A tingling or numbness in the hands, legs or feet can be a sign of vitamin B12 deficiency.
The sensation frequently starts in the feet and moves to the hands.
The feelings may also be linked to problems with walking or even difficulty balancing.
Known to doctors as neuropathy, the problem can affect people of all ages, although it is particularly common in those over 50.
Around one-in-twelve people over 50 experiences the condition.
Other causes of neuropathy include autoimmune processes and genetics — however, the most common cause is diabetes.
Other common signs of vitamin B12 deficiency include jaundice, feeling dizzy and lethargy.
The body uses vitamin B12 to make red blood cells and to keep the nervous system healthy.
The good news is that vitamin B12 is easy to correct either with supplementation or a change in diet.
Foods high in vitamin B12 include dairy foods, beef, salmon, eggs and low-fat milk.
Dr John D. England, a neurologist at Louisiana State University Health Sciences Center in New Orleans, said:
“People with suspected nerve problems should talk to their doctors about screening tests, especially blood glucose, vitamin B12 level and serum protein levels, since these tests can often point to common causes of neuropathy.”
People who may have difficulty getting enough vitamin B12 include vegetarians, older people and those with some digestive disorders, such as Crohn’s disease.
Dr England said:
“There are many people with a neuropathy who have been walking around for years without having been diagnosed and treated.
Both neurologists and people with neuropathy need to know that the appropriate choice of tests is critical to accurate diagnosis.”
The guidelines were published in the American Academy of Neurology.