Vitamin B12

Vitamin B12 is important in the formation and functions of the blood and nerves. It is a critical factor in the metabolism of folate for DNA manufacture and is required during rapid cell growth.

Recommended daily intakes (RDI) for Vitamin B12 (µg/day)


Age (years)










Vitamin B12 deficiency

Deficiency is not usually caused by a lack of Vitamin B12 in the diet but by failure of an intrinsic factor in the body which assists in the absorption of Vitamin B12. Older people are more at risk of deficiency as absorption declines with age. Symptoms are commonly megaloblastic anaemia, (enlarged red blood cells) and, less commonly, neurological abnormalities.

Vegans are also at risk of deficiency because dietary Vitamin B12 is only found in meat or meat products. Vegans may need to consider supplementation, although this should be discussed with a medical professional.

Food sources of Vitamin B12

Vitamin B12 is produced almost entirely by bacterial synthesis in the colon and small intestine. Rich sources of Vitamin B12 are meat, seafood, milk, milk products and eggs.