Vitamin B12 is needed by the body to make red blood cells, according to the NHS.
It’s also used to keep the nervous system healthy, and helps with the production of DNA.
Not getting enough of the vitamin can be very dangerous, and may lead to neurological or blood problems.
But, how can you spot when you’re at risk of a vitamin B12 deficiency?
These are the four warning signs of the condition to look out for.
“Vitamin B12 deficiency can be sneaky and harmful,” said Harvard Medical School.
“Vitamin B12 deficiency can be slow to develop, causing symptoms to appear gradually and intensify over time. It can also come on relatively quickly.
“Given the array of symptoms it can cause, the condition can be overlooked or confused with something else.
“While an experienced physician may notice the symptoms and be able to detect a vitamin B12 deficiency with a good interview and physical exam, a blood test is needed to confirm the condition.”
Early detection and treatment is crucial, it added, as the deficiency could lead to neurological problems or blood diseases.
One of the key warning signs of a vitamin B12 deficiency to look out for is any strange sensations in the body.
This can include a numbness or tingling in the hands, legs or feet.
A swollen or inflamed tongue could also signal the condition.
The swollen tongue could make it appear smooth, as the tastes buds may disappear.
Other warning signs of the deficiency include memory loss, and difficulty walking.
A deficiency could be caused by not getting enough vitamins in your diet, or by pernicious anaemia – where the body’s immune system attacks healthy stomach cells.
Top up on vitamin B12 by eating more beef, liver, salmon, egg or dairy foods.
See a GP if you’re worried that you may have a vitamin B12 deficiency.
Most cases can be easily treated with vitamin B12 supplements and diet changes.
It’s important for the condition to be diagnosed early, as it can lead to heart conditions and temporary infertility on rare occasions.