B12 deficiency symptoms may be mistaken for aging

Vitamin B12 deficiency can produce fatigue, weakness, tingling, balance problems and memory issues that may be confused with ordinary aging, according to The Conversation. The concern is practical: researchers say some effects may appear before the anemia doctors have long used as a warning sign.

The body needs only tiny amounts of the vitamin. The Conversation reported that adults require roughly two micrograms a day, depending on the guideline, to support red blood cells, nerve function and DNA production.

B12 is found mainly in animal-derived foods such as meat, fish, eggs and dairy, The Conversation said. That puts vegans and vegetarians at higher risk unless they use fortified foods or supplements, while older adults and people with absorption problems also face increased risk.

Why deficiency can be missed

The NHS says vitamin B12 or folate deficiency anemia can have several causes, including diet and conditions that affect absorption. The Conversation reported that absorption can decline with age because some older people make less stomach acid, which helps release B12 from food.

Autoimmune gastritis can also damage stomach cells involved in making acid and intrinsic factor, a protein needed for B12 absorption, according to The Conversation. Weight-loss surgery and some medicines used for diabetes or acid reflux can reduce absorption as well.

The symptoms can build slowly. The Conversation listed exhaustion, weakness, shortness of breath, numbness or tingling in the hands and feet, poor balance, memory problems and “brain fog” among possible signs. It cautioned that these symptoms are not specific to B12 deficiency, so persistent tiredness, tingling or balance trouble should be assessed rather than treated as proof of a vitamin problem.

Beyond anemia

Doctors have long linked B12-related tiredness to anemia. Without enough B12, The Conversation said, bone marrow can release unusually large, immature red blood cells that do a poorer job carrying oxygen through the body.

Researchers are also studying another pathway: mitochondria, the structures inside cells that help turn food into usable energy. The Conversation reported that B12 is directly required by only two human enzymes, including one involved in mitochondrial processing of certain fats and protein building blocks.

A 2026 study cited by The Conversation found that low B12 interfered with mitochondrial DNA and reduced energy production in laboratory models of skeletal muscle. A related study in aged female mice found that B12 supplementation improved several measures of mitochondrial health in muscle, including the number and structure of mitochondria.

Those findings may help explain why some people with low B12 report fatigue before clear anemia is found, The Conversation said. The evidence does not show that B12 supplements reverse aging or raise energy in people whose levels are already normal.

A century-old medical clue

The modern story of B12 traces back nearly 100 years. The Conversation reported that George Minot and William Murphy showed in 1926 that a liver-rich diet could treat pernicious anemia, then often fatal. Earlier work by George Whipple had shown that liver helped dogs recover from anemia caused by blood loss, pointing scientists toward liver as a source of a blood-forming factor.

That work eventually led researchers to isolate cobalamin, the deep red compound now known as vitamin B12, according to The Conversation.

For treatment, the NHS uses hydroxocobalamin injections for vitamin B12 deficiency anemia. The Conversation reported that injections are an established treatment for diagnosed deficiency, especially when absorption is impaired, but there is little evidence that B12 shots improve energy, weight loss or performance in people with normal B12 levels.

This story draws on original reporting from ScienceDaily.