Vitamin B12 deficiency: signs and symptoms

B vitamins – iStock
B vitamins – iStock

There is a good chance that you might not be getting enough vitamin B12 - it's estimated that up to 20% of the general population are deficient in Vitamin B12.

Vitamin B12 is a water soluble, essential vitamin which cannot be stored in the body or manufactured by it.

What B12 does in the body

  • Promotes growth in children and teenagers.
  • Helps maintain a healthy nervous system by playing a vital role in the formation and maintenance of the myelin sheath, a protective layer around each nerve.
  • Assists in the formation of red blood cells.
  • Helps to promote a healthy appetite in young people.
  • Ensures normal growth.  

Because the body cannot make it by it’s self, or at least no as much as we need, this vital vitamin must be obtained from external sources like food and supplements.

The current recommended dietary allowance (RDA) for vitamin B12 is 2.4 mcg (micrograms) per day. 

Read: B12 – the forgotten B vitamin?

Foods that contain vitamin B12

People at risk for B12 deficiency

According to Harvard Health Publications strict vegetarians and vegans are at high risk for developing a B12 deficiency (because it is found largely in animal products). People who have undergone any form of bariatric surgery are also likely to be low in vitamin B12 because this interferes with the body’s ability to extract vitamin B12 from food.

Test yourself: Is my vegetarian diet balanced?

Conditions that interfere with nutrient absorption, like coeliac or Crohn’s disease, can cause B12 deficiency, as can heartburn drugs which reduce acid production in the stomach. This happens because acid is needed to absorb vitamin B12. It can also occur in older people because of lower stomach acid production.

Scientist have also found a clear link between a lack of vitamin B12  and peripheral neuropathy, a term describing any disorder of the peripheral nerves, which carry information to and from the brain and spinal cord.

Signs and symptoms of B12 deficiency

B12 deficiency symptoms can manifest gradually or quickly and are often confused with other conditions. Symptoms include:  

  • Fatigue
  • Weakness
  • Hallucinations or paranoia
  • Impaired cognitive processes (trouble thinking)
  • Yellow skin
  • Swollen, inflamed tongue
  • Anaemia
  • Struggling with balance and walking
  • Tingling sensations or feelings of numbness in the feet, hands or legs

If you think you may be deficient in B12, ask your doctor to request a blood test. If a deficiency has contributed to blood diseases or neurological problems, it is important that it is diagnosed as soon as possible.

Read more:

Vitamin B12 supplements may be the answer for some

Acid-reflux meds tied to B12 deficiency

To B12 or not B12?


Health24: Vitamin B12 (cobalamin) (2013). 4

Harvard Health Publications: Vitamin B12 deficiency can be sneaky, harmful (2013).

Centre For Peripheral Neuropathy, University of Chicago

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