This is the information I have for you hope it helps:
Basically, vitamin B 12 is necessary for healthly blood. In the body it acts as co-enzyme for normal DNA synthesis. Therefore, it promotes normal fat and carbohydrate metabolism and protein syntheses. Because of this, it promotes growth and cell development and blood-cell development.
When your body has enough B 12 you have and increased resistance to infection and disease.
And to answer your question vitamin B 12 increases your appetitie and promotes growth. It will also increase your energy.
This is all due to the fact that it is an aid in metabolism.
Vitamin B 12 is found in various foods, including fish, egg yolks, milk, and fermented cheeses, but it also can be supplemented using 3 different methods: caplets, nasal gel or by injection.