Signs of Vitamin B12 Deficiency Common Symptoms: Anemia Low red blood cells = poor oxygen flow. Tingling Hands & Feet A sign your nerves are struggling. Vitamin B12 Side Effects Unexpected Skin Changes? Could It Be B Deficiency? A patient presented with unexplained skin hyperpigmentation as the primary symptom. Surprisingly, the underlying cause turned out to be vitamin B deficiency. This case Medinaz Vitamin B12 Deficiency: Vitamin B12 deficiency is a nutritional or absorption related disorder leading to impaired DNA synthesis and neurologic dysfunction, commonly presenting with megaloblastic anemia and neuropsychiatric symptoms