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.
Five Common Vegetarian Nutrition Deficiencies. A vegetarian diet and its many forms, such as lacto and/or ovo-vegetarian, pescatarian or vegan, can easily meet all nutritional requirements, though there are certain considerations to monitor when eating a plant-based diet to ensure access to all essential vitamins, minerals and fatty acids.