By Katherine Watt 

Vitamin B12 is one of eight essential B vitamins and is manufactured by living organisms such as bacteria, yeasts and algae. It’s found in the largest quantities in animal products, including meat, eggs and milk – this is because animals drink water and eat food containing B12-making organisms. It’s also added to fortified foods such as nutritional yeast, milks and cereals.

In your body, B12 is needed for millions of cellular processes every second. ‘Specifically, it works alongside B9 in the process of methylation, which helps you detoxify harmful substances from your body,’ says functional medicine coach Fran McElwaine (

Proper methylation prevents the build-up of a harmful substance called homocysteine, which has been linked to heart disease and cognitive decline, and also helps your body make feelgood hormones serotonin and dopamine.

Oxygen delivery

B12 also plays an important role in circulation and the delivery of oxygen in the body, which is why getting healthy levels revs up your energy. It’s also involved with red blood cell production. Not only does this slow down if there’s not enough B12 in your body, but ‘very low levels can cause red blood cells to enlarge,’ adds Fran.

‘This increase in size means the cells can’t travel into smaller capillaries.’ One area of your body to suffer as a result of this would be the maculas in your eyes, which have tiny capillaries. ‘It can also set up problems in the brain and lead to nerve damage.’
The recommended daily intake of B12 is at least 1.5mcg, although The Vegan Society says 3mcg is better.

Your body can store up to 5mg of B12 in your liver, which can last for years if you don’t stress yourself with excessive alcohol, sugar, cigarette smoke and other environmental toxins. Pregnancy and breastfeeding also accelerate the depletion of B12.

Notice if you don’t have enough B12

What’s more, it’s easy not to notice if you become deficient. For starters, the noticeable symptoms of mild B12 deficiency are also prevalent in modern-day society: tiredness, depression, memory loss and headaches. Other effects, including the build-up of harmful homocysteine, are symptomless.
It’s estimated around six per cent of the population under 60 is deficient. This rises to 20 per cent in those aged over 60. And deficiency isn’t always down to not eating enough B12-rich foods but from not being able to properly absorb the vitamin.

‘B12 has to be extracted from food and reach your intestines to be assimilated, which requires two things: enough stomach acid and a substance called “intrinsic factor”, which helps B12 during its journey. Production of both often decreases as we get older, which is why B12 deficiency increases too,’ says Fran.

Test your levels

Deficiency can also take a long time to develop. While you can get your blood levels of B12 measured, this doesn’t always paint the most accurate picture. ‘A better measure is known as the Mean Corpuscular Volume test. This directly measures the size of your red blood cells,’ says Fran. A naturopath or nutritionist can order this test for you and can interpret the results to create a specific nutrient plan moving forward.

Are you on a PPI?

PPIs – proton pump inhibitors – are one of the most commonly prescribed medications in the UK. They are designed to reduce symptoms of reflux by reducing stomach acid. However, this can affect your B12 levels.
One study suggested there is a 65 per cent greater chance of B12 deficiency in people taking PPIs for more than two years. Metformin, which is used to treat type 2 diabetes, also interferes with B12 production as it reduces your ability to make intrinsic factor. ‘If you’re over 50 and/or taking either of these medications, you might want to supplement with B12,’ says Fran.

A note for vegans

Plant foods contain virtually no B12 so vegans can easily become deficient. This could affect around 11 per cent of vegans. If you are vegan it’s essential you get enough B12 from either a supplement or fortified foods. ‘If relying on fortified foods, aim for at least 3mcg per day spread across a minimum of two meals. For example, make porridge with 200ml of fortified plant milk then add a tablespoon of fortified nutritional yeast flakes to your dinner,’ says Heather Russell, dietician for The Vegan Society. ‘A daily supplement needs to contain at least 10 micrograms (mcg) of B12 whereas a weekly supplement should provide at least 2000mcg.’

Some supplements come from animal sources so make sure the one you pick is vegan certified. The Vegan Society suggests products containing cyanocobalamin, a synthetic type of B12. ‘This is the type that researchers use and we have plenty of evidence it works,’ says Heather. Try VEG1 (from £6.60,

Maximise your B12 levels

As well as supplementing, there are other ways to maximise your B12 levels, says Fran McElwaine…
  • Eat more fortified foods. There’s some evidence that B12 in fortified foods gets into your system more easily than that in animal products, such as meat and dairy. Add fortified nutritional yeast, breakfast cereals and milks.
  • Improve your digestion. Chew your food well and avoid drinking at meal times, as the fluid dilutes stomach acid. It’s best to drink at least 30 minutes either side of a meal.
  • Drink apple cider vinegar. Sip 30ml of apple cider vinegar in 200ml of water before meals to help support acid production.
  • Look after your gut. Bacteria play an important role in metabolising B12 in your intestine. Eat plenty of fermented foods such as kimchi, kefir and kombucha.
  • Check your meds. If you’re on PPIs, check with your doctor whether you still need to take them. ‘They’re great for short periods but people often use them for far too long,’ says Fran.