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.
Even though there are numerous benefits, there are also some important nutrition issues vegans should be aware of in order to thrive. 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.