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A Silent Epidemic with Serious Consequences—What You Need to Know about B12 Deficiency


Published on

Reviewed by Chris Masterjohn, PhD

This tired man rubbing his eyes may be experiencing B12 deficiency.
Fatigue is a common symptom of B12 deficiency.

What do all of these chronic diseases have in common?

  • Alzheimer’s, dementia, cognitive decline, and memory loss (collectively referred to as “aging”)
  • Multiple sclerosis (MS) and other neurological disorders
  • Mental illnesses like depression, anxiety, bipolar disorder, and psychosis
  • Cardiovascular disease
  • Learning or developmental disorders in kids
  • Autism spectrum disorder
  • Autoimmune disease and immune dysregulation
  • Cancer
  • Male and female infertility

Answer: Their signs and symptoms can all be mimicked by a vitamin B12 deficiency.

An Invisible Epidemic

B12 deficiency isn’t a bizarre, mysterious disease. It’s written about in every medical textbook, and its causes and effects are well-established in the scientific literature.

However, the condition is far more common than most healthcare practitioners and the general public realize. Data from a Tufts University study suggests that 40 percent of people between the ages of 26 and 83 have plasma B12 levels in the low normal range—a range at which many experience neurological symptoms. Nine percent had an outright nutrient deficiency, and 16 percent exhibited “near deficiency.” Most surprising to the researchers was the fact that low B12 levels were as common in younger people as they were in the elderly. (1)

That said, this type of deficiency has been estimated to affect about 40 percent of people over 60 years of age. It’s entirely possible that at least some of the symptoms we attribute to “normal” aging—such as memory loss, cognitive decline, and decreased mobility—are at least in part caused by a deficiency.

Why Is It Underdiagnosed?

B12 deficiency is significantly underdiagnosed for two reasons. First, it’s not routinely tested by most physicians. Second, the low end of the laboratory reference range is too low.

This is why most studies underestimate true levels of deficiency. Many deficient people have so-called “normal” levels of B12.

Yet, it is well-established in the scientific literature that people with B12 levels between 200 pg/mL and 350 pg/mL—levels considered “normal” in the U.S.—have clear vitamin deficiency symptoms. (2) Experts who specialize in the diagnosis and treatment of a deficiency, like Sally Pacholok, R.N., and Jeffrey Stuart, D.O., suggest treating all patients that are symptomatic and have B12 levels less than 450 pg/mL. (3) They also recommend treating patients who show normal B12 levels but also have elevated urinary methylmalonic acid (MMA), homocysteine, or holotranscobalamin, which are other markers of a deficiency in vitamin B12.

B12 deficiency can mimic the signs of Alzheimer’s, dementia, multiple sclerosis, and several mental illnesses. Find out what this vitamin does and learn how to treat a deficiency. #B12 #B12deficiency #cognitivedecline

In Japan and Europe, the lower limit for B12 is between 500 and 550 pg/mL. Those levels are associated with psychological and behavioral symptoms, such as:

  • Cognitive decline
  • Dementia
  • Memory loss (4)

Some experts have speculated that the acceptance of higher levels as normal in Japan and the willingness to treat levels considered “normal” in the U.S. explain the low rates of Alzheimer’s and dementia in that country.

What Is Vitamin B12 and Why Do You Need It?

Vitamin B12 works together with folate in the synthesis of DNA and red blood cells. It’s also involved in the production of the myelin sheath around the nerves and the conduction of nerve impulses. You can think of the brain and the nervous system as a big tangle of wires. Myelin is the insulation that protects those wires and helps them to conduct messages.

Severe B12 deficiency in conditions like pernicious anemia (an autoimmune condition where the body destroys intrinsic factor, a protein necessary for the absorption of the vitamin) used to be fatal until scientists figured out death could be prevented by feeding patients raw liver, which contains high amounts of B12. But anemia is the final stage of a deficiency. Long before anemia sets in, deficient patients will experience several other problems, including fatigue, lethargy, weakness, memory loss, and neurological and psychiatric problems.

The Stages of a Deficiency

B12 deficiency occurs in four stages, beginning with declining blood levels of the vitamin (stage I), progressing to low cellular concentrations of the vitamin (stage II), an increased blood level of homocysteine and a decreased rate of DNA synthesis (stage III), and finally, macrocytic anemia (stage IV). (5)

Common B12 Deficiency Symptoms

The signs can look like the symptoms of several other serious disorders, and the neurological effects of low B12 can be especially troubling.

Here are some of the most common vitamin B12 deficiency symptoms:

  • Tingling or numbness in the hands and feet
  • Brain fog, confusion, and memory problems
  • Depression
  • Premature aging
  • Cognitive decline
  • Anemia
  • Weakness
  • Fatigue
  • Reduced appetite and weight loss
  • Constipation
  • Trouble balancing (6)

Children can also show symptoms, including developmental issues and learning disabilities if their B12 levels are too low.

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Why Is It So Common?

The absorption of B12 is complex and involves several steps—any of which can go wrong. Any of the following can cause B12 malabsorption:

  • Intestinal dysbiosis
  • Leaky gut and gut inflammation
  • Atrophic gastritis or hypochlorhydria, or low stomach acid
  • Pernicious anemia
  • Medications, especially proton pump inhibitors (PPIs) and other acid-suppressing drugs
  • Alcohol
  • Exposure to nitrous oxide, during either surgery or recreational use

This explains why a deficiency can occur even in people eating large amounts of B12-containing animal products. In fact, many of my patients that are B12 deficient are following a Paleo diet where they eat meat two or three times daily.

Who Is at Risk for a Deficiency?

In general, the following groups are at greatest risk for a deficiency:

  • Vegetarians and vegans
  • People aged 60 or over
  • People who regularly use PPIs or acid-suppressing drugs
  • People on diabetes drugs like metformin
  • People with Crohn’s disease, ulcerative colitis, celiac, or IBS
  • Women with a history of infertility and miscarriage

Note to Vegetarians and Vegans: B12 Is Found Only in Animal Products

You cannot get B12 from plant-based sources. This vitamin is only found in animal products. That’s why vegetarians and vegans need to know the signs of deficiency—and the steps necessary to fix the problem.

B12 is the only vitamin that contains a trace element (cobalt), which is why it’s called cobalamin. Cobalamin is produced in the gut of animals. It’s the only vitamin we can’t obtain from plants or sunlight. Plants don’t need B12, so they don’t store it.

A common myth among vegetarians and vegans is that it’s possible to get B12 from plant sources like:

  • Fermented soy
  • Spirulina
  • Brewers yeast

However, plant foods said to contain B12 actually contain B12 analogs called cobamides that block the intake of and increase the need for true B12. (7) That explains why studies consistently demonstrate that up to 50 percent of long-term vegetarians and 80 percent of vegans are deficient in B12. (8, 9)

Seaweed is another commonly cited plant source of B12, but this idea is controversial. Research indicates that there may be important differences in dried versus raw purple nori; namely, raw nori may be a good source of B12, while dried nori may not be. One study indicated that the drying process used for seaweed creates B12 analogs, making it a poor source of the vitamin, while animal research suggests that dried nori can correct a B12 deficiency. (10, 11) Seaweed may provide B12, but it’s not clear if those benefits are negated when that seaweed is dried. I recommend caution for that reason.

The Impact of a Deficiency on Children

The effects of B12 deficiency on kids are especially alarming. Studies have shown that kids raised until age six on a vegan diet are still B12 deficient even years after they start eating at least some animal products. In one study, the researchers found an association between a child’s B12 status and their performance on testing measuring:

  • Spatial ability
  • Fluid intelligence
  • Short-term memory

Researchers found that formerly vegan children scored lower than their omnivorous counterparts in each area. (12)

The deficit in fluid intelligence is particularly troubling, the researchers said, because this area impacts a child’s ability to reason, work through complex problems, learn, and engage in abstract thinking. Defects in any of these areas could have long-term consequences for kids.

I recognize that there are many reasons why people choose to eat the way they do, and I respect people’s right to make their own choices. I also know that, like all parents, vegetarians and vegans want the best for their children. This is why it’s absolutely crucial for those that abstain from animal products to understand that there are no plant sources of B12 and that all vegans and most vegetarians should supplement with B12.

This is especially important for vegetarian or vegan children or pregnant women, whose need for B12 is even greater. If you’re not willing to take a dietary supplement, it may be time to think twice about your vegetarian or vegan diet.

How to Treat a Deficiency

One of the greatest tragedies of the B12 epidemic is that diagnosis and treatment are relatively easy and cheap—especially when compared to the treatment patients will need if they’re in a late stage of deficiency. A B12 test can be performed by any laboratory, and it should be covered by insurance. If you don’t have insurance, you can order it yourself from a lab like DirectLabs.com.

As always, adequate treatment depends on the underlying mechanism causing the problem. People with pernicious anemia or inflammatory gut disorders like Crohn’s disease are likely to have impaired absorption for their entire lives and will likely require B12 injections or high-dose oral cobalamin indefinitely. This may also be true for those with a severe deficiency that’s causing neurological symptoms.

Typically in the past, most B12 experts recommended injections over high-dose oral cobalamin for people with pernicious anemia and an advanced deficiency involving neurological symptoms. However, recent studies have suggested that high-dose oral or nasal administration may be as effective as injections for those with B12 malabsorption problems. (13, 14)

Try Supplementing

Cyanocobalamin is the most frequently used form of B12 supplementation in the U.S. But recent evidence suggests that hydroxocobalamin (frequently used in Europe) is superior to cyanocobalamin, and methylcobalamin may be superior to both—especially for neurological disease.

Japanese studies indicate that methylcobalamin is even more effective in treating neurological symptoms and that it may be better absorbed because it bypasses several potential problems in the B12 absorption cycle. (15, 16) On top of that, methylcobalamin provides the body with methyl groups that play a role in various biological processes important to overall health.

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Chris Kresser in kitchen

Change Your Diet

Nourishing your body through whole food is the best way to get the vitamins and nutrients you need. If you’re low on B12, try eating some vitamin-rich foods like:

Eating other kinds of seafood, like octopus, fish eggs, lobster, and crab, can also help you attain normal B12 levels. If you’re seafood-averse, you can also get this vitamin from:

  • Lamb
  • Beef
  • Eggs
  • Cheese

It’s important to note, though, that the amount of B12 in these foods is nowhere near as high as the levels in shellfish and organ meats.

What to Do if You’re Experiencing Vitamin B12 Deficiency Symptoms

If you suspect you have a deficiency, the first step is to get tested. You need an accurate baseline to work from.

If you are B12 deficient, the next step is to identify the mechanism causing the deficiency. You’ll probably need help from a medical practitioner for this part. Once the mechanism is identified, the appropriate form (injection, oral, sublingual, or nasal) of supplementation, the dose, and the length of treatment can be selected.

So, next time you or someone you know is “having a senior moment,” remember: It might not be “just aging.” It could be B12 deficiency.


Join the conversation

  1. Jan,

    Have you been tested for MTHFR? You might be deficient in other B vitamins such as folate. There are prescription forms of methylfolate (the activated form) such as deplin, metanx, and cerefolin. Taking methylfolate in conjuction with the b12 might help your neurological symptoms. You might try googling “MTHFR treatment”, or if you are in the WA state area there is a fantastic doctor named Neil Rawlins that treats B vitamin deficiency and MTHFR. You can even do a google search and find his MTHFR protocol online…

    • I agree with everything Mary Ann says, except for one thing — Rawlins is not a doctor…he’s a patient who went through similar issues related to b12 and methylfolate and MTHFR problems. I’m looking into that myself…after 13 years of worsening CFS.

    • Mooney’s website is remarkable. No doubt, he is a director of a supplement company and recommends his own products. But his depth of research is compelling.

  2. Chris
    I saw my PCP yesterday. He did not seem very concerned with the deficiency. He said that I could do injections or subingual. He had the same results with both. I think that my biggest concern is my advanced neurological symptoms. Perhaps he is not figuring that into the equation. He is an excellent Dr. and said he had some research to do. I have always trusted him without qualms. But he did not really seem to see the need for the B12 type that I was pushing for. I feel that with my level on up to 457 after giving myself injections every day for a week and having done it once a week for two weeks before that level was attained says something about my body still not taking the B12 up properly.

    Bottom line, how long before I would just die if no one took this seriously, or became paralyzed or fell into dementia? I am just worn out with it all. I am tired of dealing with it. I am ready to lay down.

    • Jan, please, take a high-dosage of vitamin-D3. As soon as posible. Even if B12 and folic acid and B6 are important to you, so is vitamin D.

  3. What to do in a borderline case? I just got the result: 465 pg/ml, which is above the 450 minimum of Pacholok and Stewart (cited above), but below the 500 minimum that you referred to in the case of Europe and Japan.
    What is the best option:
    i. eat more liver?
    ii. take a B12 supplement?
    iii. do nothing and test again in a year?


    • This website claims that optimal is above 800:
      “B-12 lab test: Measures an essential vitamin, B12, which can be low in hypothyroid patients due to low stomach acid. You are looking for an optimal B12 lab result at the top of the range. It is NOT optimal to simply be “in range”. If your range is similar to 180-900, a healthy level is 800 or higher. In the 500-800 range, you can benefit from taking B12 lozenges, specifically Methylcobalamin. It has been shown in studies that patients with labs under 350 are likely to have symptoms, which means the deficiency is very serious and has gone on for a few years undetected. Lab ranges are much too low for B12…in Japan the bottom of the range is 500.”

      • There’s really no support for that number in the scientific literature. That said, there’s little risk of toxicity with B12 and little harm that can be done by supplementing with methylcobalamin even if you have normal levels. And in fact, I have some patients that do have levels of 800 or even higher that still benefit from supplementing. Placebo? I’m not sure, but since there’s not much risk I’m not concerned.

  4. Conventional Wisdom says that if you’re over 50…you’re probably B 12 deficient.
    So….I’ve taken a 1,000 mcg lozenge, 4-5X a week for a couple of years now.

    I had a recent blood test and my B 12 level was a bit high.
    It came in at 1165, which is a bit over the upper level of 1000.
    No health issues here other than some reflux issues.
    I’ll be going for another B 12 test in June.
    That’ll also include a complete blood test.
    Until then I’ve stopped taking any more additional B 12.
    Other than what’s in a multi.

    It’s interesting how everyone I speak to on this, hasn’t seen this before.
    High levels can be a sign of serious matters I’m told…but…how high ?
    Can the high level here be due to a daily B 12 supplement ?
    I’m the oddball on this one.
    As “CW” says you can’t take too much B 12.
    Maybe I’m the 1% who can.
    I’ll know more next month I guess.

  5. This is all very confusing and scary to me. I have no idea what kind of Dr. to see. I can remember my tongue losing all the coating on it and turning bright red back to 2000, and no one knew why, as well as the corners of my mouth cracking and being sore. I know now that this could very well have been B12. Now, with my B12 level at 151, and after giving myself shots of cyanocobalamin, 1 ml daily for a week, then once weekly for a mo, it was at 457 after two weekly shots. What does that say to you? I think that it should have been much higher? What should I be doing, what kind of dr? Do I go to a hematologist, still to my MS neurologist, my Primary care, who? I am just now finding you, and this site. I have lost all feeling in my feet and most of it in my hands. I have these large lumps that have arisen on the tops of my feet, that had turned dark brown and the skin was thickened six years ago. These lumps just came now. Why? I lost my legs today, and fell. I am confused, went through a horrible confession from my spouse of almost forty years three yrs ago, and I am angry. If this could have been prevented by the simple intervention of treating my B12 deficiency, and I would have my feet and life, my God. I see the three kinds of B12 and it seems I am taking the wrong kind? Am I spinning my wheels? Am I just going to keep going down, end up dead? What stage am I and how is that determined? Is 151 a really low number? I really do not like liver, but should I be eating that? Where do I turn? I need help desperately. Is my life over at 59.

    • Jan, I think it´s important that you also take folic acid/folate and B6 with your B12, for your MS, you must take vitamine D3, mega-doses.

      • Thank you for replying Elisabeth. It seems that the lumbar ruled out MS. Not 100% because there was protein in the punch but a huge amount. I have a brain tumor in my brain stem, one that the prev. MS doctor told me was gone. On the report it says that it is there, in the midbrain, located near the aquaduct but not clogging it. Well, it may be changing. See when they ordered the punch, I asked them, are you sure since I have this thing on my brain and you are not supposed to do that to someone with that. The brain surgeon said, no, it is ok. Only when there is one that is causing pressure or blocking the flow. Well, he as also saying the place was not a glioma (tumor) but a hamartoma (malformation from birth) and not a problem. Well, he backed off of that when he saw the large amt of protein. He said it is a glioma, that would account for the protein. And, may be it is affecting the flow. My God. This is like being on a horror show of “we said this, but we really meant this” and all your enemies are in the audience laughing their asses off. It does not stop. When I had ischemic colitis in 06, I begged to find out why. That is not a normal colitis. Part of your bowel dies for a reason: clotting disorder, obstruction to the bowel, drug use, etc. I do not use drugs, so we needed to find out. Everyone was like, oh who knows. Ischemic Colitis can be a so so thing or serious. I was in the hospital for ten days, passing nothing but blood for at least two, and 9 inches of my bowel was not rejuvenating. It finally did or I would have had to have it removed. I could have died. I had a serious case of it. This is all tied together. I have been on Prevacid for years, is this why I have B12 def? I have been giving myself injections of betaseron for four years. What has that done? I am just sick over all of this.

    • No. Your life is not over at 59. But you need to find a doctor, or some caregiver, who can explain what’s going on clearly and whom you can trust. Keep shopping around till you find one.

    • Jan: at 151 you really need B12 injections. Preferably with methylcobalamin if you can convince your doctor to use that (tell him/her studies have shown it is the best absorbed form with the lowest toxicity). Yes, 151 is low and you need to take action to bring the level back up. Another option is sublingual methylcobalamin – but I would highly recommend you do this under a health care practitoner’s care. You need to find out WHY your B12 levels are so low. If you have an absorption problem like pernicious anemia, which is not uncommon in the presence of other autoimmune diseases like MS, you will have to be on injections or at the very least high dose sublingual B12 indefinitely. I’d say go visit whichever of the docs you listed that you have the best relationship.

      • Chris, I got back the results of the lumbar punch today from my new neurologist and I do not show that I have MS, as the Dr. she replaced had diagnosed said. To complicate this even more, I was shown on MRI in 2006 to have a lesion on my midbrain that had grown from a previous MRI done in 2004. This is what started the ball rolling. When I had breast cancer in 04 I owned a small investment company. I had to close it but I had felt that I was not on top of my game for some time. To reenter the corp work environment at 51 was daunting to say the least so I had a full neurological work up. There was a problem in the brain stem at that time but they did not report it to me. After working for two years and struggling both mentally and emotionally, a Dr, ordered a MRI and the place had grown a bit and that was when I found out it was even there. It sent me to a brain surgeon at the hosp. where I ended up with this MS clinic that I am still seeing. He felt it had not grown but rather the MRI was slicing thinner. And that it was just showing larger. He saw spots on my brain, sent me to the MS doc. He diagnosed MS with the 261 B12 level in front of him and told me that the brain stem issue was totally gone every year since. Had disappeared altogether.

        Well, it has not. The neurosurgeon thought it was a hamartoma, something that is a malformation from birth, and not a glioma. However, my spinal fluid was full of protein so now he says it is due to this brain stem “glioma”. So, seems like I have a tumor on my brain stem,, worst place ever, and a B12 deficiency. I am seeing my PCP today at 3. What am I? When this started, my tongue would get thick, I could not speak correctly, like I was on drugs, could not spell, word find, emotionally I was broken totally. Could not train for new things and retain them. Yesterday I collapsed totally, and I can hardly walk. I am in intense pain in my legs at night and my entire body hurts. Am I doomed to this thr rest of my life because I was not treated in time? What stage would you think I am in? My red cells seem ok, there has been a problem or two along the way. After my breast cancer surgery, they were way out of whack and taking iron for 6 mos corrected that. They said I lost too much blood. I am giving myself injections. But with the other B12, the least desired one. I am going to take your recommendations to the dr. today. I also feel that there is some liability on behalf of the first Dr. who ignored the B12, and there are other issues with him. There is a reason he is no longer at the clinic. The new dr. recommended that I may want to go to the Mayo Clinic also.

        • One other question, if you are taking/giving yourself injections of B12, whichever kind, daily for a week, then have done it weekly for two weeks and have your blood drawn, knowing that it was 151 or lower when you started (the 151 was in Dec. I started the injections in April) I think that the doctor told me that she would expect to see it abnormally high, like in the thousands, initially instead of 457. Is that correct?

          • Jan, it’s my understanding that different folks respond to b12 injections in different ways — and Chris is right — you need the methylcobalamin, preferrably without preservatives. You can get this at compounding pharmacies, but need a prescription from a doctor.

            I just read a study where a 67 year old woman with ‘white matter’ showing up on her MRI’s had complete resolution of her symptoms with high-dose b12.

            Google “B12 deficiency is commonly misdiagnosed” and you’ll pull up lots of information and hope.

            Best regards,


            • I would also try to get a second or third or fourth opinion. Clearly the injections aren’t given frequently enough, and again, aren’t the right form of b12.

              • Hi all,

                Well, there have been developments since I last posted. My Methyl whatever is fine, I have been tested for everything that has been discussed on here. I have not taken too many or much prevacid, I had an endoscopic and colonoscopic exam with biopsies, no celiac, chrons, cancer etc. We are leaving no stones unturned. My lumbar punch came back with a protein level of 123. I have not had my B12 checked again, I am doing that again tomorrow, and I am on once a week again, plus I am going to do a 24 hour check for heavy metal poisoning. I am not as concerned about the form of B12, I am concerned with my levels getting at least to 500 and not stopping progression. So, herein lies the new information.

                The brain surgeon that I saw in 2006 and who did not seem concerned with the brain stem tumor, but preferred to consider it a hammertoma, a thing more like a collection of surrounding matter and not a growing entity, had to step back with the high protein and is now sayng it is a pilotic astrocytoma. However, this is a pediatric tumor and rarely in younger adults and is cured by removal. It is slow growing but gets large. Mine, being in the stem, mid brain area, would not be a great candidate for removal, but should have been watched more carefully if it is what he is now saying and I have been lucky. I am going to Duke for a second opinion. He said he would see me every 18 mos.

                Tomorrow I see a new Dr.,, a neuropathic Dr. to be assessed for CIDP. The high protein in my punch, along with the advancing numbness and neuropathy, it is halfway up my calves, and my hands that have been more like tuning forks are now becoming numb, I am getting scared. Yes, I have a B12 issue but I have much more. It makes sense. The high dose of prednisone helped me last fall, and that would be correct for CIDP. But., this disease is an autoimmine disease, a much worse case of Guillene Barr, incurable, not likely to cause death but unchecked or treated it can. It causes paralysis so my goal at this moment in time is stop this now. IVIG is the treatment thatI am assuming that they will try??? and then blood change out? I have told all of them, no more dye of any sort will go into my body and this can be brought on by vacinations. I was told by the MS doc to get each and every one that you can think of, all flu, shingles, any thing you can think of.

                Scared??? hell yes. The whole game has changed. When my b12 is checked tomorrow I will post what it is.


                • Jan – your story is heartbreaking, though I did not read every entry. I’ve been in a similar situation… lost everything… figured out my own problem after no help from 30 doctors in 5 years. The thing you have to stop doing is seeing mainstream, Western, allopathic doctors. I don’t care how “expert” or famous they are… the more elite, sometime is not a good thing. You want to look for a good integrative medicine doctor, or environmental medicine doctor http://www.aaem.com, or even a naturopath. A holilstic approach is the only way to thrive with or overcome these chronic illnesses… not looking at it like a disease, as a singular deficiency (there’s more to MS than just B12 for sure), and especially as a drug deficiency. My neurologist thought I had CIDP and didn’t offer me any hope. I probably did have it, but a label didn’t tell me WHY I had it or how to get rid of it. Prednisone would have been horrible for me (as it is for most people and only covers up symptoms at best), as I found I was suffering from toxic mold poisoning, which does demyelinate (and yes does cause MS and CIDP and numerous other things). Keep looking for a deeper cause, but find a GOOD doctor from recommendations… be willing to travel. I was driven 11 hours to the doc I found online, when I was too weak and neurologically impaired to drive, or to even stay awake during the drive. And you are right… do NOT get any more vaccines! And keep your spirits high, as that can be more healing than any drug and sometimes nutrients (sounds nuts to some, but there are biological reasons behind how our thoughts cause illness and how our mental state can help to cure disease). Remember our bodies want to heal… we have to remove the barriers, not add more barriers (like vaccines, drugs, negative thoughts, stress). Best of luck to you!

      • Chris,
        I know that we get a lot of folks here with a lot of varying issues and complications, each different in it’s way. I get confused by recommendations and know that I need the guidance of my neurologist and I feel fortunate to have one that is on board. I do not have pernacious anemia, all the concerns with different blood issues that would affect my abilty to absorb B12 have been assessed from taking prevacid too long to my small intestine issues (had colonoscopy and endoscopy with biospsies). I was tested for the issues for MTHR, I mean she has left no stone unturned. But, when administered B12 shots and my levels reached 1513 and it was not stopping the progression of the symptoms, I did not expect it to correct them right off, she knew more was at play. I have no reflexes, ringing in my ears, blurry vision, exceptionally bad ataxia, just so many nasty symptoms. I do not have MS, my spins is free from any sclerosis, but my nerve conduction, and muscle conduction indicate an issue. If there were no brain tumor when they did the lumbar punch and found the high protein, I would be being treated for CIDP, I feel certain. The brain stem tumor in my mid brain has just complicated everything and truthfully I am so sick, I just feel like giving up. Sitting around waiting for the special blood work that the neuropathic doctor is doing I am so disheartened. I hope so much for the B12 to be it. As to why I am not uptaking B12? I wonder if anyone will care. Sometimes I feel like I am just sitting around waiting to die. I did make an appt fir a second opin on the brain tumor. But I do not want the records from the first dr. reviewed. How is that an impartial disgnosis? I just want to start treatment and get better or just have them all leave me alone and let me succumb. I am pretty depressed.

          • Jan,

            I would strongly recommend you get tested for gluten intolerance. This is an insidious condition which masquerades as over 300 symptoms and medical conditions. Google it, because there’s far more to it than I can say here. I have to say though, that gluten intolerance tests are notoriously unreliable. A small intestinal biospy might show a negative result, but if the damage in your gut is patchy, it could easily be missed. Gluten is making us all sick but sadly it will take decades before enough people recognise it. I noly discovered that I am gluten intolerant in my late 50s and have a stack of medical conditions I need never have had to suffer from if only I’d known about GI. I’m not sure if links are allowed in here, but hopefully the ones I’m putting in will be.



            Very best wishes

      • Dr. Kresser;

        I was told about 4 months ago I had a severe B12 deficiency and was give a prescription to start B12 injections right away. My diagnosis so far is thrombocytopenia and will get retested in a few weeks and results soon to follow. What do they mean by nerological and mental problems due to the B12 deficiency? Also, I have been having pain in my right leg just below the knee and it feels like bone pain and my veins are popping more frequently… can this be related to thrombocytopenia?

        • B12/folate deficiency is a potential cause of thrombocytopenia, but also of neurological and cognitive problems because of the role B12 plays in the central nervous system. Yes, your leg symptoms sound like they may be related.

  6. I, unfortuately, am a prime example of a person who has been a victim of B12 misdiagnosis. I was diagnosed with MS and the Dr. had a level in front of him for me of 261. The next year, the level shows at 232, for some reason, there is not a reading for the next year, but Dec of 2010, which is the fourth one, my level had dropped to 151, and a new Dr. replaced the orig Dr. at the clinic I attend. She immed. caught this. By this time, I have lost all feeling in my feet and hands, all of my reflexes are gone, knees, elbows etc, my cognitive processes, awful and intimate life is shot. I lost my career as a finan. planner, my life may very well be forever changed as this. I gave myself B12 injects every day for one week, once a week now for a mo, and will go to monthly I assume for life. My symptoms, thus far, have gotten worse. I am in immense pain. I understand it may be 3-6 mos before I will know if this will turn around my symptoms, but I do not have a good feeling. I have severe gastro issues, have been hospitalized twice during this dance passing blood. It is like no one talked to anyone else. They are doing a full work up with a colonoscopy and endocopy in two weeks, but damn it all, I begged to find out why I was stricken with ischemic colitis suddenly at 54. No one cared. I never knew about the B12. Even though the Dr who left was testing me for it, when I got copies of my blood, it was on a seperate form and not provided, but with our system showing normal ranges of 200-900, it would not have raised a flag. That needs to be changed. I am just lost now. I am 59, lost all my securities licenses, am awaiting the results of a lumbar punch to rule out MS totally, and see what my job’s disability insurance will do. I am set to lose everything.

    • Jan – Have yourself checked for gluten-intolerance. Better yet, go on a gluten-free diet. All of my malabsorption issues stemmed, IMHO, from gluten ruining my gut. I’m still dealing with some neuropathy, memory problems & muscle spasms but they are clearing up after only 3 months on B12 shots. BTW, I’m injecting cyanocobalamin since methyl is hugely expensive, 500mcg every other day. I ordered the syringes & B12 off the web. I don’t care what my blood tests show now since I’ve gotten a lot better in 3 months. Sometimes, though it seems like I’m regressing, then a spurt of progress. Don’t lose hope. Recovery isn’t in a straight line, it’s a jagged line.

  7. B12 shots are among the most popular biomedical treatment for autism. Another thing to consider is gene polymorphisms such as MTHFR that affect B vitamin metabolism. People with MTHFR have to supplement with activated forms of B6, B12, and folate (not folic acid). Most people with the diseases you listed at the top have MTHFR.

  8. When do you trial and introduction of safe starches for someone on the GAPS diet. Would you just have them on it for a few weeks then introduce it? Also, would it be a good idea to start out with the less dense starches (calories wise) such as yucca, rutabagas, parsnips, etc, for a while before trying the denser starches like yams or white rice?

    • And wouldnt it be harder to set up the proper flora levels in the gut including starch in the diet ( I thought that is why she cuts it out)? Or do you only include starch after a certain amount of time has passed and you believe that the flora levels have normalised and some gut healing has taken place? Also, are rutabagas GAPS legal, I know turnips are.

  9. Great post!
    My Mom, now 78, was low (very low) on B12 two years ago. It was diagnosed via lab test, but the doctor did not thought B12 would be of much importance. He was only interested in the cholesterol levels (LDL o. k., HDL triple of normal) and put her on statins, like many years before. For luck there is the internet and I just looked up all lab results and became aware of the low B12 level. My mom took same information to the doc and he informed himself and she got treated by a row of vitamin shots. The difference they made is almost not to believe. My mom was depressive and sick in many ways and the change started only after a few shots. No she is active, interested in live, started sports and having fun again. By the way, she dumped the statins.

  10. Chris, would you suppose a serum B12 level of ~300 *could* cause deficiency symptoms?

    Your blog = great stuff, per usual!

  11. Hi, I have an immunologist who uses Metanx for B12, B6, and folate. She has been using it for years with good results. It is supposed to provide the vitamins in their more active forms. Not sure about it’s effectiveness, as I didn’t have my B-12 levels tested, but my homocysteine levels have always been fine. Hope this can help someone and that it’s a good product.

  12. The methyl trasnfer issue is a large one and you have touched on it here a bit. I think your may have also failed to mention to adequately close the B12 gap it requires high levels of vitamin C as a cofactor in many of the reactions. High enough that oral Vitamin C often does not cut it. Somehow I think you know it but once you go back and look at the pathways biochemically it becomes a real rate limiting cofactor in the real folate issue.

  13. I am confused — if there are no vegetarian sources of B12 and methylcobalamin is a naturally occurring source of vitamin B12, how can it be Vegan? I think I have missed something…?

    • You are confused because Chris wasn’t being honest. B12 is produced by bacteria. B12 supplements are manufactured without using animals and is a more reliable source than eating contaminated plant-foods (soil has b12, feces have B12, sewage has B12…).

      Just grab a vegan b12 supplement or eat b12 fortified foods (assuming you don’t have a GI problem), and you’ll be fine.

  14. Unfortunately, methyl and hydroxy cobalamin are hard to find as they are more expensive and manufacturers don’t put them in multis. How can one find out if they have methylation problems?

    • Take the MTHFR gene mutation test if you like! Also, Jigsaw makes a B-complex that was recently improved to include methylated forms of folate and b12 in one place. Chris, do you think someone with the mutation and digestive issues would have trouble absorbing this? I like that it’s all in one place, but I sometimes add a Pure Formulas Methyl B12 Plus sublingual to the mix (has methylated folate and B12 and that’s it). However I don’t like that it has Metafolin, made by Merck, who is now, according to a natural healing blog, trying (via the FDA and a rider in legislation) to get a monopoly on methylated folate and prevent supp co.s from using the term “folate”. There’s a petition out there about it.

  15. Thanks. Just posting on various sites I have numerous people telling me that low carb paleo eating (or GAPS diet eating) causes stomach problems/digestive, food allergies, messes with cortisol, etc. Is there any truth to that or for the most part has it helped those you use it on?

    My problem now is more so sluggish elimination/difficulty going, some food issues (bloat and water retention), etc.

  16. Great post! My wife has B12 deficiency despite the fact that we’ve been eating paleo for one year. We’re not sure what the cause is, but her doctor just said to take a B12 supplement. I’m worried it could be a symptom of a more serious issue.

    • Always good to do that detective work. If she has pernicious anemia, a B12 supplement isn’t going to do a thing (she’d need injections). That’s also why re-testing is so important.

      • What would be useful detective work for people with confirmed B12 deficiency? A Schilling test? A blood test for gluten antibodies?

  17. Hey there Chris!

    Sorry to make this comment here but I figured it would never get seen if I made it in the thyroid-gut article.

    You say to restore gut integrity you put your patients on the GAPS diet. This is not necessarily a low carb diet, but from the food choices and how it is set up it generally turns into a low carb diet for most (probably 100 grams or lower). Would going on the GAPS diet worsen issues in someone with already high cortisol throughout the day? Would you advise fixing the cortisol first, or do you need to fix the gut before you can hope to fix the cortsiol?

    • It’s a bit of chicken and egg, so they need to happen together, but I generally think fixing the gut is the highest priority.

  18. Theoretically, methylcobalamin may participate in the methylation of inorganic mercury released from dental amalgams, thus increasing its absorption in the mucosal & digestive tracts. This effect may vary according to oral pH and bacterial type/count.

    I have dental amalgams and get frontal headaches after a couple of weeks on 2,000mcg sublingual methylcobalamin daily. Coincidence?

    • Hi Peter,

      Are you still taking the methylcobalamin and do they still cause you to have headaches?