Watch for these signs of Vitamin B12 Deficiency

Fatigue
Weakness
Weight loss

Constipation
Infertility
Vision problems
Loss of hearing and tinnitus

Alcoholism
Impotence
Incontinence
Hyperpigmentation and hypopigmentation
(dark and light patches in the skin)
Neuralgia, neuritis and bursitis
Anemia, including pernicious anemia
Spinal cord degeneration
Psoriasis and other skin problems
Brain degeneration
Insomnia
Any emotional disorder up to and including insanity

Poor growth/failure to thrive in infants
Inflamed tongue
Premature grey hair
Disturbed carbohydrate metabolism
Numbness and tingling in the hands and feet
Irrational or chronic anger
Violent behavior
Lack of balance/abnormal gait
Combat fatigue