Also known as the "caveman diet," the increasingly-popular paleo diet is claimed to be good for weight loss, gut health, blood pressure control, and other factors. According to new research, however, it may also boost the risk of heart disease.

Intended to replicate the more "natural" diet that people followed in the stone age, the paleo diet emphasizes the eating of meat, vegetables, nuts and some fruit, while it excludes grains, legumes, dairy, salt, refined sugar and processed oils.

In a recent study conducted at Australia's Edith Cowan University, scientists studied 44 adults who had been on the diet for at least a year, along with 47 others who were following a traditional Australian (Western-style) diet. Among other things, the researchers found that individuals from the paleo group had significantly higher levels of an organic compound known as trimethylamine-n-oxide (TMAO) in their bloodstream. TMAO is produced in the gut, and high levels of it have previously been linked to heart disease.

It is believed that the elevated TMAO levels are likely linked to higher concentrations of the bacteria that produces the compound, which were also found in the paleo dieters. The plentitude of those bacteria may in turn be due to the lack of whole grains in the diet.

"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," says lead scientist, Dr. Angela Genoni. "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."

It was additionally noted that the large amount of red meat included in the diet provides the compounds necessary for production of TMAO, plus it boosts the intake of potentially-harmful saturated fats to approximately twice the recommended level. Populations of beneficial bacteria, on the other hand, were lower in the paleo group, leading to an increased risk of other health problems.

A paper on the research was recently published in the European Journal of Nutrition.