Beriberi or Wernicke-Korsakoff syndrome, which are characterized by neurologic and psychiatric symptoms, and are often seen in alcoholics or patients who have had weight loss surgery.
Riboflavin (vitamin B2)
Cheilosis, glossitis, seborrheic dermatitis (often affecting the genital areas), pharyngitis, and edema and/or erythma of the mouth.
Niacin (vitamin B3)
Pellagra (Diarrhea, Dermatitis, Dementia, Death)
Pyridoxine (vitamin B6)
Nonspecific stomatitis, glossitis, cheilosis, irritability, confusion, and depression.
Folate (vitamin B9)
Neural tube defects
Cyanocobalamin (vitamin B12) causes megaloblastic anemia and peripheral neuropathy.