Meatless eating typically improves cardiovascular health, but new research suggests that a dietary shortage of a crucial vitamin leads to an overabundance of the amino acid homocysteine in some vegetarians, which could pose a risk to their hearts.
A high homocysteine concentration in blood is associated with an elevated risk of heart disease. In past studies, people who have a homocysteine concentration of 15 micromoles per liter (mol/l) in their blood while fasting have a 60 to 80 percent greater risk of cardiovascular disease than do study volunteers with 10 mol/l, a more typical concentration.
Metabolic processes continually derive homocysteine by converting another amino acid, methionine, and also reconvert homocysteine into methionine. The latter reaction requires several essential nutrients, including vitamins B6 and B12. Deficiencies of these vitamins, therefore, can result in a buildup of homocysteine.