I has recently decided to go vegan. Do you follow any special diet?
No , vegetarianism had its origin from ancient India and ancient Greece.
There are a few versions of it. It is usually referred to abstaining from all animal products in the diet, and also big industrial farming of aniamls.
The diet was closely connected with the idea of nonviolence toward animals (called "ahimsa" in India),done as a religious practice
Donald Watson coined the tern in 1944 when he co founded the Vegan Society in England.  They defined it as the doctrine that man should live without exploiting animals.
Vegetarianism is strongly linked with a number of religions that originated in ancient India.such as buddhism, Hinduism.The killing of animals was sacred 
If you are strictly vegan, you need to take supplemental vitamins, like vitamin B12. 
Yeah,B12 is a food supplement,  Nutritional neuroscience is the scientific discipline that studies the effects various components of the balanced diet 
The liver of humans don't absorb vitamin a from animal meat very well, so it puts a strain on its functions.
Vitamin D
Vitamin D is a group of fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, and multiple other biological effects. In humans, the most important compounds in this group are vitamin D (also known as cholecalciferol) and vitamin D (ergocalciferol). Cholecalciferol and ergocalciferol can be ingested from the diet and from supplements. Only a few foods, such as the flesh of fatty fish, contain significant amounts of vitamin D.
The major natural source of the vitamin is synthesis
vegetarian diet that includes eggs and dairy.
- Vegan diet: In addition to the abstentions of a vegetarian diet, vegans do not use any product produced by animals, such as eggs, dairy products, or honey. The vegan philosophy and lifestyle is broader than just the diet and also includes abstaining from using any products tested on animals and often campaigning for animal rights.
Vegetarian diets Semi-vegetarian diets.
- Semi-vegetarianism: A predominantly vegetarian diet, in which meat is occasionally consumed.
- Kangatarian