A study recently published in the European Journal of Nutrition found following a strict Paleo diet may be associated with gut changes that are bad for heart health. The study assessed the dietary intake of 44 self-reported followers of the Paleo diet (which excludes processed foods, grains, dairy, and legumes). It compared their measures of cardiovascular health to 47 controls consuming a generally healthy dietary pattern consistent with national dietary guidelines. The Paleo diet followers had higher levels of HDL (good) cholesterol, but strict followers also had significantly higher blood levels of TMAO, a compound that has been associated with higher risk of cardiovascular disease. TMAO levels were associated with higher intake of red meat and lower intake of total and whole grains. Stool analysis suggested that the Paleo diet changed gut microbiota to favor those organisms involved in the formation of TMAO. Consuming higher amounts of whole grains, prohibited in Paleo diets, was associated with lower TMAO levels.