Vitamin B12 is a water-soluble vitamin also known as cyanocobalamin. It is very important in new cell synthesis, maintenance of nerve forms and works closely with folate to convert to its active form, folic acid.
Why you may need vitamin B12
Pernicious anemia is a type of anemia caused by lack of ‘intrinsic factor’. This is a glycoprotein secreted by your stomach that is essential for intestinal absorption of vitamin B12. It attaches itself to vitamin B12 and is then transported to the ileum (section of the small intestine), where it is slowly absorbed. Intrinsic factor may be decreased by any surgical removal of parts of the stomach, age (>65years), increased or decreased gastric pH or use of antacid drugs.
Vitamin B12 is usually given intramuscularly in cases where very little is being absorbed by the digestive system
Diabetic neuropathy, Alzheimer’s disease, mouth ulcers, HIV, herpes zoster (shingles) and high homocysteine – low levels of vitamin B12 have been noted in people with these conditions.
Neural tube defects – vitamin B12 converts folate to its active form. Lack of vitamin B12 can trap folate.
How much do you need?
Recommended Daily Intake (RDI)
Adults (over 19 years): 2.4mcg daily
Pregnancy: 2.6mcg daily
Breastfeeding: 2.8 mcg daily
Children 9-13 years: 1.8mcg daily
Children under 14-18 years: 2.4mcg daily
Symptoms of deficiency
Your body stores a large quantity of vitamin B12 and if you become deficient it can take months to years for symptoms to appear. Deficiency of vitamin B12 leads mainly to haematological type symptoms and due to demyelination of nerves – neurological symptoms.
Symptoms include megaloblastic anaemia, weakness, tingling, numbness, inflamed sore tongue, digestive disturbances, delayed growth, elevated homocysteine, depression, memory loss, poor concentration and personality changes.
The best dietary sources of vitamin B12 include liver, brain, seafood, red meat and milk.
Other reasons why you may need more
Considering that the best dietary sources are from animal products, it is very common for vegetarians to be vitamin B12 deficient. In addition your demand may be increased during pregnancy, stress, in hyperthyroidism, parasitic or bacterial infections, liver disease, cigarette smoking and excessive alcohol intake.
- Vitamin B12 is generally well tolerated but in some people can cause diarrhoea, itching and polycythemia vera, which is an increase in blood volume and the number of red blood cells.
- Large doses of folic acid (>1000mcg) can mask a vitamin B12 deficiency. If you are vitamin B12 deficient, folic acid will improve vitamin B12 associated anaemia, but it will allow the neurologic abnormalities and potentially irreversible neurological damage to progress.
- Before taking high doses of folic acid, you should check with your healthcare professional about testing vitamin B12 status.