As you read along, you'll find out that most health conditions developed by vegans are related to vitamin B12 deficiency. Without the familiar sources of vitamin B12, certain bodily functions can be disrupted, leading to anemia, gastritis, stroke, Crohn's disease, and Celiac disease.

Vegetarians and vegans often avoid eating animal products for similar reasons. The largest difference is the degree to which they consider animal products acceptable. For instance, both vegans and vegetarians may exclude meat from their diets for health or environmental reasons.

Some studies have shown that those on a plant-based diet are found to have lower plasma vitamin B12 levels and higher levels of vitamin B12 deficiency than those who consume animal products. Vitamin B12 is an important cofactor in DNA synthesis, and deficiency can lead to anemia and severe neurological dysfunction.

Vegan diets have also been shown to help in the treatment of type 2 diabetes by lowering total and LDL cholesterol and by controlling lipid levels, for example by reducing triglycerides, a type of fat that is also associated with a greater risk of heart disease (Jenkins et al.