What Is Vitamin B-12?

by Dr. Edward Group DC, NP, DACBN, DCBCN, DABFM Published on , Last Updated on

An individual running through the field. Your body doesn’t make vitamin B-12, you can get it from supplementation or diet.Vitamin B-12, also known as cobalamin, is an essential nutrient that is a member of the B-complex vitamins. B-12 is the largest and most structurally complex of all known vitamins. There are several forms of vitamin B-12, all of which are termed “cobalamins” because they contain the trace mineral cobalt in their nucleus structure. Some forms of B-12 are not immediately bioavailable and your body must use enzymes to convert them to a usable form. However, methylcobalamin and hydroxocobalamin (5-deoxyadenosylcobalamin) forms are highly bioavailable.

Where Can You Get Vitamin B-12

Your body doesn’t make vitamin B-12, you need to get it through your diet or by supplementation. It’s found mostly in foods of animal origin such as meat, fish, and eggs. Even though only bacteria and archaea can synthesize B-12, animals integrate B-12 into their tissues via bacterial symbiosis, which is why animal foods are naturally the richest source of B-12. Fortified foods and supplements are also common sources of the nutrient.

Why You Need Vitamin B-12

Vitamin B-12 plays an important role in a number of ways. The body functions that rely on adequate B-12 include:

  • Brain and nervous system health via myelin sheath function
  • DNA synthesis
  • Red blood cell formation
  • Healthy cell metabolism (of nearly every cell in your body)
  • Cardiovascular health

Individuals with the MTHFR gene mutation may be at a higher risk for elevated homocysteine levels. When homocysteine levels are higher than normal, osteoporosis, blood clots, and atherosclerosis are common symptoms. Dietary intervention via vitamin B-12 supplementation (as well as folate and B6) is necessary for bringing homocysteine levels back into balance. [1]

How Much Vitamin B-12 Do You Need?

The Institute of Medicine and Food and Nutrition Board — the premiere scientific health bodies officially sanctioned by the U.S. government on matters of nutrient intake — set daily recommendations of vitamin B-12 for normal adults at 2.4 mcg/day, with up to 3 mcg/day for pregnant and lactating women. [2]

Keep in mind these numbers are absolute minimums. Research suggests that average vitamin B-12 intake among the U.S. population is ~3.4 mcg/day, clearly above the adequate recommended daily intake. [3] Regardless, due to digestion and absorption issues, disease status, and prescription medication interference, some data suggests a sizable number of the population is B-12 deficient.

The typical human body can absorb up to 1.5 mcg of vitamin B-12 from food, but supplementation has been shown to allow for higher absorption rates by bypassing the digestive process. Although some will tell you that humans store between 2 to 5 mg of vitamin B-12 (mostly in the liver), which can last up to five years in the absence of daily intake, I wouldn’t advise taking that chance. [4]

Are You Vitamin B-12 Sufficient or Deficient?

Despite a healthy and balanced diet, physiological (genetics, disease) and environmental (medications for diabetes, etc.) factors can interfere with normal B-12 absorption for many people, leading to depletion or outright deficiency.

Blood level testing is the surest diagnostic method to assess if you are B-12 deficient. Here is a general guideline to follow to determine whether or not you are vitamin B-12 deficient:

180-914 ng/L Low Range/Normal High
450+ ng/L Healthy/Optimal
180-400 ng/L Conditionally low levels
150-180 ng/L Low levels where disease symptoms start

Depending on test results and potential concurrent symptoms, other simple follow-up blood tests which indirectly test for B-12 status may be suggested, including homocysteine and methylmalonic acid/MMA (levels of these molecules rise when vitamin B-12 deficiency-symptoms unfold, testing of which often allows for a more thorough assessment, in conjunction with B-12 testing).

Symptoms of Vitamin B-12 Deficiency

Below are just some of the overt symptoms of low levels and deficiency of this crucial vitamin.

  • Pernicious anemia
  • Neurological impairments such as depression, confusion, disorientation, schizophrenia, ADHD
  • Memory loss, Alzheimer’s/dementia, Parkinson’s, brain fog, cognitive decline, brain shrinkage
  • Peripheral neuropathy
  • Bowel/urinary tract incontinence
  • Paresthesia (tingling in the limbs)
  • Loss of balance
  • Fatigue
  • Alzheimer’s, dementia, cognitive decline and memory loss
  • Multiple sclerosis (MS) and other neurological disorders
  • Mental illness (depression, anxiety, bipolar disorder, psychosis)
  • Cardiovascular disease
  • Learning or developmental disorders in kids
  • Autism spectrum disorder
  • Autoimmune disease and immune suppression
  • Cancer
  • Male and female infertility

Bottom Line

Considering what we know about vitamin B-12 and its importance for our health, the simplest and least expensive insurance against vitamin B-12 deficiency is supplementation. It’s possible to get enough via diet, but it’s difficult and requires a healthy amount of consistency. A B-12 shot is another solution preferred by many and I don’t have much problem with it except that it can get expensive, be difficult to access regularly, and heaven help you if you’re not a fan of needles. Simply supplementing with an absorbable form of B-12 like methylcobalamin or adenosylcobalamin can really help fill the gaps in easy fashion. I recommend VeganSafe™ B-12, my vegan friendly formula that combines both of these bioactive forms of B-12. VeganSafe B-12 is an excellent supplement that has received amazing reviews.

Is B-12 a big part of your life? Leave a comment below and share your experience!

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Everything You Need to Know About Vitamin B-12

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References (4)
  1. Elizabeth A. Varga, MS; Amy C. Sturm, MS; Caron P. Misita, PharmD; Stephan Moll, MD. Homocysteine and MTHFR Mutations. Circulation. 2005;111: e289-e293. doi: 10.1161/01.CIR.0000165142.37711.E7.
  2. National Institutes of Health. Vitamin B12. NIH Fact Sheet.
  3. Mayo Clinic Medical Labs. Vitamin B12 Testing. Mayo Clinic Fact Sheet.
  4. Harvard Medical School. Vitamin B12 deficiency can be sneaky, harmful. Patrick J. Skerrett.

†Results may vary. Information and statements made are for education purposes and are not intended to replace the advice of your doctor. Global Healing Center does not dispense medical advice, prescribe, or diagnose illness. The views and nutritional advice expressed by Global Healing Center are not intended to be a substitute for conventional medical service. If you have a severe medical condition or health concern, see your physician.

  • Martel

    Thanks for discussing the need for taking B12. In a future article, you may want to discuss the need for those people who have the MTHFR gene mutation to take the active forms of B12 and folate. There may be a connection between the MTHFR gene mutation, Chronic Inflammation Response Syndrome, Chronic Fatigue/Fibromyalgia and the inability for the innate immune system to remove biotoxins from the body. Supplementation with the active forms of B12 and folate, as opposed to the more inactive forms, may be a critical step for people who have the MTHFR genetic mutation to regain their health.

  • That’s a good suggestion, we’ll edit this and add some information about that. You can also check out this article for more info-


  • bilejones

    “the premiere scientific health bodies officially sanctioned by the U.S. government on matters of nutrient intake”

    You do realize that this is instantly a cause of doubt, don’t you?

  • I see your point. Hopefully, B12 is benign enough to cast little suspicion, however

  • Lisa Gough

    I am an affiliate with a company that has a really good sublingual B-12 tablet. It is just as effective as a B-12 shot.

  • Nain

    HI can children take the vegansafe B-12? if so what would be the dosage thanks

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