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.
Calories, Protein & Fat. It is important for people trying a vegan diet to include some high-calorie, high-protein foods in order to feel satisfied. Simply removing animal products from a typical American diet is going to leave you with mostly low-calorie foods such as salads, vegetables, and fruit.