"Meat, eggs, fish and dairy products are the primary dietary sources of vitamin B12," says Priya Tew, a registered dietitian and founder of Dietitian UK. "If you don't eat meat or dairy and you follow a vegan or vegetarian diet, you certainly need to be aware of the risk of a deficiency."
Recent estimates from the National Institute for Health and Care Excellence (Nice) suggest that B12 deficiency affects 11 per cent of vegans. Older people are also more at risk. Overall, B12 deficiency affects about 6 per cent of people under 60, and 20 per cent of those over 60.
"When we get older our appetites dwindle, so we may consume less food containing vitamin B12. We are also less able to absorb it effectively," says nutritionist Rhiannon Lambert, author of The Science of Nutrition. "Older women may also be at a higher risk of a vitamin B12 deficiency due to their increased likelihood of getting the auto-immune condition pernicious anaemia, which causes your immune system to attack the cells in your stomach that produce the intrinsic factor – a protein that helps your intestines absorb vitamin B12.
"Other at-risk groups include those who have had abdominal or bowel surgery, and anyone who takes long-term antacid drugs for heartburn."
However, if you eat meat, eggs and dairy, it's likely you will still be getting your fair share of B12 and probably don't need to worry. "If your absorption isn't completely efficient, it's likely to be less of a problem than if you're vegan or a vegetarian to boot," says Tew. "But it's worth speaking to your doctor if you're concerned about the amount of vitamin B12 in your diet, or your body's ability to absorb it."
Early symptoms of a deficiency include tiredness, fatigue and mood changes. But if a vitamin B12 deficiency is left unchecked, things could get more serious. "Eventually, you can get a form of anaemia known as megaloblastic anaemia, which is different to the type caused by iron deficiency," says Tew. "A B12 deficiency can also affect fertility and increase the risk of neural tube defects like spina bifida in babies during pregnancy." In extreme cases vitamin B12 deficiency has also been linked to nerve damage and cardiovascular disease.
Fortunately, even if you're vegan, or just prefer to eat less meat and dairy, there are still plenty of ways you can bolster your vitamin B12. "Breakfast cereals and plant milks, like almond and soya, are often fortified with B12 and, love it or hate it, Marmite is also high in vitamin B12. Nutritional yeast flakes fortified with vitamin B12 are another good way to up your intake. Simply sprinkle them over salads, pasta or rice."
So how much do we need in our daily diet? The NHS recommends that adults aged 19 to 64 need about 1.5 micrograms a day of vitamin B12. (A microgram, mcg, is one thousandth of a milligram, mg).
"Sticking to this recommended daily intake of vitamin B12 can help improve your mood and energy," says Tew, who suggests reading the information on your cereal box or plant milk packet to check the quantities.
But what about supplements? If we're in an at-risk group, should we be popping a pill?
"Although it is possible to get enough vitamin B12 through diet alone, whether you're plant-based or not, supplements are also a great way to ensure you get the recommended daily amount, whether in spray, powder or tablet form," says Tew.
Lambert advises consulting your doctor or a registered nutritionist or dietitian before taking a supplement, but when it comes to vitamin B12, Tew says you don't need to worry too much about exceeding the recommended daily intake.
"B12 is a water-soluble vitamin, so the kidneys process them and any excess is flushed from the body in the urine. With some vitamins, you need to be more careful. If you take too much vitamin C, it can lead to a stomach ache and taking too many vitamin D supplements over a period of time can lead calcium to build up in the body, which can be dangerous and, according to the NHS, it can weaken the bones and damage the kidneys and the heart."
Daily diet and supplements aside, you'll need a healthy gut and a good volume of stomach acid to efficiently absorb the nutrient. Aside from the diabetes drug metformin, which hinders absorption of vitamin B12 in the bowel, other medications like omeprazole, which depletes stomach acid and is widely used to treat indigestion, heartburn, acid reflux and stomach ulcers, can put you at risk of deficiency. If you are concerned, ask your doctor for a blood test – a GP will be able to organise the appropriate tests to determine if you are deficient.
