Vitamin B12

Introduction

Vitamin B12 is a member of the vitamin B complex. It contains cobalt therefore is also known as cobalamin. It is exclusively synthesized by bacteria and is found in meat, eggs and dairy products. There has been considerable research into proposed plant sources of vitamin B12. Fermented soya products, seaweeds, and algae such as spirulina have all been suggested as containing significant B12. However, the present consensus is that any B12 present in plant foods is likely to be unavailable to humans and so these foods should not be relied upon as safe sources. Many vegan foods are supplemented with B12.

Functions of vitamin B12

Vitamin B12's primary functions are as follows:

1. Formation of red blood cells and the maintenance of a healthy nervous system.
2. B12 is necessary for the rapid synthesis of DNA during cell division.
3. B12 is also important in maintaining the nervous system.
4. B12 plays a vital role in the metabolism of fatty acids essential for the maintenance of myelin.
5. Vitamin B12 can be stored in small amounts by the body.

Symptoms

The symptoms are excessive tiredness, breathlessness, listlessness, pallor, and poor resistance to infection. Other symptoms can include a smooth, sore tongue and menstrual disorders. Anaemia may also be due to folic acid deficiency, folic acid also being necessary for DNA synthesis.

Dietary Sources

The only reliable unfortified sources of vitamin B12 are meat, dairy products and eggs. There has been considerable research into possible plant food sources of B12. Fermented soya products, seaweeds and algae have all been proposed as possible sources of B12.The current nutritional consensus is that no plant foods can be relied on as a safe source of vitamin B12.

Good sources of vitamin B12 for vegetarians are dairy products or free-range eggs. ½ pint of milk (full fat or semi skimmed) contains 1.2 µg. A slice of vegetarian cheddar cheese (40g) contains 0.5 µg. A boiled egg contains 0.7 µg. Fermentation in the manufacture of yoghurt destroys much of the B12 present. Boiling milk can also destroy much of the B12.

Vegans are recommended to ensure their diet includes foods fortified with vitamin B12. A range of B12 fortified foods are available. These include yeast extracts, vegetable stock, veggie burger mixes, textured vegetable protein, soya milks, vegetable and sunflower margarines, and breakfast cereals.

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