Print Friendly, PDF & Email

Vitamin B12 is part of the Vitamin B complex. It is considered to be a “Painkilling vitamin”. It helps DNA production, cardiovascular support, and energy metabolism. In this post, learn more about Vitamin B12, its functions, causes of deficiencies, as well as foods and other sources so you can better incorporate B12 into your life.

Vitamin B12 is a very important marker to monitor, especially if you haven’t been leading the best lifestyle or you have known chronic health issues.

Introduction to Vitamin B12

Vitamin B12, also referred to as cobalamin, is a water-soluble vitamin (R).

It contributes to the successful synthesis of DNA, the normal functioning of the nervous system, and the production of energy (R).

The liver is the main site of storage of vitamin B12 in the human body (R). Humans can obtain vitamin B from dietary sources, fortified foods, and supplements (RR1R2).

It can take the form of cyano-, hydroxyl, methyl, and deoxy adenosyl-cobalamin (R).

Cyanocobalamin, the most stable and unnatural form of vitamin B12, is most commonly used in supplements and does not have a direct cofactor role in cellular metabolism.

The most biologically significant forms of vitamin B12 are methylcobalamin and coenzyme B12 (5’-deoxy-5’-adenosylcobalamin) (R1 R2).

Vitamin B12 was considered the “Painkilling Vitamin” in some countries as far back as the 1950’s (R).

Vitamin B12 Blood Test Normal Range

The normal range for vitamin B12 is between 200 and 900 nanograms per milliliter (ng/mL).

In this case, however, your lab result may be in the reference range, but not actually be in the optimal range. Vitamin B12 even in the ‘normal’ range can be unhealthy and indicate that certain processes in the body aren’t optimal.

Cobalamin helps break down methylmalonic acid (MMA) (R) and homocysteine – hence, high levels of MMA or homocysteine in the blood may indicate a B12 deficiency. Some studies say this is even a better indicator of B12 status than direct B12 measurement (R).

One study in 94 women found that vitamin B12 levels lower than 250 mg/dL increased risk by 3X the likelihood of having a child with birth defects (R).

If you have not yet tested your vitamin B12 levels, I recommend that you ask your doctor for it. If you already have your blood test results and you’re not sure what to make of them, you need to check out Lab Test Analyzer. It does all the heavy lifting for you. No need to do thousands of hours of research on what to make of your various blood tests.

Health Benefits of Vitamin B12

1) Pain Relief

Methylcobalamin, a form of Vitamin B12, reduces the clinical symptoms in legs such as paresthesia (an abnormal sensation like tingling or pricking), burning pains, and spontaneous pain (R).

In one study, methylcobalamin significantly improved symptoms, such as pain and prickling sensation, in patients with neck pain (R).

Intramuscular cobalamin injection is effective in alleviating low back pain in patients with no nutritional deficiencies (R).

Cobalamin provides effective pain management for mouth ulcers (R).

Methylcobalamin treatment reduces pain symptoms in neuralgia, diabetic neuropathy, and lower back pain (RR1R2).

Methylcobalamin improves neuropathic pain (RR1R2R3).

2) Brain Health

Methylcobalamin (MeCbl) is the most effectively taken form of vitamin B12 in neuronal organelles (R).

Cobalamin may have a role in the prevention of disorders of brain development and mood disorders as well as Alzheimer’s and vascular dementia in the elderly (R).

Supplementation of cobalamin is useful in neuronal regeneration. It also repairs the negative effects of ischemia on neurons (R).

A study on rats with sciatic nerve injuries supports the treatment of peripheral nerve injuries with Cobalamin (R).

B12 also increases the regeneration of axons and promotes neuronal repair (R1R2R3).

3) Sleeping Patterns

Cobalamin treatment improves sleep-wake rhythm disorders in human subjects (RR1).

It may increase the light sensitivity of circadian rhythms due to decreased melatonin levels (R).

It’s not normal to struggle falling asleep and wake up in the morning feeling more tired than when you went to bed. Biohacking Insomnia attacks sleep issues from every angle including limbic system repair, hormone levels, and circadian rhythm retraining.

4) Depression

In a randomized trial performed on patients with depression and low normal cobalamin levels, cobalamin supplementation improved depressive symptoms (R).

Studies have found that prolonged consumption (several weeks to years) may decrease the risk of depression relapse and the onset of clinically significant symptoms in people at risk (R).

5) Anti-inflammatory

Methyl B12 suppresses cytokine production of T lymphocytes in cells and is speculated to do the same in patients with rheumatoid arthritis (R).

6) Skin

Topical cobalamin is a new therapeutic option in atopic dermatitis. It is well-tolerable and has low safety risks for both adults and children (RR1).

7) Pregnancy and Lactation

One randomized clinical trial states that oral cobalamin supplementation with 250 μg/day throughout pregnancy and early lactation elevates maternal, fetal, and breast milk vitamin B12 levels (R).

8) Eye Health

Higher homocysteine and decreased B12 levels have been associated with an increased risk of macular degeneration (R).

One study involved 5,442 women at high risk of cardiovascular disease aged 40 or older, who had been taking B6/B9/B12 for 7 years.

The study found a 34-41% decreased risk of macular degeneration when supplementing with B6/B9/B12 may reduce the risk of macular degeneration (R).


B12 (Cobalamin) leads to production of S-Adenosyl-Methionine SAM, which increases methylation (RR1R2R3R4).

Foods Highest in B12

  • Liver (15X RDI in 3.5oz) (R)
  • Clams (R)
  • Sardines (R)
  • Steak (R)
  • Tuna (R)
  • Nutritional yeast (R)
  • Trout fillet (R)
  • Salmon (R)
  • Eggs (R)

Vitamin B12 Deficiencies

Negative Effects of Deficiency

The long-term consequences of less severe B12 deficiency are not fully known but may include adverse effects on pregnancy, vascular, cognitive, bone and eye health (R).

Methylcobalamin increases nerve conduction, myelin regeneration, neuron regeneration, and inhibiting pain transmission (RR1R2R3).

B12 deficiency in women is associated with infertility and miscarriage (R).

B12 deficiency causes excess homocysteine, which is a proven risk factor for cardiovascular disease (R). Individuals with B12 deficiency have a higher prevalence of cardiovascular risk factors such as heart failure, stroke, and diabetes (R).

Deficiency of B12 inhibits melanin transfer between melanocytes and keratinocytes, which may cause darkening of the skin. 19% of subjects in one clinical trial manifested skin darkening resulting from cobalamin deficiency (RR1).

Vitamin B12 plays an essential role in the production of red blood cells and low red blood cells can indicate a B12 deficiency (R, R). Weakness and fatigue can result if your red blood cells are low since you are not getting enough oxygen to tissues.

Since vitamin B12 is important in producing myelin, a deficiency can cause psychiatric and cognitive problems and pins & needles. In one study with 141 patients, 28% of people who had psychiatric symptoms from B12 deficiency didn’t have any signs of anemia (when it was in the ‘normal range’…see Lab Test Analyzer for optimal ranges) (R).

Low levels of B12 have been linked to depression (R) and Alzheimer’s disease and other types of cognitive impairment (R).

Studies have found that prolonged consumption (several weeks to years) may decrease the risk of depression relapse and the onset of clinically significant symptoms in people at risk (R).

B12 deficiency can cause neuropathy or nerve pain (R), either as a result of a lack of oxygen to the nerves or from myelin destruction.

In this study, every patient treated with B12 had improvement in psychiatric problems (39 of 39). They also improved various blood markers, as well as a 50% decrease in methylmalonic acid and/or homocysteine (R).

In one 7-year-old boy, B12 deficiency from a vegan diet resulted in neurological symptoms (R).

Multiple studies show that B12 deficiency in the elderly can increase the risk of weakness, frailty, and disability, and increase hospital stay (R, RR, R).

With regard to bone health, multiple studies show that B12 deficiency can increase the risk of bone fracture and is associated with lower bone mass (R, R).

In 4 people who didn’t have cognitive symptoms or anemia, a swollen and inflamed tongue with lesions was found to be an early sign of vitamin B12 deficiency (R).

Although rare, vitamin B12 deficiency can cause blurred vision or eye pain. This can occur when an untreated B12 deficiency results in damage to the optic nerve (R).

Susceptible people

About 6% of people in the US aged 60 or older are clinically vitamin B12 deficient, while about 20% have technically “normal” levels (148-221 pmol/L), but are far from optimal (R) (see Lab Test Analyzer for optimal ranges).

Vitamin B12 deficiency increases with age, from about 1 in 20 among people aged 65-74 years to 1 in 10 or even greater among people aged 75 years or greater (R).

People at risk of vitamin B12 deficiency include (R):

  • People on a vegan/vegetarian diet
  • People with anemia
  • Older people
  • People with gastrointestinal disorders, such as Crohn’s disease or celiac disease
  • Those who have had gastrointestinal surgeries

Pregnant women require higher levels of B12 to prevent birth defects (over 300 mg/dL (R)).

Infants born to B12 deficient mothers or receiving deficient amounts of animal-sourced foods are susceptible to deficiency between the ages of 6-12 months (R).

Drugs That Increase Risk of Deficiency

Patients with type 2 diabetes who are prescribed Metformin may be at risk for cobalamin deficiency (R).

Proton pump inhibitors or Histamine 2 receptor blockers (Zantac, Tagamet) may lead to b12 deficiency, as a result of poorer B12 absorption (R R1).

Hormonal birth control (oral contraception and DMPA) usage among female subjects reduced B12 levels (R).


Genes (notably TCN2) related to B12 deficiency are associated with autoimmune gastritis (R).

Buy Vitamin B12 (Cobalamin) Supplement

FDA Compliance

The information on this website has not been evaluated by the Food & Drug Administration or any other medical body. We do not aim to diagnose, treat, cure or prevent any illness or disease. Information is shared for educational purposes only. You must consult your doctor before acting on any content on this website, especially if you are pregnant, nursing, taking medication, or have a medical condition.


1 Star2 Stars3 Stars4 Stars5 Stars (63 votes, average: 4.02 out of 5)

Why did you dislike this article?



  • Mazhar Kamran

    I am diabetic and on insulin humalog mix 50. I am suffering from severe neuropathy pains. I m taking pregabalin 100 mg twice a day + tramadol, can some one may pls adivise to take methylcobalamin with the above combination for relief in pains, as I can’t walk properly. Regards

  • Walter

    Any doctor(s) to recommend in New York?

  • mark t

    Dr Group a Microbiologist has a Formula that is Vegan stable and this B 12 is the Best i have used !!!

  • Ramachandra Vinayak Sakhadeo

    My wife, running 67, had to undergo an operation to stop brain haemorrhage on 1st May 2016. The operation was successful but she has started to suffer from short term memory loss since last four to five months. I searched the net for remedies and came upon Vitamin B-12 tablets 1000 micro grams ( Cyancobalamin ) marketed by Lucky Vitamin USA. We are strict vegetarians, so I ordered a bottle and started giving her the tablets , one per day. I have almost finished giving her the tabs from the second bottle, each bottle containing 100 tabs. Her short term memory loss is not progressing so rapidly but is still going on. So what should I do further ? I have already ordered the third bottle.
    My second question relates to my own condition of being a diabetic ( type 2 ). I am taking one Metformin tablet per day for last 7-8 years. Should I also start on Vitamin B-12 , though my memory is almost unaffected ? I also suffer from slightly high B.P. and take one tablet of Nebicard T every day apart from one tablet of Atorlip 40. I am running 72. My father died from a heart attack when he was 61 but mother lived till 89. She did not die from a heart attack but from general weakness.

  • Q

    Thank you for such a great explanation! I have pernicious anemia on my father’s side, and Alzheimer’s on my mother’s side. My dad has had 2 heart attacks, and my mom’s mother died of complications related to Alzheimer’s, and is losing her memory herself now, quite rapidly. Unfortunately, she will not take any type of supplement, and will only take something with a “brand name”, i.e. prescription medicine. I have Graves’ Disease myself, and am now supplementing with Methyl B12, as I am deficient, as well as using many other helpful supplements. My mom’s symptoms have increased (memory DECREASED) exponentially in the last 4 months, so I am trying to find a way to convince her to supplement with Methyl B12! She won’t go to a doctor, either… sigh. In any case, I’M taking the stuff! 😉

  • Margaret Hawes

    I was on Metformin for 20 years !

    I have a new Dr thankfully. I was so tired all of the time .
    My blood test came back with serious B12 deficiency + very low Potassium.
    He immediately took me off of Metformin.
    I have been havingB12 injections for the last 5 weeks. I have to continue to have them for once a month for next 5 months.

    I must say I am impressed with vitamin B12. My energy levels are thankfully improving . Pottasium slowly increasing too.

    And not having Metformin anymore after taking it for 20 years my sugar levels are stable .

    I thank my lucky stars I now have a goid Doctor

  • B12

    Thank you, I will try Methylcobalamin

  • Brian Fisher

    Thank you! Great info!

  • Firdosh

    Can I take b12 vitamin 2500 every day

  • Raj

    Thank you very much Peter, excellent sharing of information and it’s very easy to understand… unlike much technical information which is extremely difficult to understand for a common man… Regards

  • Peter Rutkiewicz

    My family has had significant experience with Vitamin B12 deficiency and treatment and the state of current medical profession’s knowledge with the B12 vitamin’s role in health. First,. the current levels of B12 sought in the United States of 200-850 ng/L (pg/ml) are wrong. In Japan, the range is 550 pg/ml and above and any reading below 550 is supplemented. The Framingham Study of 23,000 residents over 20 years found B12 deficiencies in 75% of the elderly population over 80 years old. The long term symptoms of B12 deficiency are subtle, gradual and can do permanent damage to the CNS and particularly to the health of the elderly. B12 must be methylated to be usable by the body and the best way to supplement is with methylated B12 taken sublingually (under the tongue) once a day. You cannot overdose on B12,,,there is no upper limit. My own B12 level is double the normal range in the USA with no ill effects. If you are B12 deficient, you will typically be given a shot and perhaps pills. But the reason you are deficient is almost always due to an absorption problem and attempting to get more B12 through diet as cyanocobalamin will be unsuccessful. I suggest using 5000mcg methylcobalamin sublingually to rebuild your B12 reserves and maintain your health during the rebuilding. The liver is capable of storing B12 and its reserves are used up gradually over many years (a decade or more) which is why symptoms of deficiency come on gradually and are often not recognized or a B12 test ordered to check.

    B12 deficiency in the elderly is often attributed by doctors as “old age” and our seniors don’t get treatment. Poor short term memory, forgetfulness and then dementia are gradual symptoms that the elderly experience as deficiency gets worse. B12 is responsible for the collagen laid down in the bones (deficiency causes brittle bones leading to fractures) and for the principle neurotransmitter norepinephrine (deficiency causes mental problems, dementia and eventually CNS damage to the spinal cord which is not reversible). Also, B12 is important for the conversion of homocysteine (from protein digestion and absorption) into products that the body can use to maintain cellular repair. High homocysteine levels that result from B12 deficiency can cause heart attack and stroke…common diseases afflicting the elderly.

    Some families have an uncommon genetic affliction called “familial pernicious anemia” which causes absorption problems with B12 earlier in life (20 and 30’s) and is often discovered as anemia results in blood tests. Doctors are not familiar with this condition because it appears in less then 1 in several thousand patients and a doctor may only meet one patient in their career who presents with this problem. My family of English/Scottish origin has this anomaly and we have seen several of our older members suffer unnecessarily due to misidentification and inadequate treatment. One the symptoms have begun to appear it is a critical juncture to treat adequately to prevent fractures, memory problems, dementia and an ongoing and worsening assault on health as you age. Methylcobalamin is the only adequate treatment for the elderly. Cyanocobalamin shots produce extremely slow recovery rates, further risking the patient’s health for several years because the elderly cannot methylate it quick enough to make use of it. If you supplement, methylcobalamin is the way to go. If you are deficient, you most likely have an absorption problem, Methylcobalamin taken sublingually every day will produce an immediate improvement in symptoms and keep you from becoming a life long patient with worsening health.

  • Leave a Reply

    Your email address will not be published. Required fields are marked *

    This site uses Akismet to reduce spam. Learn how your comment data is processed.