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.
A vegan does not eat meat, poultry, fish, eggs or dairy products. A lacto-vegetarian diet does not include meat, poultry, fish or eggs. However, lacto-vegetarians will eat dairy products, such as milk, cheese and yogurt. A lacto-ovo vegetarian diet only excludes meat, fish and poultry, while eggs and dairy products are allowed.