Vitamin B12 deficiency can develop slowly, and some symptoms are easy to overlook. Because B12 is important for red blood cell production, nerve function, and brain health, a deficiency can affect many parts of the body.
Signs of Vitamin B12 Deficiency That Are Often Missed
- Unusual tiredness and weakness
- Feeling exhausted, low in energy, or weaker than usual may occur due to anemia caused by low B12.
- Numbness or tingling
- “Pins and needles” sensations, especially in the hands and feet, can happen when nerves are affected.
- Balance problems
- Nerve changes may lead to unsteadiness or difficulty walking.
- Memory or concentration difficulties
- Some people notice brain fog, forgetfulness, or trouble focusing.
- Mood changes
- Irritability, low mood, or symptoms that resemble depression can occur in some people.
- Pale or yellowish skin
- B12 deficiency can affect red blood cells and may change skin appearance.
- Sore, red, or swollen tongue
- A condition called glossitis can occur.
- Shortness of breath or dizziness
- These may result from anemia reducing the blood’s ability to carry oxygen.
- Vision changes
- Rarely, severe or prolonged deficiency can affect the optic nerve.
- Loss of appetite or weight loss
- Digestive symptoms can occur in some people.
Who may be at higher risk?
- Older adults
- People with absorption problems (such as certain stomach or intestinal conditions)
- People who have had some types of stomach or bowel surgery
- People taking certain medications (including some acid-reducing medicines or metformin)
- People following a strict vegan diet without B12 supplementation
When to get checked
If you have persistent symptoms—especially numbness, balance problems, memory changes, or unexplained fatigue—a healthcare professional can check B12 levels and related blood tests.
B12 deficiency is usually treatable, but long-standing nerve symptoms may not fully improve if treatment is delayed, so early evaluation is important.
