Vitamin B12 (also referred to as cobalamin or cyanocobalamin) is an important nutrient that your body requires to help optimize brain, nerve, and blood health. However, despite its importance, there's plenty of evidence showing that people around the world are deficient in this essential nutrient.   

Studies from the United States demonstrate that up to one in six (17 percent) of those aged 60 and older are deficient in Vitamin B12 while upwards to one in 15 (six percent) of those under age 60 are deficient. But, this isn't just a health concern for Americans. In the northern part of China, for instance, a 2014 study showed up to 45 percent of Chinese women were deficiency in vitamin B12.  Many other countries are also affected.

Signs and Symptoms of B12 Deficiency

Due to vitamin B12’s importance to the human body, various problems can occur when a person has insufficient stores. Symptoms include anemia, memory issues, and depression according to a Harvard University.  A vitamin B12 deficiency can result in the following conditions:

  • Anemia  
  • Abnormal platelet count (low platelets or elevated number of platelets)
  • Burning tongue (burning mouth syndrome)
  • Depression
  • Fatigue
  • Hallucinations and confusion
  • Insomnia
  • Loss of balance
  • Loss of smell
  • Memory loss – Vitamin B12 deficiency is more common in those with dementia
  • Numbness and tingling in legs and arms, referred to as "peripheral neuropathy" by doctors. Neuropathy is common in those with diabetes but may also affect those with prediabetes or no diabetes.  
  • Ringing in the ears (tinnitus)
  • Vitiligo – A skin condition where sections of the skin lack color (hypopigmentation)

Sources of Vitamin B12

Food is an important source of Vitamin B12. These are primary sources within the diet:

  • Meat, poultry, fish, eggs and dairy products
  • Spirulina, a blue-green algae, is rich in vitamin B12

Testing for Vitamin B12

Testing for vitamin B12 blood levels—the most common way of testing is through a blood test—can be easily ordered by your physician. Values that are considered normal may vary by country, but here are some recommendations to consider:  

  • Vitamin B12 blood level (normal is 200 to 900 pg/ml) – Most neurologists recommend blood levels above 500 pg/ml to ensure the nerves and brain have adequate amounts.
  • Methyl malonic acid – An elevated level demonstrates vitamin B12 levels are insufficient.
  • Homocysteine – An elevated level demonstrates vitamin B12 levels are insufficient.  Elevated homocysteine levels can also be present in those with folic acid deficiency.  Elevated homocysteine levels increase risk for dementia and cardiovascular disease.

Nine Benefits of Vitamin B12

Vitamin B12 has many functions. Here are some of its most important functions:

  • Improves Fatigue
  • Optimizes memory function
  • Optimize sleep
  • Helps make red blood cells
  • Involved in DNA synthesis
  • Helps with protein production
  • Help with production of brain chemicals (neurotransmitters) to prevent depression
  • Improves nerve function and communication
  • Lowers homocysteine levels – Elevated levels of the amino acid homocysteine are associated with increased risk of dementia, heart disease, and stroke.  Vitamin B12 lowers homocysteine.

Vitamin B12 Deficiency Risk Factors

There are many risk factors for vitamin B12 deficiencies. Consider getting your blood levels tested if any of these pertain to you:

  • Age – As you age, your gastrointestinal tract's ability to absorb vitamins and minerals decreases. As a result, supplementation of essential vitamins is crucial.
  • Vegetarian diet – Meat is a main source of vitamin B12, so if you're a vegetarian, it's important to take a vitamin B12 supplement or equivalent.
  • Pernicious anemia – Diagnosed when red blood cells are low due to the absence of vitamin B12, pernicious anemia affects one in 1,000 people. The main symptom is fatigue.
  • Crohn’s disease – An autoimmune disease that results in colon inflammation, which results in decreased absorption of important nutrients.
  • Alcohol consumption – Regular consumption of alcohol results in reduced absorption of vitamin B12, folic acid, and thiamine.
  • Gastric surgery – those who undergo weight loss surgeries frequently will have mal-absorption issues of vitamin B12 among other vitamins.

Medications That Cause Vitamin B12 Deficiency

  • Acid-reducing medications – Omeprazole (Prilosec), pantoprazole (Protonix), esomeprazole (Nexium), ranitidine (Zantac) and famotidine (Pepcid).
  • Diabetic medication – Metformin reduces absorption of vitamin B12. A 2014 study from South Korea showed patients who took 1,000 mg of metformin per day were 10 times more likely to be deficient in vitamin B12 than those not taking the medication.   
  • Birth control pills
  • Chronic steroid use
  • Antibiotics – Taking antibiotics can destroy gut bacteria, which manufacture vitamin B12.
  • Cholestyramine – A cholesterol-lowering drug
  • Seizure medications such as phenytoin
  • Gout medication (colchicine)
  • Potassium citrate and potassium chloride

How to Prevent Deficiencies

Helping your body maintain adequate vitamin B12 levels can be as simple as taking a vitamin B12 or Spirulina (Read Health benefits of Spirulina) supplement for some.


A few things to remember:  If a folic acid deficiency is also present, replace vitamin B12 first, then replace folic acid.  This helps with cell  metabolism.  Since vitamin B12 is water soluble, it can leave the body quickly when one urinates (vitamin B12 will make the urine bright yellow). Consider taking this vitamin twice per day to help keep blood levels optimal.

There are a few ways to consume vitamin B12:

  • Vitamin B12 tablets – Available as vitamin B12 (cyanocobalamin) or methyl-vitamin B12 (methylcobalamin).  Daily oral dose ranges from 500 mcg to 5,000 mcg.
  • Vitamin B12 oral spray – Daily oral dose ranges from 500 mcg to 5,000 mcg.
  • Vitamin B12 liquid drops – Available as vitamin B12 (cyanocobalamin) or methyl-vitamin B12 (methylcobalamin). Daily oral dose ranges from 500 mcg to 5,000 mcg.
  • Vitamin B12 injections – Must be prescribed by a physician in most countries. 1,000 mcg can be injected weekly or once per month.


Vitamin B12 deficiency is one of the more common types of vitamin deficiencies. When low, many symptoms can result in the affected person. Routine vitamin B12 testing should be conducted, especially in those over age 60 and in those on medications such as acid reducers, birth control pills, and diabetic medication.  Most who are deficient need vitamin B12 supplementation.  


  1. Students show 17% of those 60 and older are vitamin B12 deficient, page 62, Accessed October 29, 2017
  2. Dang S, Yan H, Zeng L, et al. The Status of Vitamin B12 and Folate among Chinese Women: A Population-Based Cross-Sectional Study in Northwest China. Sengupta S, ed. PLoS ONE. 2014;9(11):e112586. doi:10.1371/journal.pone.0112586. Accessed October 17, 2017
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