RDI
Overdosing
Conception, pregnancy and breastfeeding
Food sources
Vitamin B12 (known as cobalamin) is a water-soluble vitamin closely related to folic acid. Each relies on the other for the body to be able to use them. Vitamin B12 is essential for the efficient metabolism of protein, carbohydrates and fats in the body and contributes to the production of red blood cells to prevent anaemia. It also maintains the protective cover around the nerves and promotes their growth.
Vitamin B12 is excreted though the liver and passed into the bowel. Here it is reabsorbed by the body through the intestines. Vitamin B12 deficiency usually only occurs if a person's bowel has a disorder that prevents them from reabsorbing Vitamin B12, (rather than their diet being insufficient), a condition called pernicious anaemia. However, because Vitamin B12 is only available in meat and dairy products and not plant foods vegans may also be at risk of vitamin B12 deficiency. Vitamin B12 absorption is also inhibited by the drug metformin (taken for type 2 diabetes and insulin resistance), making B12 levels unusually low. This is treated with B12 injections every three months.
Vitamin B12 deficiency (although very rare) can lead to anaemia, an inflamed tongue and mouth, fatigue and the degeneration of nerves, eventually leading to permanent paralysis. Babies born to mothers who are vitamin B12 deficient are at risk of spinal cord damage and possibly a severe inability to move well. If the mother is vitamin B12 deficient while breastfeeding, her baby can also exhibit limited movement. Your paediatrician may prescribe vitamin B12 supplements to help reverse the majority of these signs, but there can be permanent learning and language delays.