Vitamin B12 and folate: who runs short
Vitamin B12 or folate deficiency affects around 1 in 10 people aged 75 or over, the NHS says, and the most common cause of B12 deficiency in the UK is not diet.
The NHS’s guidance on B vitamins says adults aged 19 to 64 need about 1.5 micrograms of vitamin B12 a day. For folate, the figure is 200 micrograms. Most people with a varied diet should get both from food, it says, but B12 is not found naturally in fruit, vegetables and grains, so vegans may not.
Good sources of B12 are meat, fish, milk, cheese, eggs and some fortified breakfast cereals. For vegans, the NHS’s vegan diet page says sources are limited and a B12 supplement may be needed. Good sources of folate are broccoli, Brussels sprouts, leafy green vegetables such as cabbage, kale, spring greens and spinach, peas, chickpeas and kidney beans, liver (which the NHS says to avoid if you are pregnant) and breakfast cereals fortified with folic acid, the manmade form of folate.
Who can run short
The most common cause of B12 deficiency in the UK is pernicious anaemia, an autoimmune condition that stops the body absorbing B12 from food, according to the NHS’s page on deficiency anaemia. A lack of either vitamin in the diet is uncommon, it says, but can happen with a vegan diet and no supplements or fortified foods, a restrictive diet, or a generally poor diet for a long time. Certain medicines, including anticonvulsants and proton pump inhibitors, can affect how much the body absorbs.
Deficiency in either vitamin is more common in older people, the page says. It affects around 1 in 10 of those aged 75 or over.
Supplements, and what a test can miss
The NHS says taking 2mg or less a day of B12 in supplements is unlikely to cause harm, though there is not enough evidence to show what high doses may do. Folic acid in doses higher than 1mg can mask the symptoms of B12 deficiency, it says.
NICE’s guideline on B12 deficiency, published in March 2024, tells doctors to ask people about over-the-counter B12 products when testing, because they may raise test results without fully treating a deficiency.
How firm the evidence is
A 2018 Cochrane review of three trials with 153 people compared B12 tablets with injections. Its authors rated the evidence low or very low quality, and no trial reported on clinical signs and symptoms. The NHS’s B vitamins page was last reviewed in August 2020.
When to see a GP
The NHS says to see a GP if you think you may have a B12 or folate deficiency. It says deficiency anaemia should be treated as soon as possible, because although many symptoms improve with treatment, some problems can be irreversible. NICE notes that the symptoms of B12 deficiency may also be associated with many other conditions.
