People who follow a vegan lifestyle strict vegetarians who try to eat no meat or animal products of any kind may increase their risk of developing blood clots and atherosclerosis or "hardening of the arteries," which are conditions that can lead to heart attacks and stroke. That's the conclusion of a review of dozens of articles published on the biochemistry of vegetarianism during the past 30 years. The article appears in ACS' bi-weekly Journal of Agricultural and Food Chemistry.
Duo Li notes in the review that meat eaters are known for having a significantly higher combination of cardiovascular risk factors than vegetarians. Lower-risk vegans, however, may not be immune. Their diets tend to be lacking several key nutrients including iron, zinc, vitamin B12, and omega-3 fatty acids. While a balanced vegetarian diet can provide enough protein, this isn't always the case when it comes to fat and fatty acids. As a result, vegans tend to have elevated blood levels of homocysteine and decreased levels of HDL, the "good" form of cholesterol. Both are risk factors for heart disease.
It concludes that there is a strong scientific basis for vegetarians and vegans to increase their dietary omega-3 fatty acids and vitamin B12 to help contend with those risks. Good sources of omega-3s include salmon and other oily fish, walnuts and certain other nuts. Good sources of vitamin B12 include seafood, eggs, and fortified milk. Dietary supplements also can supply these nutrients.
"Chemistry behind Vegetarianism", Journal of Agricultural and Food Chemistry.