What Are the Symptoms of Low Vitamin B12?

Reviewed on 2/2/2021

What Is Vitamin B12?

Anemia, fatigue, weakness and constipation are all hallmark symptoms of vitamin B12 deficiency.
Anemia, fatigue, weakness and constipation are all hallmark symptoms of vitamin B12 deficiency.

Vitamin B12 is a water-soluble vitamin required for red blood cell formation, nerve function, and DNA synthesis. 

A low level of vitamin B12 is called vitamin B12 deficiency.

What Are Symptoms of Low Vitamin B12?

Symptoms of low vitamin B12 (vitamin B12 deficiency) include: 

  • Anemia
  • Fatigue
  • Weakness
  • Constipation
  • Loss of appetite
  • Weight loss
  • Neurological changes, such as numbness and tingling in the hands and feet
  • Balance problems 
  • Depression
  • Confusion
  • Dementia
  • Memory problems
  • Soreness of the mouth or tongue
  • During infancy, signs of vitamin B12 deficiency include failure to thrive, movement disorders, developmental delays, and megaloblastic anemia 

What Causes Low Vitamin B12?

Most people in the U.S. get adequate amounts of vitamin B12, however, certain conditions can make some people more likely to develop vitamin B12 deficiencies, such as:

  • Being older 
  • Pernicious anemia
  • Reduced levels of stomach acidity (hypochlorhydria or achlorhydria)
  • Gastritis
  • Intestinal disorders
  • Autoimmune conditions
  • Vegetarians and vegans who consume no animal foods
  • Pregnant and lactating women who follow strict vegetarian diets and their infants
  • Certain medications that interfere with the absorption of vitamin B12

How Is Low Vitamin B12 Diagnosed?

Low vitamin B12 (vitamin B12 deficiency) is diagnosed with a blood test. 

Other tests may be needed to determine the cause.

What Is the Treatment for Low Vitamin B12?

Depending on the severity of the deficiency, low vitamin B12 (vitamin B12 deficiency) is treated with: 

  • Vitamin B12 injection
  • Oral vitamin B12 supplements
  • Consuming foods rich in or fortified with vitamin B12
    • Clams
    • Beef liver
    • Trout
    • Salmon
    • Canned tuna
    • Nutritional yeast
    • Beef
    • Milk
    • Yogurt
    • Cheese
    • Fortified cereals
    • Ham
    • Egg
    • Chicken

What Are Complications of Low Vitamin B12?

Complications of low vitamin B12 (vitamin B12 deficiency) include: 

  • Neurological problems, which may be irreversible
    • Vision problems 
    • Memory loss 
    • Pins and needles feeling
    • Loss of coordination 
    • Numbness and tingling of extremities 
  • Infertility
  • Stomach cancer
  • Neural tube defects, a type of serious birth defect

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Reviewed on 2/2/2021
References
https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/

https://www.nhs.uk/conditions/vitamin-b12-or-folate-deficiency-anaemia/complications/