Vitamin B12 is involved in helping the body make red blood cells, keeping the nervous system healthy, releasing energy from food. It also plays an essential role in red blood cell formation, cell metabolism, nerve function and the production of DNA.

A deficiency in vitamin B12 can cause a wide range of problems, including: extreme tiredness a lack of energy pins and needles (paraesthesia) a sore and red tongue mouth ulcers muscle weakness disturbed vision psychological problems, which may include depression and confusion problems with memory, understanding and judgement

Animal liver and kidneys, clams and sardines are rich in B12.