Vitamin B12 deficiency is thought to affect up to 6% of the adult population and nearer 20% of people aged over 60. Causing anaemia and nerve damage, it is important to identify vitamin B12 deficiency before it causes lasting damage.
Vitamin B12 is vital for the formation of red blood cells; low levels can cause misshapen and enlarged red blood cells which compromise your body's ability to transport oxygen round the body.
The most common cause of vitamin B12 deficiency is an autoimmune condition called pernicious anaemia. Other causes include lack of dietary B12 (vegans and vegetarians are particularly at risk), people on certain medications such as metformin, and people with malabsorption problems.
B12 deficiency causes symptoms of fatigue, shortness of breath, a swollen tongue, brain "fog", brittle nails and nerve damage.