Vitamin B12 is essential for maintaining red blood cell size and as one of the B vitamins, essential for DNA synthesis as well. It also prevents degeneration of the spinal cord, optic nerves, cerebral tissue, and peripheral nerves. Vegetarians should be aware of the lack of B12 in their diet if it excludes eggs and dairy products.
Vitamin B12 status and rate of brain volume loss in community-dwelling elderly.
Those who have a vitamin B12 deficiency are more prone to heart palpitations, shortness of breath, pale skin, diarrhea, and nerve problems such as numbness or tingling.