 Vitamin B12 is not found in plant sources; a vegetarian diet can be a risk factor for vitamin B12 deficiency.Normal daily intake of vitamin B12 is 7–30 micro gram, cooking has minimal effect on the structure of this vitamin.The minimal daily adult requirement is 1–3 micro gram, and the human body is able to store at any one time about 2–3 milligram, which is sufficient for at least 2 years of impeccable functioning before the source is depleted.