Vitamin B12 is present in animal products such as eggs, dry beans, yeast, red meat, citrus fruits, green leafy vegetables and milk. Thus being on a diet and being a vegan would strongly create a big impact on one’s intake of these therefore making them more prone to this deficiency. Another cause of this deficiency is the aging process, because as one gets older, he or she tends to absorb less quantity of vitamin B12. Thus, this would deny ones capability of the body to be stimulated for it...