Parkinson's disease (PD) is a type of movement disorder. It happens when nerve cells in the brain don't produce enough of a brain chemical called dopamine. Sometimes it is genetic, but most cases do not seem to run in families. Exposure to chemicals in the environment might play a role.
Why Vegans are Often Deficient in Vitamin B12. The few plant foods that are sources of B12 are actually B12 analogs. An analog is a substance that blocks the uptake of true B12, so your body's need for the nutrient actually increases.
The vegan or total vegetarian diet includes only foods from plants: fruits, vegetables, legumes (dried beans and peas), grains, seeds and nuts. The lactovegetarian diet includes plant foods plus cheese and other dairy products. The ovo-lactovegetarian (or lacto-ovovegetarian) diet also includes eggs.