One study interviewing members of the Pernicious Anaemia Society found that nearly half of the patients had been misdiagnosed.
A further 20 per cent had waited two years or more for a proper diagnosis.
Low levels of vitamin B12 could also lead to nerve damage, as the vitamin is essential to producing myelin, which protects nerve cells from damage.
Symptoms of low B1 might initially feel like tingling or numbness in hands and feet, or difficulty with balance.
