The following information comes from the book
Depression: The Way Out
by Neil Nedley, M.D., available through this Web site.

Vitamin B-12 is vital to optimal health of the nervous system. Symptoms of a deficiency of this vitamin are poor coordination, frequent forgetfulness, and Depression. It can even affect the personality. Many patients with B-12 deficiency have been mistakenly diagnosed as having Alzheimer's disease. Information on Vitamin B-12 is as follows:

• Found in fortified plant food and animal products

• Vegans and meat eaters can have Vitamin B-12 deficiency

• Taking Vitamin B-12 supplements is advised

• The supplement should be thoroughly chewed

This essential vitamin is found most reliably in animal products and fortified plant foods. however, even a diet that is adequate in Vitamin B-12 does not ensure adequate blood levels of this vitamin. Vitamin B-12 has one of the most complicated absorption processes of any nutrient. It requires appropriate interaction in the mouth and stomach before it is successfully absorbed in the small intestine. As we age, it is common to lose some of the stomach's absorptive capacities. Consequently by the time we reach 80, if we rely on food alone to give us our Vitamin B-12, we have about a one-in-five chance of developing serious problems and deficiencies. Taking Vitamin B-12 supplements is advised, and they should be chewed rather than swallowed whole.

Although many associate Vitamin B-12 deficiency with a vegan or vegetarian diet, only a small percentage of people with Vitamin B-12 deficiency are vegetarian.