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 true vegetarian eats no meat at all, including chicken and fish. A lacto-ovo vegetarian eats dairy products and eggs, but excludes meat, fish, and poultry. It follows, then, that a lacto vegetarian eats dairy products but not eggs, whereas an ovo vegetarian eats eggs but not dairy products. A stricter form of vegetarianism is veganism (pronounced: VEE-gun-izm). Not only are eggs and dairy products excluded from a vegan diet, so are animal products like honey and gelatin.