“Some people don’t consume enough vitamin B12 to meet their needs, while others can’t absorb enough, no matter how much they take in,” said the Harvard Medical School.
“As a result, vitamin B12 deficiency is relatively common, especially among older people.
“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 a vitamin B12 deficiency can cause, the condition can be overlooked or confused with something else.”
source: express.co.uk