What is vitamin B12 deficiency, and why can it mimic normal ageing?

Vitamin B12 is a nutrient the body needs only in microscopic amounts, yet a shortage can have major effects on health and energy. According to Science Daily, the vitamin was first linked to a lifesaving liver treatment, and its role in human health has been understood in ever greater detail since.

B12 is part of many essential processes in the body. It plays a role in producing red blood cells, in the healthy functioning of nerve cells and in making DNA. All of these processes are critical to the body working properly day to day, which is why even a small deficiency can lead to a wide range of symptoms.

The most insidious aspect of the deficiency is that its symptoms are often mistaken for normal ageing. Fatigue, weakness, forgetfulness, difficulty concentrating and a general sense of exhaustion can all be signs of both B12 deficiency and ageing. This overlap can allow the deficiency to continue undiagnosed for a long time.

B12 is found mainly in foods of animal origin: meat, fish, eggs and dairy. People who eat a mostly plant-based diet may therefore be at higher risk of deficiency unless they take a supplement. But insufficient intake is not the only cause.

With age, the body's ability to absorb B12 can decline. The stomach produces a substance needed to absorb the vitamin from the gut; when that production falls, the body may not absorb enough B12 even when enough is consumed. This makes the deficiency more common, particularly in older adults.

Some medicines can also affect absorption. Drugs that reduce stomach acid and some used to treat diabetes can lower B12 levels over the long term. People who take these medicines for a long time may therefore be advised to have their levels monitored.

Untreated severe deficiency can leave lasting effects on the nervous system. Tingling in the hands and feet, balance problems and memory difficulties are among the signs of advanced deficiency. The good news is that, when caught early, the deficiency can usually be corrected easily with supplements or dietary changes.

Diagnosis can be made with a simple blood test. Experts therefore recommend that people experiencing unexplained fatigue, memory problems or nerve symptoms — particularly if they are older or in a risk group — have their B12 levels checked.

Treatment varies according to the cause of the deficiency. For diet-related deficiencies, oral supplements are usually enough; for absorption problems, B12 given by injection may be needed. The right approach is determined by a health professional.

The story of B12 is an example of how small amounts can have large effects. A shortage of a vitamin needed only at microscopic levels can affect a broad range, from energy and mental clarity to nerve health — and although these symptoms may look like an inevitable part of ageing, they often have a treatable cause.