The medical community often emphasizes the importance of maintaining healthy levels of vitamin B12. This generally leads to a number of questions regarding this particular nutrient. Here’s a list of the most commonly asked questions about Vitamin B12.

1. What is Vitamin B12 and What Are the Benefits?

Vitamin B12, also referred to as cobalamin, is a water-soluble vitamin that supports the body’s ability to produce healthy red blood cells, nerves, and deoxyribonucleic acid (DNA).1 Additionally, this essential nutrient lowers the risk of experiencing anemia that causes weakness and fatigue.1 

There are different natural forms of B12, known as methylcobalamin, adenosylcobalamin, and hydroxycobalamin, as well as a synthetic form called cyanocobalamin.2 Humans are unable to produce vitamin B12 and must consume it through food or dietary supplements. This leads to the next question: Where does vitamin B12 come from?

Vitamin B12 is naturally found in animal foods that include:

  • Beef liver
  • Clams
  • Fish
  • Meat
  • Poultry
  • Eggs
  • Dairy

Liver and clams are described as two of the best sources of vitamin B12. The human body also happens to store ample amounts of this vitamin in the liver, followed by the kidney and the brain, which accumulate vitamin B12 as well.3

Certain foods, such as bread, plant-based milk, nutritional yeasts, and breakfast cereals are typically fortified with vitamin B12. Similarly, vitamin B12 is added to fortified dietary supplements such as Black Bear Energy Drink, which contains two forms of B12 (hydroxocobalamin and adenosylcobalamin) for enhanced absorption and health benefits. 

Cyanocobalamin, which is the form of vitamin B12 that is often found in most commercially available supplements, has not been added to Black Bear Energy Drink. CyanoB12 contains a cyanide molecule. So, when you take cyanoB12 your body must first turn it into hydroxyB12 in order to use it and then must find a way to get rid of the toxic cyanide molecule. Cyanide is a poison even if the rest of the B12 molecule is good for you. The body actually uses hydroxyB12 in order to detoxify cyanide. So, not only is cyanoB12 not the form your body ultimately needs, but taking higher doses of cyanoB12 may actually deplete your hydroxy B12. So why would anyone use cyano B12 if it can be toxic? Well, in low doses it may be helpful for the eyes, but for the most part cyanoB12 is used because it is much less expensive and a form of B12 that is easier to keep stable.

Now let’s take a look at some additional questions that are commonly asked.

2. Do I Need to Take Vitamin B12 Every Day and How Much Should I Take?

According to the National Institutes for Health (NIH), the recommended daily intake depends on your age, with children over the age of four and adults needing at least 2.4 micrograms a day.4 Women who are pregnant or nursing need 2.8 micrograms a day, while infants and young children under the age of four only need 0.5-0.9 micrograms daily.

So, can you overdose on vitamin B12? Thankfully, vitamin B12 has a low level of toxicity when it is consumed orally, with studies showing that it can be taken safely at even high servings of 2,000 micrograms.5 However, vitamin B12 injections of 1,000 micrograms may cause allergic skin reactions.6 Furthermore, people who suffer from chronic kidney problems may experience a worsening of kidney-related health issues if they consume high servings of vitamin B12 (1,000 micrograms) daily.6

3. What Causes a Vitamin B12 Deficiency?

There are several factors that put some people at risk of a vitamin B12 deficiency. This health issue is more frequently observed in the following individuals8:

  • People who are on a strict vegan diet
  • Elderly individuals, particularly those with pernicious anemia
  • Individuals who had parts of the intestine or bowel surgically removed
  • People whose bodies don’t properly absorb nutrients due to alcohol abuse
  • People who take certain prescription medications (e.g., metformin, antacids)
  • Individuals whose diet contains minimal or no natural food sources of vitamin B12   
  • Pregnant women who are not consuming a multivitamin or other sources of vitamin B12

Pernicious anemia is particularly problematic because in such cases, an individual may consume sufficient amounts of B12 (about 2.4 micrograms daily), but struggle to efficiently absorb it.9 There are two key processes that facilitate the absorption of vitamin B12 from food. The first process involves the exposure of food to hydrochloric acid in the stomach, which releases vitamin B12 from the food protein it is attached to. Next, vitamin B12 binds to a protein that is produced in the stomach, called intrinsic factor. It is this protein that promotes the absorption of vitamin B12. Unfortunately, people who have pernicious anemia do not produce enough intrinsic factor and their bodies struggle to absorb vitamin B12 from food or dietary supplements.9 This can lead to a vitamin B12 deficiency. 

While a vitamin B12 deficiency can often be addressed by taking the recommended daily value of 2.4 micrograms a day, individuals who have pernicious anemia benefit from a minimum of 1,000 micrograms daily.10

4. What Signals Indicate a Vitamin B12 Deficiency?

The signs of a vitamin B12 deficiency include:

  • Fatigue
  • Weakness
  • Dizziness
  • Pale skin
  • Diarrhea
  • Confusion
  • Irritability
  • Paranoia
  • Forgetfulness
  • Trouble walking
  • Muscle weakness
  • Loss of appetite
  • Shortness of breath
  • Rapid heart rate or an irregular heartbeat
  • Tingling, burning, or numbness in the limbs 

Furthermore, any individual who experiences a vitamin B12 deficiency has an increased risk of developing a specific form of anemia called megaloblastic anemia.11 In the absence of adequate B12 levels, cells do not grow or divide properly. This includes red blood cells that become large, fragile, and wedged in bone marrow.11 These large red blood cells cannot be transferred to the blood circulation, leading to anemia by lowering the amount of red blood cells that circulate throughout the body. 

The cells’ fragility also causes them to break down and this process releases excess bilirubin, which is a substance produced naturally in the body to break down old blood cells. As the levels of bilirubin increase, the skin may develop a yellow color.11 Therefore, megaloblastic anemia is associated with weakness, fatigue, and pale-looking skin.

5. Can I Take a Test to Determine My Level of Vitamin B12 Deficiency?

A blood test can help a health care professional identify a vitamin B12 deficiency. The test results demonstrate whether the measured vitamin B12 level falls within the low, normal, or high range. A health care provider can also assess the degree of the deficiency based on the B12 value that is obtained from the blood test results.

6. When Should I Notice the Health Benefits of Taking Vitamin B12?

Individuals’ bodies vary in terms of the manner in which vitamin B12 is absorbed. However, health benefits may be experienced anywhere from one week to several weeks after beginning B12 supplementation, depending on the degree of deficiency.11 If your health does not gradually improve, you may need to speak with a health care professional who can determine if your daily serving of vitamin B12 needs to be adjusted.


  1. Herrmann W, Rima O. Cobalamin deficiency. Subcell Biochem. 2012;56:301-22.
  2. Paul C, Brady DM. Comparative Bioavailability and Utilization of Particular Forms of B12 Supplements With Potential to Mitigate B12-related Genetic Polymorphisms. Integr Med (Encinitas). 2017;16(1):42-49.
  3. Markle HV. Cobalamin. Crit Rev Clin Lab Sci. 1996;33:247-356.
  4. National Institutes of Health (NIH). Daily Values Tables: For vitamins and minerals, all age categories. Retrieved from:
  5.  Wang H, et al.Oral vitamin B 12 versus intramuscular vitamin B 12 for vitamin B 12 deficiency. Cochrane Database Syst Rev. 2018;3(3):CD004655.
  6. Brescoll J, Daveluy S. A review of vitamin B12 in dermatology. Am J Clin Dermatol. 2015;16(1):27-33. 
  7. House AA, et al. Effect of B-vitamin therapy on progression of diabetic nephropathy: a randomized controlled trial. JAMA. 2010;303(16):1603-9.  
  8. Watanabe F, et al. Biologically active vitamin B12 compounds in foods for preventing deficiency among vegetarians and elderly subjects. J Agric Food Chem. 2013;61(28):6769-75.
  9. Bizzaro N, Antico A. Diagnosis and classification of pernicious anemia. Autoimmun Rev. 2014;13(4-5):565-8. 
  10. Chan C, et al. Oral Vitamin B12 Replacement for the Treatment of Pernicious Anemia. Front Med (Lausanne). 2016; 3: 38. 
  11. Aslinia F, et al. Megaloblastic anemia and other causes of macrocytosis. Clin Med Res. 2006;4(3):236-41