Overview
Vitamin B12 deficiency occurs when the body lacks enough B12, a vitamin needed for healthy nerves, brain function, and red blood cell production. It can develop from not eating enough B12 or from the body not absorbing it properly. If left untreated for a long time, it can cause nerve damage that may not fully reverse.
Symptoms
- Tiredness and weakness
- Tingling or numbness in hands and feet
- Trouble with balance or walking
- Memory problems or difficulty concentrating
- Sore, red, or smooth tongue
- Pale or slightly yellow skin
- Mood changes or irritability
Causes & risk factors
- Vegan or strict vegetarian diet without supplements
- Pernicious anemia, an autoimmune condition affecting absorption
- Stomach or bowel surgery
- Long-standing digestive conditions such as Crohn's disease
- Older age, which reduces absorption
- Certain long-term medications that affect stomach acid
Treatment & self-care
Care involves blood tests to confirm the deficiency and identify whether it is a dietary or absorption problem. Treatment generally involves replacing B12 through diet, oral supplements, or injections depending on the cause, since some people cannot absorb it from food. A licensed clinician should diagnose the cause, choose the route of treatment, and monitor recovery, especially if nerve symptoms are present.
See a doctor urgently if
- You have numbness, tingling, or balance problems
- You notice memory or thinking changes
- You follow a vegan diet and feel persistently tired
- You have a digestive condition or have had gut surgery
- Symptoms continue despite dietary changes