forms in the intestine, and its levels depend, among other things, on a person’s diet and the bacteria that inhabit their gut.

“Many Paleo diet proponents claim the diet is beneficial to gut health, but this research suggests that, when it comes to the production of [trimethylamine N-oxide] in the gut, the Paleo diet could be having an adverse impact in terms of heart health.”

Angela Genoni, Ph.D.

“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 adds.

Why Paleo may increase health risks

Genoni and the team suggests that people following Paleo diets have such elevated trimethylamine N-oxide levels because they don’t eat whole grains. These are a great source of dietary fiber, and help to reduce the risk of cardiovascular problems in a person.

“We found the lack of whole grains [was] associated with [trimethylamine N-oxide] levels, which may provide a link [with] the reduced risks of cardiovascular disease we see in populations with high intakes of whole grains,” says Genoni.

“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,” the lead researcher continues.

Moreover, the investigators point out that participants in the Paleo diet groups also had higher concentrations of the gut bacteria — Hungatella — that generate the compound.

“Since[ trimethylamine N-oxide] is produced in the gut, a lack of whole grains may change the bacteria populations enough to allow this compound to be produced higher,” Genoni explains.

“In addition, the Paleo diet includes higher portions of red meat per day, which provides the precursor compounds for producing[ trimethylamine N-oxide],” she notes, “and Paleo followers consumed twice the recommended level of saturated fat which is of concern.”

In conclusion to their study paper, the researchers warned that excluding whole grains from the diet could have a serious effect on the gut. We also argue that further studies are needed on the role of vegetables and saturated fats in regulating key biological mechanisms in the intestines.

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