Vitamin B6 is also called pyridoxine. It is involved in the process of making serotonin and norepinephrine, which are chemicals that transmit signals in the brain. Vitamin B6 is also involved in the formation of myelin, a protein layer that forms around nerve cells.
A deficiency of vitamin B6 can result in disruption in the normal functioning of the central nervous system. It can also lead to various problems of the tissues in and around the mouth. These problems can include cheilosis (cracking of skin around corners of mouth), glossitis (inflammation of tongue), stomatitis (sores in and around mouth), and cracked, painful lips.
Very large doses (over 200 milligrams a day) of vitamin B6 can result in nervous system disorders, including numbness in the legs and a loss of balance, if taken for extended periods of time. Vitamin B6 toxicity could cause damage to sense nerves, resulting in numbness in the extremities and limbs. Additional nervous system related symptons of an overdose of pyridoxine could include loss of coordination, trouble walking, decreased sensitive to touch and temperature, and fatigue.