Which disease can vitamin B deficiency cause?

Vitamin B is a group of nutrients, so the effect depends on which type is low. This question commonly refers to vitamin B12 deficiency. Vitamin B12 supports the production of healthy blood cells and helps maintain the nervous system. A shortage can lead to anaemia, with reduced oxygen delivery that may contribute to fatigue, dizziness or generalised weakness. Nerve involvement may cause tingling, numbness, balance changes or burning sensations in the hands and feet; these features fit peripheral neuropathy. Some people also notice memory problems or difficulty concentrating.

The deficiency may develop because the diet contains little vitamin B12, the stomach or bowel cannot absorb it properly, or a condition such as coeliac disease interferes with absorption. Symptoms can have other explanations, so the symptom alone does not establish the cause.

Arrange a medical assessment if symptoms persist, recur or are affecting daily activities. A clinician may ask about food intake, digestive symptoms, medicines and previous operations, then use blood tests to check blood-cell changes and vitamin levels. Further tests may be needed when absorption is suspected.

Treatment depends on the reason for the deficiency. It may involve an oral supplement or injections, along with addressing an absorption problem or dietary gap. Do not take high-dose supplements as a substitute for assessment: they can complicate interpretation of later tests and may not correct the underlying problem.

Seek prompt medical advice for new numbness, worsening weakness, unsteady walking, repeated falls, breathlessness with ordinary activity, chest discomfort or fainting. Get urgent help for sudden one-sided weakness, new trouble speaking, severe breathing difficulty or a sudden severe change in alertness. These warning signs need assessment because they can have causes unrelated to vitamin deficiency.

Ask which vitamin is low, whether the blood results show anaemia, and whether your symptoms suggest nerve involvement. You can also ask what may be affecting absorption, whether a supplement or injection is appropriate, how long treatment should continue, and which symptoms should trigger an earlier review.