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.
What Can Go Wrong with a Vegan Diet. In theory, vegans replace the animal products with lots of whole foods like fruits, veggies, nuts, beans and whole grains. The reality, however, can often be quite different. What do vegans eat, in most cases? Switching to a vegan diet doesnât mean people suddenly become immune to all the food temptations out there.