Warning Symptoms of Vitamin B12 Deficiency and How to Fix It

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Warning Symptoms of Vitamin B12 Deficiency and How to Fix It

Vitamin B12 (also called cobalamin) is a water-soluble vitamin which plays an important role in the production of red blood cells and is required to keep nerve cells healthy.

Vitamin B12 deficiency, also called cobalamin deficiency, is a medical condition of low B12 levels in the blood. According to studies, one in every five adults in the United States suffers from vitamin B12 deficiency. (1)


Vitamin B12 is dubbed the energy vitamin and its shortage can result in an array of health problems, including some potentially very serious conditions.

The average adult should get 2.4 micrograms of vitamin B12 daily. (2) Your body cannot produce vitamin B12 and you must get it from food or supplements. Good food sources of vitamin B12 include dairy products, eggs, fish, meat, and poultry.

Despite being a water-soluble, vitamin B12 gets stored in your liver, kidneys and other body tissues, so vitamin B12 deficiency can go unnoticed for a long time. That is where the danger lies. By the time the condition gets detected, there might be some irreversible damage done already.

Some of the symptoms of vitamin B12 deficiency are fatigue, cognitive problems, and tingling in hands and feet. (8)

In this article, you will find out about the role of vitamin B12 in the body, causes and symptoms of vitamin B12 deficiency, how to treat this vitamin deficiency and how long it takes to fix B12 deficiency.

What is Vitamin B12 (Cobalamin) and What Does it Do?

Vitamin B12 (cobalamin) is an important micronutrient that is essential for DNA synthesis and providing your cells with energy.

The reason why it is so important to correct a vitamin B12 deficiency is that a lack of this vitamin can lead to macrocytic anemia. This type of vitamin-deficiency anemia causes large red blood cells and low hemoglobin.

According to research published in the journal Nutrients, vitamin B12 is usually found in protein in most animal foods. To prevent a vitamin B12 deficiency, your body needs to absorb this vitamin during digestion. You get vitamin B12 from foods such as liver, beef, chicken, eggs and dairy foods. (3)

Vitamin B12 and intrinsic factor are closely linked. Researchers from the University of Rochester say that intrinsic factor is a protein in the lining of the stomach that helps absorb vitamin B12. Sometimes, doctors check for this protein to see if an autoimmune condition is causing inadequate intrinsic factor that is associated with a cobalamin (vitamin B12) deficiency. (4)

If you have been diagnosed with vitamin B12 deficiency anemia, you will no doubt wonder how long it will take to fix a B12 deficiency.


How Long it Takes to Correct Vitamin B12 Deficiency

Bringing levels of vitamin B12 to be within the normal range of between 200 and 900 ng/mL depends on the severity of your B12 deficiency. (5)

To help recover from a vitamin B12 deficiency, doctors will recommend a course of treatment involving oral supplementation or injections.

The journal Blood reports that it should take up to a week for vitamin B12 levels to rise. It is usually possible to completely correct a vitamin B12 deficiency within 6 weeks to 3 months. (6)

However, with the proper B12 supplements, you can start to fix a vitamin B12 deficiency fairly quickly. The journal Annals of Surgery reports that B12 levels start to quickly rise after taking B12 supplements. (7)

Causes of Cobalamin Deficiency (Vitamin B12 Deficiency)

There are a number of reasons for having low B12 levels in your blood. The main reasons for a cobalamin deficiency are connected with inadequate absorption from food, or a diet lacking in vitamin b12.

Let’s look in more detail as the main reasons for showing symptoms of a B12 deficiency.

Diet as a Cause of Vitamin B12 Deficiency

One of the main reasons for developing below normal B12 levels is not getting enough vitamin B12 from your diet.

Doctors from the Mayo Clinic say that vitamin B12 is mainly found in meat, dairy product, and eggs. Eliminating sources of B12 from your diet can result in gradually developing B12 deficiency signs. (9)

Many people who switch to a strict vegan or vegetarian diet are at risk of developing low B12 levels if they don’t supplement their diet with B-group vitamins. (8)

According to the journal Nutrients, nori (edible seaweed) is a good food to help prevent a vitamin B12 (cobalamin) deficiency in people who are vegan. (9)

Impaired Absorption Can Results in Lack of Vitamin B12

Malabsorption could be one reason for showing signs of a vitamin B12 deficiency even if you include meat in your diet.

Inadequate B12 absorption can occur for a number of reasons. For example, low vitamin B12 levels are sometimes seen in persons who have had gastric bypass surgery. Also, digestive problems that are caused by intestinal diseases such as celiac disease, Crohn’s disease, or intestinal bacterial overgrowth can also affect vitamin B12 absorption. (9)

Having a tapeworm infection in your body can cause many symptoms, including having a lack of B12. A tapeworm infection will also make it more difficult to recover from a B12 deficiency.

Also certain prescription drugs can affect your ability to absorb vitamin B12, including anti-ulcer drugs, antacids and Metformin – a drug taken by diabetic patients. (34, 35)


Autoimmune Reaction Can Result in Cobalamin Deficiency

Another reason for needing to address a vitamin B12 (cobalamin) deficiency is if you don’t have enough intrinsic factor to help with digestion.

You need adequate levels of the protein intrinsic factor to help absorb vitamin B12. In some cases, an autoimmune condition can affect intrinsic factor and lead to pernicious anemia. (8)

Symptoms of Vitamin B12 (Cobalamin) Deficiency

It is important to address symptoms of a cobalamin deficiency as it can have serious consequences. Because B12 anemia can become debilitating, doctors warn that a chronic vitamin B12 deficiency can be life-threatening. (10)

The symptoms of vitamin B12 deficiency are often not very specific, so vitamin B12 deficiency can go unnoticed for a long period of time. It is also easily mistaken for other conditions, and therefore remains misdiagnosed.

Fortunately, a B12 deficiency is reversible if you spot the symptoms in time and take steps to fix a lack of vitamin B12.

Fatigue and Extreme Weakness

One of the most common signs that you may lack sufficient levels of vitamin B12 is extreme tiredness.

Fatigue is a common symptom with most types of anemia because a lack of red blood cells results in not enough oxygen feeding your cells.

Doctors from the National Health Service say that a vitamin B12 deficiency anemia caused by B12 malabsorption can cause extreme tiredness. (11)

In some cases, doctors recommend B12 supplementation for people suffering from chronic fatigue or fibromyalgia. (12)

In many cases, correcting a B12 deficiency results is having more energy. However, did you know that there could be other reasons why you feel tired all the time?

Shortness of Breath

The lack of energy caused by cobalamin deficiency anemia will also lead to breathlessness.

Doctors report that low intrinsic factor with a B12 deficiency can cause symptoms such as breathlessness. In one case, these low levels of B12 also resulted in extreme tiredness, hair changes, and hyperpigmentation. (13)

Pale Skin

A deficiency of vitamin B12 will also cause you to have skin that lacks in color or has a yellowish appearance.

One of the important roles of B12 is to help produce red blood cells of the proper size in your body. When there is not enough cobalamin in your body, large blood cells cause megaloblastic anemia. One of the symptoms of B12 deficiency anemia is pale-looking skin. (14, 11)

Swollen Tongue

Not having adequate levels of B12 vitamin can also make your tongue look inflamed, swollen, and feel sore.


This B12 deficiency symptom is called glossitis and occurs in around one-quarter of people with B-vitamin deficiencies. Doctors say that the tongue may have red lesions on it and also develop a burning sensation. The tongue should return to normal when the B12 deficiency is fixed. (15)

In one case, the B12 deficiency was corrected very quickly with one injection of 1,000 μg of vitamin B12. (15)

A vitamin B12 deficiency anemia can also cause other oral symptoms apart from a swollen tongue. Vitamin B12 deficiency symptoms in adults also include mouth ulcers, oral infections, and burning mouth syndrome. (16)

Cognitive impairment

One of the neurological symptoms associated with a deficiency of B12 is problems associated with brain function and memory.

Some scientific studies have shown a connection with B12 deficiency in adults and the early onset of dementia and Parkinson’s disease. Correcting levels of vitamin B12 in people can help to improve symptoms of cognitive impairment if it was caused by B12 deficiency anemia. (17)

In one case, neurological symptoms were the only symptom for one adult who had lower than normal levels of vitamin B12. Before the vitamin B12 deficiency was reversed, the man experienced difficulty walking, lower limb weakness, and general fatigue. (18)

Tingling in Hands and Feet

One way that B12 malabsorption or a lack of vitamin B12 from your diet can affect your nerves is by causing tingling sensations.

One study involving over 2,200 adults found that not enough vitamin B12 affects peripheral nerve function. This can result in tingling in the feet and hands, weakness in the limbs, and even loss of sensation. Fixing levels of B12 quickly with oral supplementation can help to prevent or treat neurological symptoms. (19)

Other studies have shown that a lack of vitamin B12 or folate (vitamin B9) can result in megaloblastic anemia. Tingling, numbness, dizziness, and even seizures were reported as symptomatic of a chronic vitamin B12 deficiency (20)

If you suffer from constant tingling in your arms, hand, or feet, find out what else could be the cause.

Difficulty Maintaining Balance

The neurological impact of poor levels of vitamin B12 can also affect your balance and gait.

Researchers from Germany say that is it important to correct a vitamin B12 deficiency as early as possible. Elderly people who show signs of low B12 often have difficulty keeping their balance. Supplementing the diet with cobalamin (vitamin B12) helps to normalize metabolism in the body and prevent a worsening of neurological conditions. (21)

Vision Problems

A sign that you may need to fix a vitamin B12 deficiency is if you have blurred vision for no apparent reason.


The European Journal of Internal Medicine reports that vision disturbances can be associated with cobalamin deficiencies. Vision impairments are often reversed within a few months with B12 supplementation if a deficiency was the cause. (22)

Changes in Mood

Low levels of vitamin B12 can result in noticeable mood changes such as depression and mood swings.

A review of trials using vitamin B12 supplementation for depression found that fixing the deficiency can help manage depression. While taking vitamin B12 wasn’t a quick-fix for depressive symptoms, long-term supplementation can help manage depression. (23)

Vitamin B12 deficiency in children and adolescents can also affect mood. In some cases, a lack of adequate levels of vitamin B12 may cause psychotic episodes and mood disorders until the deficiency is corrected. (24)

Vitamin B12 Deficiency Treatment

Depending on the severity of the vitamin B12 deficiency, it could take a few weeks to a few months to correct the symptoms. However, oral supplements or injections can help to fix a B12 deficiency.

What are some of the ways to correct a vitamin B12 deficiency quickly?

Diet Rich in Vitamin B12 to Treat Cobalamin Deficiency

Unless intrinsic factor or malabsorption has caused your cobalamin deficiency, you can help to prevent vitamin B12 deficiency anemia with a proper diet.

Dietary sources of vitamin B12

Sometimes, you can help to fix a vitamin B12 deficiency or prevent anemia through diet. Making sure your diet includes foods rich in vitamin B12 will help keep your levels within the normal range.

The recommended daily intake (RDI) for a person over 14 year old is 2.4 micrograms of vitamin B12 daily. (33)

Here are some of the best foods to consume to enjoy a diet rich in vitamin B12:

Liver and kidneys. These types of meat are good to get enough iron in your diet as well as plenty of cobalamin.

A 3-oz. (85 g) serving of lamb’s liver can help boost your vitamin B12 levels. One serving of liver contains 65 mcg of vitamin B12 which is 2700% of your recommended daily vitamin B12 intake. (25)

A similarly sized portion of beef kidney will give you 21 mcg of vitamin B12 which is 875% of your recommended daily intake (RDI) of vitamin B12. (26)

Sardines. Oily fish such as sardines are good to eat to help correct your levels of vitamin B12. One can of sardines contains 8.2 mcg vitamin B-12 which is 341% of your RDI. (27)

Beef. One lean beef steak can provide you with around 11.5 mcg of vitamin B12 which is nearly 480% of your RDI. (28)

Other foods high in vitamin B12 help prevent B12 deficiency anemia due to poor diet. Doctors recommend including foods such as eggs, dairy products, and meat to keep your vitamin B12 levels. (29)

How to get enough vitamin B12 on a vegan diet

If you stick to a strict vegan diet or a vegetarian diet, it can be a challenge to get adequate amounts of vitamin B12.

Some reports indicate that it can take as long as 3 years for a vitamin B12 deficiency symptoms to show up after a person switches to a vegan diet. (8)

Some studies show that over 80% of children who are vegan show signs of a B12 deficiency, and up to 90% of elderly people who are vegans don’t have enough vitamin B12. (30)

Non-animal options of vitamin B12 include nutritional yeast and vitamin B12 fortified products, such as B12 fortified almond milk and cereals, and some breads. One medical study says that dried purple laver (nori) is the most suitable vitamin B12 source presently available for vegetarians. (9)

Supplements to Treat Vitamin B12 Deficiency

Supplements can help to correct a B12 deficiency faster than increasing your dietary intake of vitamins.

Vitamin B12 supplements are usually necessary if malabsorption or digestive problems are the reasons for cobalamin deficiency.

Taking B12 supplements under the direction of your doctor can help to quickly fix a B12 deficiency. The National Institutes of Health reports that taking vitamin B12 is good if you have pernicious anemia, megaloblastic anemia, or absorption problems due to intrinsic factor. (31)

Vitamin B12 is also usually present in many multivitamins.

Vitamin B12 Injections – in Cases of Severe Cobalamin Deficiency

Muscular injections are one type of vitamin B12 treatment if you have a severe deficiency. In critical cases of vitamin B12 deficiency anemia, injections can quickly correct a lack of B12.

However, oral supplements can be just as effective as vitamin B12 injections. Therefore, doctors evaluate the need for using cobalamin injections to correct severe vitamin B12 deficiency anemia on a patient-to-patient basis. (6)

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30 Responses to Warning Symptoms of Vitamin B12 Deficiency and How to Fix It

  1. Grace says:

    Beet root and cabbage (wine color) are also high in B12.

    • Jen M says:

      Plant sources are not a good source of B12. Spirulina and plant sources are not bioavailabile. Spirulina carries analogues and actually can block absorption.

  2. Atell Rohlandt says:

    Thanks for the helpful information and tips. I noticed Grace mentioned vegetable options that are high in B12 and that’s going to be very handy for vegetarians/vegans. I’ve been struggling with a lot of the symptoms listed here and will most definitely look at my B12 consumption.

  3. Betsy Kimble says:

    I have been on thyroid meds since 1994, and had major eye problems from Graves’ Disease- (Only one eye bulged) so they put me on prednisone (sp)in 2007, and my weight went from 118 to 202 in less than 6 months- Plus I had the moon face,multiple chins, went from a size 7 to wearing old mens’ size 44 trousers….it was bloody awful. I also was lethargic, mean spirited & unable to control my temper- I was told that Vitamin B12 would help alleviate those problems- I tried taking supplements and found that they made me anxious, nervous, my arms & hands had the shakes, my pulse raced, and my heartbeat was thumping and put me into panic mode- ( I do not drink beverages with caffeine). When I stopped the steroids in 2010, I lost 50 pounds but am unable to shed the remaining 44 pounds- Can you explain why body rejects B12???

    • Jenny says:

      I don’t think I know the answer Betsy. It might be side effects or interaction with other medication, I’m not sure, but your doctor needs to know about it.

    • Claire A. Wilski says:

      I am not a doctor. I am 67 year old female that tends to be super sensitive to SALICYLATES. Most people and actually most Doctors don’t understand Salicylate Intolerance yet. Look up FOODS CONTAINING SALICYLATES on the internet. Salicylates are in many foods and DRUGS and are cumulative. If you ingest too much of them they can send you over the top and cause some of the symptoms you described. It is totally worth your while to look into this as a possible contributor to what you are experiencing. Salicylates are most likely in the B12 suppliments (or any other drug you take). My Doctor basically has given up on me because I cannot tolerate any drug he has prescribed for me. The Feingold Diet helps people with this kind of problem. Also can look it up on the internet. You have to help yourself by doing a little investigative work. Doctors just don’t have time to step outside the box these days and look further into things for us. Frustrating for sure.

      • Jeannie says:

        I can’t tolerate b12 either and I have the mthfr mutation c667T so why can’t I tolerate the methyl b 12? It’s very frustrating! I get body aches feel very anxious and unwell. I also have hashimoto’s

        • Scott H. Bryant says:


    • susan leonard says:

      you also need to take Pernicious Anemia into account…..my mother had it and my sister has it……it is a very little mentioned disease……
      And the effects of it are awful……i am surprised it is not mentioned here…..but look it up…..because if you did have it…you have frequent B12 injections…..and then all your close female relatives…daughters…granddaughters should be checked every 12 months for it

    • Surya says:

      Try taking the methylcobalamin form of b12..if you are taking cynocobalamin you might see some side effects..

  4. Marilyn says:

    I was diagnosed 7 years ago with a B12 deficiency and later, iron anemia. It took a couple of years before we realized that it is a symptom of a low thyroid. Thyroid hormones are sometimes called the metabolism hormone. When you don’t metabolize the food you eat, you don’t get these necessary vitamins and minerals. I was doing the shots monthly, but my thyroid doctor recommended B-12 dots. They are sub-lingual, meaning that you absorb the vitamin directly into the blood stream, bypassing the stomach. I use 4 a week and my B12 levels never looked better. Plus instead of the up and down of the shot, my levels stay more even. I feel great.

    • M Stillwell says:

      What are B-12 dots ? I have never heard of them. I have taken shots for four consecutive weeks and then have been on over the counter B12 Sublingual tabs for about 4 months blood test and told to stay on them and have recheck in four months.

  5. Sharad Kulkarni says:

    Will someone explain: Does deficiency of B12 play any part in patients with Hepatitis B. How far it important in the treatment of such patients?

  6. E Black says:

    it should be noted that if you have an absorption problem, you may need to get the b12 (and b6) in a methylated form. You may also have a gene mutation called MTHFR, which has several varieties. I recently began taking Thorne Methylguard b vitamin supplement and I can’t begin to tell you how much better I feel. I have a group on Facebook for MTHFR. If you have experienced miscarriage and have a b vitamin deficiency I highly recommend asking your ob to test you for MTHFR

    • Christina says:

      You are actually the first person I’ve seen that has ever mentioned this condition. My ob tested me for it a couple of years ago and I have a what he called a “double whammy” as I apparently inherited it from both sides and have double gene mutation.

  7. Angela says:

    Also, if you have a genetic blood disorder such as MTFR you are unable to properly absorb b vitamins. It’s unknown to many medical professionals and you’re blood work could say you have high b vitamins. It’s just that your body isn’t processing them. It can lead to stroke, high blood pressure, dementia, trouble in conceiving, or going full term. Sometimes you won’t notice anything until later in life.

    • Christina says:

      I’m so glad to see people talking about this condition. My ob tested me for it a couple of years ago and I have a what he called a “double whammy” as I apparently inherited it from both sides and have double gene mutation.

    • Jeannie says:

      Hi Angela, I have the mthfr mutation but I can’t tolerate l methyl folate, nobody has been able to figure it out, have you found anything else out since your 2014 post?

  8. Michelle says:

    I would like to add that I have Crohn’s. As a result have had my ilium removed so therefore do not absorb B12 by eating it. Only fix. B complex shots and we are back on track.

    • Anne chalmers says:

      My sister has the same and gets b 12 shots but my father also has the same and does not get any b12 medication, is it different in men?

  9. Emily says:

    I just started taking a b complex about a week ago and I already feel so much better. I was suffering headaches, fatigue, anxiety, and depression. I still have treatment for my anxiety, but the b complex has just really helped me along!

  10. Phyllis Brueckner says:

    Having gastric bypass or “stomach stapling” can also cause a B12 deficiency, and oral supplements do not help. Monthly injections of the vitamin is the only way to avoid this. One can easily learn the simple technique of doing this at home and even though a prescription is needed, the cost is minimal.

  11. sarah says:

    I had alot of dental surgery over the summer. My experience with the laughing gas was scary. I felt like I was dying and I could not speak, my insides were shaky, and my heart was racing. I was a second away from going unconscious when my dentist noticed my body going limp. He turned off the gas and had me breathe oxygen. My legs did not stop shaking for 20 minutes and I was freezing. It must of scared him too because he refused to work on me again until I had my blood checked. I knew I was anemic, but I found out at the doctor’s office that I had a Vitamin B-12 deficiency. The laughing gas was sucking more out. It is rare, but for some, the laughing gas is not funny, it can be deadly. I am taking B-12 now and trying to consume it in Vegan Protein Shakes an Spirluina. I feel better. Seems to make me happier and look less tired. I finished my dental work and braved it all with numbing shots instead of the gas.

  12. Christina says:

    Not sure if this helps or if anyone is interested but I recently heard about a new oral prescription alternative to the injections called Eligen B12. I recently read that it works even if you don’t have intrinsic factor (so even if you don’t have normal gut absorption), which would mean no more shots. Apparently it came out a month or two ago. Has anyone tried it??

  13. Jayasree Anvekar says:

    Boiled rice and its stock which is pink in color, red millet, and whole grain rice which is red in color, an combination of red pearl onions and molasses are rich source of vitamin B12 and iron for vegetarians.

  14. Prakash Deshmukh says:

    Your digestion system is weak then nothing oral will work, what ever food you eat it will go waste. First improve the digestion system and then only take food even tablet won’t work much. Better to go for shot until your digestion system is improved, monthly one is enough if the level is above 200. increase frequency initially if below 200.

  15. Paula says:

    It seems to be a simple blood test that gets overlooked by G Ps these days. As a District Nursing Sister in the 70’s in UK. I had many older patients on regular Vit B12 injections but you don’t hear much about it any more, especially the over 60’s . It should be one of the annual routine tests.

  16. Eula says:

    I suffer from lack of muscle tone, and energy, also from
    Lose of hair. I get cold very easy, ( very cold I keep gloves in my purse. I live in Florida) this happens even in the summer. I also get pins and needles in my arms and legs. I have a good diet. But have no energy and often no enthusiasm to do anything. I do take medications as I have had many surgery’s. Due to a vascular nacreous. And I get dizzy and blurred vision. I have tried to use the B12 in time release but it seems not to help along with a multi vitamin years ago I used liquid B12 that you put under your tongue. That helped a lot. Where can I find this. Thank you my Dr knows all of this. And has put me on blood pressure meds, as I was suffering from severe shackes in my hands . And was hoping to get the liquid. The Blood pressure meds have helped. The dizziness and shakes . However I still have lose of hair , blurred, vision, cold hands, feet and trouble consintrating. Any help finding the liquid
    Thank you

    • Sylvie Bouldin says:

      I hope this may help you! I have recovered from a zinc deficiency by changing my multivitamin/
      mineral to one that supplies 100% Zinc. I was too exhausted to finish mopping the floor!!! and
      had hair loss and breakage and had lost my sense of smell. Dr. Sylvie had to figure this out
      herself because the doctors are too stupid to do it for us!!! They only get 4-6 hours of nutria
      tional training in med school! They spend most of their time getting educated on all of the
      drugs that CAUSE DEFICIENCIES!!! In my case it was the thirteen years that I was prescribed
      Fentanyl Patches for chronic pain after a botched back surgery. I have been off all narcotics
      for four years. Proton pump inhibitors also cause zinc deficiency. FINALLY, my point is, I
      had an intuitive epiphany that I wasn’t assimilating my nutrients (very expensive supplements!!!) and needed hydrochloric acid and digestive enzymes. I am a beautiful, youth
      ful 68 year old and am now growing my brilliant WHITE hair down to my bellybutton – it is
      thick and luscious. Also, I can smell!!!!!! PS Metformin can cause B12 deficiency!

  17. Karen says:

    Eula – try Global Healing Centre Liquid B12, called VeganesVegan-Safe B12e. I am a vegan on a healing journey and use this though I am based in the UK and get it from a UK based Company that sell their products. I have tendinitis in my wrists and use this plus Nutritional Yeast sprinkled over my food daily. Apart from other natural therapies I believe this is easing the pain a little.

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