3. Problems With Balance or Walking
Some people with significant B12 deficiency develop problems with coordination and balance.
You might notice:
Feeling unusually unsteady
Difficulty coordinating movements
Trouble walking normally
Increasing tendency to stumble
Neurological symptoms deserve prompt medical attention because prolonged deficiency can sometimes cause lasting nerve damage.
4. Memory and Concentration Problems
Vitamin B12 deficiency can sometimes affect cognitive function.
Possible symptoms include:
Poor concentration
Forgetfulness
Confusion
Difficulty thinking clearly
Problems with memory or judgment
Severe deficiency can occasionally produce significant neurological or psychological symptoms. However, memory problems have many possible causes, and B12 deficiency should not be assumed without proper evaluation.
5. Pale Skin and Heart Palpitations
B12 deficiency can cause megaloblastic anemia, a condition in which abnormal red blood cells are produced.
Possible signs include pale skin, weakness, tiredness, and heart palpitations.
Palpitations can also have many unrelated causes, so recurring or concerning episodes should be medically assessed.
6. A Sore or Red Tongue
Changes inside the mouth can occasionally provide another clue.
Vitamin B12 deficiency may cause glossitis, in which the tongue becomes sore, inflamed, or unusually red. Mouth soreness can also occur.
Because these symptoms can result from many conditions, they are most meaningful when they occur alongside other signs of deficiency.
7. Loss of Appetite or Unexplained Weight Loss
Some people with B12 deficiency experience reduced appetite and unintended weight loss.
These symptoms are nonspecific, meaning many medical conditions can cause them. Persistent unexplained weight loss should therefore be discussed with a healthcare professional rather than assumed to be a vitamin problem.
8. Mood or Psychological Changes
Vitamin B12 deficiency can affect the nervous system and, in some cases, may be accompanied by psychological symptoms.
These may include:
Low mood
Anxiety
Irritability
Confusion
More severe deficiency can sometimes be associated with significant cognitive or psychological changes.
Mental-health symptoms should never be assumed to result solely from a vitamin deficiency.
9. Vision Problems
Vitamin B12 deficiency can occasionally affect neurological pathways related to vision.
Vision changes are less common than fatigue or tingling, but the NHS lists visual problems among possible complications of B12 deficiency.
Sudden or significant changes in vision require prompt medical evaluation.
Who Is More Likely to Develop Vitamin B12 Deficiency?
Several factors can increase the likelihood of deficiency.
People following vegan or highly restrictive diets
Because naturally occurring B12 is found primarily in animal-derived foods, people who avoid these foods generally need reliable fortified foods or supplementation.
People who cannot absorb B12 properly
A person may consume adequate B12 and still become deficient.
Conditions affecting absorption can include autoimmune gastritis or pernicious anemia, gastrointestinal disorders, and certain types of stomach or intestinal surgery.
Older adults
Absorption of food-bound vitamin B12 can become less efficient with age, making deficiency more likely in some older adults.
People taking certain medications
Long-term use of some medications can interfere with B12 absorption. Examples documented by the NIH include metformin and proton-pump inhibitors.
Do not stop prescribed medication because of this possibility. A healthcare professional can determine whether testing or supplementation is appropriate.
How Is Vitamin B12 Deficiency Diagnosed?
Symptoms alone are not enough to confirm B12 deficiency because many of them overlap with other conditions.
Diagnosis usually involves your symptoms, medical history, examination, and blood tests. Additional testing may sometimes be required to identify why the deficiency developed.
Finding the underlying cause matters because treatment may differ depending on whether the problem comes from diet or impaired absorption.
Can You Simply Take a Vitamin B12 Supplement?
Not always.
Diet-related deficiency may sometimes be treated with oral vitamin B12, while people who cannot absorb B12 normally may require a different treatment approach. NICE guidance recommends choosing oral or intramuscular replacement according to the underlying cause and clinical circumstances.
Taking supplements without investigating persistent neurological symptoms can also delay diagnosis of another condition.
Food Sources of Vitamin B12
Foods naturally containing B12 include:
Fish and seafood
Beef and other meats
Poultry
Eggs
Milk
Yogurt
Cheese
People who avoid animal products can obtain B12 from appropriately fortified foods or supplements.
Importantly, increasing dietary intake will not necessarily correct a deficiency caused by poor absorption.
Why Early Recognition Matters
Vitamin B12 deficiency is often treatable, particularly when identified early.
However, neurological problems caused by prolonged deficiency can sometimes become irreversible. The NHS therefore advises seeking medical evaluation when B12 deficiency is suspected rather than allowing symptoms to continue untreated.
Pay particular attention to combinations of symptoms such as persistent fatigue together with tingling, balance problems, memory changes, or muscle weakness.
The Bottom Line
Vitamin B12 deficiency can begin quietly. Fatigue, weakness, tingling, numbness, balance problems, memory changes, a sore tongue, pale skin, or appetite changes can all occur, although none of these symptoms proves that B12 deficiency is the cause.
The safest approach is not to self-diagnose. If symptoms persist—especially neurological symptoms such as numbness, balance difficulties, confusion, or weakness—speak with a healthcare professional about appropriate testing.
Identifying the cause early can make treatment more effective and may help prevent potentially lasting complications.
