Translations:Vitamin B12/18/en

Deficiency

Main article: Vitamin B₁₂ deficiency

Vitamin B₁₂ deficiency can potentially cause severe and irreversible damage, especially to the brain and nervous system. Deficiency at levels only slightly lower than normal can cause a range of symptoms such as fatigue, feeling weak, lightheadedness, dizziness, breathlessness, headaches, mouth ulcers, upset stomach, decreased appetite, difficulty walking (staggering balance problems), muscle weakness, depression, poor memory, poor reflexes, confusion, and pale skin, feeling abnormal sensations, among others, especially in people over age 60. Vitamin B₁₂ deficiency can also cause symptoms of mania and psychosis.