Vitamin B12. What's the deal?
B12 is part of the B-complex group of vitamins, a group of 7 water-soluble vitamins that often get lumped together as the one thing (the ‘B vitamins’). Yet despite this, B12 is one of the vitamins that's often singled out for discussion. So what does this particular member of the B vitamins do, and why do we hear so much about it?
Well, for a start it’s different
Rather like a Death Metal fan at the Little Mix concert, B12 is a bit of an odd one out.
Perhaps the most unique of all the vitamins, B12 is the only molecule in the entire human body to contain the mineral cobalt, and is needed in only very small amounts as the body can store B12 more effectively than it can any other vitamin.
It’s also a right chunky monkey. A pretty hefty vitamin in terms of the number of atoms it contains (a whopping 181 – by contrast vitamin C has only 20 atoms), it took scientists a long old time to figure out how to synthesise it themselves. Despite being isolated in 1948, it was only in 1973 that B12 could be successfully made in a lab. Compare that with vitamin B3 (niacin), first manufactured in a lab back in 1867, and B12 is practically a spring chicken.
Where can we find it?
B12 is made by bacteria, and so plant eating animals only manage to produce B12 thanks to the microflora in their guts. This is true in humans too, where B12 can be made by our gut bacteria. Although we probably don’t produce as much B12 in the small intestine as our bodies need, it’s still a pretty cool achievement nonetheless.
B12 can only be found in animal foods, such as meat, fish and dairy, which is something vegans (and to a lesser extent vegetarians) need to be aware of. The British Dietetic Association recommends that vegans include foods fortified with Vitamin B12 in their diet, which typically include the following:
• yeast extract (eg. marmite)
• soya milk, yoghurts and desserts
• breakfast cereals
• certain brands of rice drinks and oat drinks.
Check the label to see if these foods have been fortified with B12, or consider taking a supplement if none of the brands or foods you eat as a vegan are fortified.
Why do we need it?
Playing a key role in blood cell formation, B12 also aids iron absorption, and both tissue growth and nerve cell maintenance. It's particularly important for growth when we're young, and also plays a part in controlling the appetite with its partner cobalt.
What happens if we don’t get enough?
B12 is a sort of ‘frenemy’ of folate or folic acid (B9), where both rely on the other for activation. Folate needs B12 in order to convert dietary folate into the active form of the vitamin. Similarly, the intriguing sounding ‘folate trap’ describes the situation where deficiencies of B12 and folate co-exist together, with folate masking B12 deficiencies.
B12 or B9 deficiency therefore occurs when a lack of vitamin B12 or folate causes the body to produce abnormally large red blood cells that can't function properly. This means not enough oxygen can be transported around the body by the haemoglobin in our red blood cells.
Symptoms include those typical of anaemia, such as general fatigue and tiredness, but B12 deficiency can also cause the following:
• pins and needles
• a sore, red tongue
• mouth ulcers
• muscle weakness
• disturbed vision
• psychological problems, which may include depression and confusion
• problems with memory, understanding and judgement
Mythbusting
Spirulina (an algae, and supplement du jour) is often cited as a bit of a miracle food, rich in pretty much every nutrient under the sun, including (supposedly) B12. This has been seized on by some as a potential non-animal source of B12 suitable for vegans. As the vitamin is the only one that is not recognised as being reliably supplied from a varied wholefood, plant-based diet with exposure to the sun, it's a bit of a problem for those following strict vegan diets.
What’s the truth? While spirulina is certainly nutrient dense, containing protein and non-haem iron alongside magnesium, potassium, and folate, most of the additional health claims made for it simply don’t stack up.
In terms of its B12 content, most of the B12 spirulina contains is actually a pseudo-vitamin, a B12 analog that looks very much like the real deal but can’t be used by the body in the same way. As a result, fortified foods and supplements (often a great deal cheaper than spirulina anyway!) are recommended for vegans.
Where do I find out more?
To find out exactly how much vitamin B12 we need, and for ideas of what to cook to make sure you’re getting B12 in your diet, take a look at B12’s vitamin biog here.
References
British Dietetic Association (2014) Food Fact sheet - Vegetarian diets.
http://www.b12-vitamin.com/algae/
http://www.nhs.uk/conditions/Anaemia-vitamin-B12-and-folate-deficiency/Pages/Introduction.aspx
Price, C. (2016) The Vitamin Complex. London, Oneworld Publications, pp. 260 -1.