According to a study published in the Journal of Agriculture and Food Chemistry, the vegan lifestyle may increase people's risk of blood clots and the hardening of arteries - conditions which can lead to heart attacks and strokes.

The study out of Hangzhou, China, was based on a review of dozens of articles on the biochemistry of vegetarianism published over the last 30 years. While meat eaters have significantly higher cardiovascular risk factors than vegetarians, the study noted that vegans tend to have elevated blood levels of homocysteine, an amino acid related to a higher risk of coronary heart disease, and decreased levels of HDL, also known as "good" cholesterol.