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B12 Deficiency: What Everyone (Especially Vegetarians) Should Know


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Eating seafood—like this platter of lobster, clams, and fish—is an easy way to avoid a vitamin B12 deficiency.
Eating seafood—like lobster, clams, oysters, and fish—is an easy way to avoid a vitamin B12 deficiency.

Are you a dedicated vegetarian or vegan? Perhaps you decided to follow a plant-based diet to improve your health but over time you’ve started to experience troubling symptoms such as brain fog, fatigue, poor memory, and even numbness or tingling in your hands and feet—issues you never had previously. If you can relate, then you may have a vitamin B12 deficiency.

Research indicates that vitamin B12 deficiency is far more prevalent than previously estimated, with at least 40 percent of Americans demonstrating suboptimal levels, and millions more going undiagnosed altogether. The consequences of B12 deficiency are serious and can cause irreversible damage if left untreated.

Read on to learn about the health implications of B12 deficiency and why it is significantly underdiagnosed, the best methods for testing your B12 status, and how to optimize your B12 intake with food and supplements.

What a B12 Deficiency Means for Your Health

Vitamin B12 works with folate to synthesize DNA and red blood cells and assists in the production of myelin, which protects your nerve cells (neurons) and regulates nerve impulse transmission. A deficiency of vitamin B12 can have significant health implications for multiple body systems.

Vitamin B12 deficiency is exceedingly common—especially if you’re following a vegan diet. Find out how to tell if you have a deficiency and learn how eating nutrient-dense foods can help you correct it. #nutrientdeficiency #vegetarian #vegan

The classic association of vitamin B12 deficiency with macrocytic anemia, a condition in which red blood cells are larger than normal due to impaired cell division, speaks to the importance of vitamin B12 for regulating DNA synthesis. However, anemia is but one symptom of B12 deficiency. There are many other B12 deficiency symptoms that occur long before anemia sets in, including:

  • Dementia
  • Cognitive decline
  • Memory loss
  • Brain fog
  • Depression
  • Cardiovascular problems
  • Peripheral neuropathy (numbness, tingling, burning in the hands, legs and feet)
  • Impaired immune function
  • Infertility
  • Developmental and learning disabilities

Unfortunately, many of these symptoms are often mistaken for other health conditions, including Alzheimer’s disease and multiple sclerosis. As a result, B12 deficiency is often missed by physicians in the clinical setting, with serious implications for patients’ long-term health.

If You Have an Undiagnosed Deficiency, You’re Not Alone

B12 deficiency is far more common than most healthcare practitioners and the general public realize. A study from Tufts University found 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 neurological symptoms can occur. Nine percent had an obvious B12 deficiency, and 16 percent exhibited “near deficiency.” (1) Surprisingly, the researchers also discovered that low B12 levels were just as common in young people as in the elderly.

Given the prevalence of B12 deficiency, why aren’t more clinicians and health organizations drawing attention to this serious problem? The answer lies in the fact that B12 deficiency is significantly underdiagnosed. Here’s why it’s frequently missed:

  1. B12 status is not routinely tested by most physicians.
  2. Serum B12, the conventional marker of B12 status, only drops in the later stages of B12 deficiency. Relying on serum B12 testing misses many, if not most, people who have an insufficient B12 intake.
  3. The low end of the laboratory reference range for serum B12 is too low. This is why most studies underestimate the true levels of deficiency.
  4. The standard serum test for B12 measures the total amount of B12 in the blood but does not rule out functional B12 deficiency. (A “functional” deficiency means that B12 levels are too low for optimum health, but symptoms like anemia may not yet be apparent or diagnosable.) (2) The determination of functional B12 deficiency requires other measures that are infrequently used by physicians.
Together, these factors mean that the current standard for B12 testing, serum B12, only picks up a small fraction of people with B12 deficiency. This has serious implications for the neurological, cardiovascular, immune, and reproductive health of people of all ages.

New and Improved Testing Methods for B12

Fortunately, new, more sensitive tests for B12 deficiency are now available, including tests for methylmalonic acid (MMA) and holotranscobalamin II (holo-TC). Studies using these improved methods of B12 assessment reveal much higher levels of deficiency than studies using only serum B12 testing.


MMA is a compound in the body that helps with metabolism, via a vitamin B12-dependent enzyme; if MMA levels are high, it suggests that vitamin B12 is lacking. There are two ways to have MMA measured: in the blood serum and in the urine. (3) Some experts believe that urinary MMA is superior to serum MMA as a biomarker of B12 deficiency because MMA is more concentrated in urine than in the blood. However, elevations in urinary MMA can also be caused by kidney dysfunction. Serum MMA, on the other hand, can be elevated in the presence of small intestinal bacterial overgrowth.

If you decide to undergo MMA testing to determine your B12 level, your current health status matters. I recommend urine MMA if you have SIBO, whereas serum MMA is a better option if you have a history of kidney dysfunction.


B12 is transported around the body by two proteins: transcobalamin II (TCII) and haptocorrin. Eighty percent of B12 is bound to haptocorrin, while only 20 percent is bound to TCII. Holo-TC, the marker that measures TCII, falls almost immediately after B12 intake drops. Serum B12, by comparison, measures total cobalamins (a name for cobalt-containing compounds, like B12). But it measures mostly haptocorrin, and doesn’t decrease until B12 deficiency has been going on for some time.


Homocysteine is an amino acid in the blood. It’s a marker of B12 deficiency when elevated, though not exclusively. Elevated homocysteine can also be caused by folate and vitamin B6 deficiencies. Homocysteine is more sensitive than serum B12; however, if it is high, you will need additional testing to determine whether the cause is B12, folate, or B6 deficiency.

Holo-TC, MMA, and homocysteine are considered measures of functional B12 deficiency because they reflect whether B12 is being appropriately utilized in the body.

Your Best B12 Testing Option

So, which one of these markers is best?

  • Holo-TC is the earliest, most sensitive indicator of B12 deficiency.
  • Urinary MMA and homocysteine typically don’t become elevated until the mid to late stages of B12 deficiency.
  • Serum B12 is the least sensitive indicator and usually doesn’t fall until the final stage of B12 deficiency.

While holo-TC testing is often the best way to catch an early B12 deficiency, it isn’t widely available in the United States (though it is in Europe). Here, we generally rely on a combination of serum/urine MMA, homocysteine, and serum B12 testing.

If you choose to get a serum B12 measurement, you will need to refer to a different range than the one provided by the lab when interpreting your results. Although most labs define deficiency at <200 pg/mL, it is well documented that many people experience signs and symptoms of B12 deficiency at levels between 200 pg/mL and 350 pg/mL. (4) Also, be aware that a high serum B12 does not necessarily rule out a functional B12 deficiency, which is best detected with MMA or holo-TC.

The same is true for homocysteine. The lab range often goes up to 15 nmol/L, but research has shown that a homocysteine level of 10 to 15 nmol/L is a substantial risk factor for heart disease, and that relationship is linear—the higher the homocysteine, the higher the risk. (5)

The Earlier You Notice a Deficiency, the Better

There are four stages of B12 deficiency, and the earlier B12 deficiency is detected in the progression of these stages, the more likely it is that the symptoms can be prevented or reversed.

Stages I and II

During the first two stages of a deficiency, your plasma and cell stores of B12 become depleted, and the concentration of holo-TC is reduced. Holo-TC is the only available marker for assessing the first two stages of B12 depletion. It’s likely that you won’t experience any noticeable symptoms if you’re in stages I or II.

Stage III

This stage of functional B12 deficiency is characterized by elevated homocysteine and urinary MMA concentrations in the blood. Serum homocysteine and serum/urine MMA are the best markers for detecting Stage III deficiency. At this stage, some people will experience mild symptoms like fatigue or brain fog, but others may not notice any signs or symptoms.

Stage IV

If you’re in the fourth stage of a deficiency, you’ll experience clinical signs, such as anemia, fatigue, and brain fog. Serum B12 and other markers of Stage IV deficiency may not decrease until this point. For some Stage IV patients, the cognitive and neurological symptoms are so severe that many believe they have Alzheimer’s or Parkinson’s disease. (6)

As you can see, signs like macrocytic anemia and symptoms like peripheral neuropathy or brain fog do not appear until the final stage of B12 deficiency. Stages I and II of depletion can precede deficiency (Stages III and IV) by months or even years!

To complicate matters further, the physical manifestations of B12 depletion can take years to appear. In the case of neurological symptoms, it may be too late to reverse them by the time the late stage of deficiency has been reached. (This particularly serious for children and young adults whose brains are still developing, as well as any adult at risk for Alzheimer’s or dementia.)

That’s why an early diagnosis of B12 deficiency is crucial.

What Is a Normal B12 Level?

As I mentioned before, the cutoff for serum B12 of 200 to 230 pg/mL, used by most studies and labs, is too low. Other studies suggest that B12 levels greater than 400 pg/mL, double the accepted lower limit of normal, boost the beneficial metabolic effects of B12 and prevent neurological damage.

Importantly, research also indicates that at least one-third of B12 in serum is not cobalamin, the metabolically active form of B12 in humans, but corrinoids, which are not metabolically active. This profound finding means that some people with “normal” serum B12 may actually be deficient because the test is counting metabolically inactive corrinoids as B12.

As a rule of thumb, if your serum B12 level is between 200 and 350 pg/mL, B12 deficiency may be a problem. Just remember that a normal serum B12 does not rule out functional B12 deficiency, which can only be assessed with holo-TC, MMA, and homocysteine.

If You’re a Vegetarian or a Vegan, You Should Be Concerned about B12 Deficiency

Vitamin B12 is found almost exclusively in animal foods. For this reason, vegetarians and vegans are highly prone to B12 deficiency. While early studies showed that vegetarians and vegans had only slightly higher rates of deficiency than omnivores, these studies used relatively insensitive markers, such as serum B12, and less stringent cutoffs for holo-TC, MMA, and homocysteine.

The newer, more sensitive measures of B12 status indicate that the prevalence of B12 deficiency is much higher in vegetarians and vegans than previously believed.

For example, one study that used serum B12 (the less sensitive method) indicated that 7 percent of vegetarians and 52 percent of vegans were B12 deficient, whereas when holo-TC was used, deficiency was detected in 77 percent of the vegetarians and 92 percent of the vegans. (7, 8)

Essentially, conventional B12 testing is missing 70 percent of vegetarians and 40 percent of vegans that are B12 deficient! This is a massive oversight that may have devastating consequences for the long-term health of both vegetarians and vegans.

Interestingly, I have noticed in my clinic that other signs of B12 deficiency, such as elevated mean corpuscular volume (a marker known as MCV), can be obscured in vegetarians and vegans. This occurs because vegetarians and vegans often have iron deficiency and a high folate intake; these factors lower MCV and effectively “cancel out” any increase that B12 deficiency would cause. (9) Calcium deficiency, which is common in vegans, can also lead to B12 deficiency because free calcium is required for the absorption of B12. (10) The possibility of multiple nutritional deficits is just one reason to think twice about following a vegetarian or vegan diet.

Omnivores: You Need to Pay Attention to B12, Too

While rates of B12 deficiency are much higher in vegetarians and vegans than in omnivores, that doesn’t mean it’s rare in omnivores. Approximately one in 20 omnivores is B12 deficient. (11) B12 deficiency is also more common in people with risk factors like:

  • Gut problems that decrease intestinal absorption of B12
  • Past or present use of gastric acid-suppressing medications, metformin, or antibiotics
  • A history of miscarriage and infertility

Vegans: You May Need More Supplementation Than You Think

Proponents of vegan diets promote B12 supplementation as the solution to B12 deficiency. However, supplements do not always solve the problem. In fact, research indicates that even well-educated vegetarians and vegans are not supplementing adequately!

Presumably well-educated vegetarians and vegans at a summer camp in the Netherlands were found to have serum B12 levels less than 200 pmol/L, a level associated with reduced DNA synthesis and other harmful metabolic effects. In another study, vegans taking B12 supplements demonstrated a paltry average level of 192 pmol/L.

Furthermore, the rate of B12 deficiency in vegans who supplemented with B12 was higher than in vegans who didn’t supplement! It is not clear why vegans who supplemented had higher levels of deficiency, but it could be due to the interference of supplemental B12 with active B12 levels. (12) In both of these studies, the subjects were from vegetarian/vegan societies and thus likely to be better educated than the general population. However, this did not prevent them from having a B12 deficiency. (If you need help choosing proper supplements, see the last section of this article for more specifics.)

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Your Kids Need B12 throughout Childhood

Women who consume vegetarian and vegan diets during pregnancy and breastfeeding and families that feed their children vegetarian and vegan diets during infancy and childhood are playing with fire and increasing their children’s risk of serious developmental and health problems.

Vegetarian Moms: You Need to Get Enough B12 during Pregnancy

If you’re pregnant and you have a B12 deficiency, your child could have low B12 throughout infancy and childhood. The longer a mother has been a vegetarian, the higher the likelihood she’ll have low serum and breast milk B12 levels that correlate with a deficiency in her infant. (13, 14, 15)

High homocysteine resulting from low maternal B12 status may promote neural tube defects and congenital heart defects in utero. (16)

The Impact of a Deficiency for Your Child

The prevalence of B12 deficiency is 67 percent in American children, 50 percent in New Zealand children, and 85 percent in Norwegian infants who have followed vegetarian or vegan diets their entire lives. (17) This is extremely concerning, as B12 deficiency can have “extensive, severe, and irreversible” consequences for brain and body development in children. (18)

B12 deficiency impairs fluid intelligence, spatial ability, and short-term memory in children; in fact, vegan children score lower than their omnivorous peers in all of these areas. (19)

B12 deficiency in children leads to:

  • Poor school performance
  • Depression
  • Weakness
  • Fatigue
  • Nerve damage
  • Failure to thrive

Even if a vegan or vegetarian child switches back to a diet that includes animal products, they may not be able to reverse all of the problems that come with low B12. A study of kids raised on a vegan diet found that they were still B12 deficient years after they started eating animal products. (20)

That means compromised B12 status in childhood may have negative consequences that extend well into adulthood. (21, 22)

B12 deficiency also has serious health repercussions for adults. Notably, it raises homocysteine, a risk factor for cardiovascular disease, dementia, and Alzheimer’s disease. (23) Ironically, many vegetarians and vegans choose a plant-based diet to reduce their risk of cardiovascular disease, yet several studies have shown that homocysteine levels are higher in vegetarians than omnivores and higher in vegans than vegetarians. (24) Vegetarians and vegans with low vitamin B12 status are at risk of developing circulatory health problems regardless of their favorable profile of traditional heart disease risk factors. (25)

What to Do If You Think You Have a Deficiency

The first step I recommend is to get a holo-TC and/or urinary MMA test. If either of them is abnormal, you should immediately take steps to increase your B12 levels. There are two ways to do this:

  1. Eat B12-rich foods
  2. Supplement

How to Get More B12 in Your Diet

B12 contains a trace element (cobalt), which is why it’s also called cobalamin. Cobalamin is produced in the gut of animals and is found almost exclusively in animal foods. Some of the best sources of B12 are:

  • Liver
  • Clams
  • Oysters
  • Mussels
  • Fish eggs
  • Octopus
  • Fish
  • Crab and lobster
  • Beef
  • Lamb
  • Cheese
  • Eggs

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

  • Seaweed
  • Fermented soy
  • Spirulina
  • Brewer’s yeast
The truth is, there are almost no vegan sources of vitamin B12.

Nearly all seaweed tested has been revealed to contain vitamin B12 analogs (that is, chemically similar) called cobamides that block the intake of—and increase the need for—true B12. (26) The one exception is a combination of dried purple laver (nori) and wild mushrooms, which were shown in one study to reduce MMA.

Using a Supplement

Cyanocobalamin is the most frequently used form of B12 supplementation in the United States. But recent evidence suggests that hydroxocobalamin is superior to cyanocobalamin, and methylcobalamin may be superior to both—especially for neurological disease. This is because methylcobalamin bypasses several steps in the B12 absorption cycle and, unlike cyanocobalamin, readily crosses the blood-brain barrier. (27, 28) On top of that, methylcobalamin provides the body with methyl groups that play a role in various biological processes critical to overall health.

We now know that the dose of B12 in a supplement needs to be 100 times higher than the RDA of 2.4 micrograms/mL to be effective (this comes to approximately 250 micrograms/day). If you’re deficient, your dose should be even higher, at approximately 500 micrograms/day.

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    • Yes, though I’d pay attention if it were toward the high end of normal, since MMA doesn’t become elevated until Stage III deficiency.

  1. Hey Chris,

    It’s a little bit out of subject, but I’ve heard that yeast contains B vitamins, and so I was wondering if unfiltered beer (or beer on the lees, which contains yeast sediment) has some amount of B vitamins as well ?

    Thanks !
    Fleur de Lys

    • No, as it said above in the article, actual B12 is only created in the stomach of animals.

  2. The Jarrow Methyl B12 appears to not be corn-free. 🙁 I’ve learned the hard way that I need corn-free. And, I prefer to not have the sugar alcohols, either, since I don’t do well with them. I see that it is free of wheat, gluten, soybeans, dairy, egg, fish/shellfish, peanuts/tree nuts, which covers a bit more than I need, except for the corn issue.

    Any thoughts for someone needing corn-free?

    I bought B12 Infusion by Enzymatic Therapy, which is corn-free, but I have not tried it, yet. It contains a sugar alcohol, so I don’t want to try it until my stuffy head clears up.

    • Can you handle a very small amount of lactose? Superior Source makes super tiny instant dissolving sublinguals that are methylcobalamin in a base of lactose and acacia gum (no sweeteners).

      Natural Factors methylcobalamin sublinguals are also corn/gluten/soy/starch free (lactose base/sweetener free)

      • It seems strange, but I cannot even handle a small bit of lactose. It gives me sinus problems, which I battle with constantly. And, I don’t do well with gums. I looked at the Natural Factors and it does have lactose. Thanks for the suggestions, though! 🙂

        • Check out the B12 drops on holisticheal.com. They have methyl, hydroxy and adenosyl types of B12. (I know this is a bit late, but maybe you’re getting follow-up posts by email.)

  3. my rudimentary observations have shown me that vegan/vegetarian women who reproduce are ending up with babies who store extreme amounts of fat and end up on the autism spectrum. could this be due to B12 deficiency? this observation based on at least 10 different women in my community…

  4. Hi Chris,
    Being someone on SCD with gut issues and and a few gut-resections, I cannot take sublingual due to the illegal flavorings. I have recently tried a B12 patch – I’m not sure if these are bogus? if so, what would you recommend?

    thanks, Jenn

    • I can’t tell from the B12 patch website, but I recall they use cyanocobalamin, which is an inferior (inactive) form that must be converted to active forms in the body.

    • Jenn, I don’t know what you are restricted from using sublingually, but I have a bottle of Natural Factors B12 methylcobalamin sublingual 1000 mcg that has no flavors, colors, citric acid, artificial sweeteners, etc.

      The ingredients are:
      lactose (from milk)
      croscarmelose sodium
      magnesium stearate (vegetable grade)

      Note: I think that this brand might also have B12 sublinguals of the same dosages, 1000 and 5000 mcg, that DO have that extra stuff in them, so read the labels carefully if you are thinking of purchasing these.

      I am pleased with it so far, but it’s the only methylcobalamin I’ve ever used and I’ve only just begun to take it, so I have no basis for comparison. I have gotten the feeling from reading various discussions in various forums about B12 deficiency that the Natural Factors methylcobalamin is not very highly regarded (in terms of its perceived potency) by experienced users of B12 supplements (such as Freddd and folks who swear by his B12 replenishment protocol). But it seems to be doing something for me, and I try to avoid all the unnecessary flavors/colors/sweeteners that I can.

  5. Hi, I am currently battling with my Dr for further b12 tests after my bloods came back normal. Many members of my family (ibs sufferers) receive the injection. I have recently realised that my symptoms, ie very listless, snappy, very sore lips, NO memory, tingling hands, are more than likely due to this deficiency. I shall probably direct my Dr to this article in the hope of moving things on a little quicker! I am in 38 yr old omnivor with serious cheese cravings if relevant!

    • Why not just go ahead a get a sublingual methyl B12 bottle and see how you feel after 2-4 wks? My serum B12 was 90 (extreme fatigue, ataxia, neuropathy, etc.) and she only wanted to give me one injection. I had pretty severe neuropathy in the left leg and foot (and mildly in the left arm and hand) and when I went from taking nothing to taking the sublingal cyano B12, it got a bit better over a few months. Then I read Dr. Kresser’s original blog article and switched to methyl B12. Within weeks almost all my neuropathy was gone (except when I accidentally ate gluten it came back; or if I eat too high a carb load or too many nuts). Why wait for your doc to address it if you’re feeling crappy. It’s very hard to overdose.

      • May I ask what does of sub-lingual would be advisable? – I`m considering it myself. I`ve had a cobalamanin injection but the effects seem to wear off fairly quickly.

    • Serum B12 tests are USELESS! B12 is water-soluble, so it’s more accurate to test urine than blood. If you’re not excreting much, then it’s highly likely you’re deficient.

      The one caveat here is, of course, that you could be excreting too much due to malabsorption issues caused by IBD, or other gut disorders.

      • Does anyone know how long one would have to suffer from B-12 deficiency for it to be irreversible? I believe that my dad was B-12 deficient from anti-acid use for heartburn. As far as I know his B-12 levels were never checked.

    • My dr. had me abstain from Vit D and Cerefolin (oral b12) for 2 or 3 weeks prior to re-testing. Her reasoning was that if the body wasn’t properly absorbing and refilling the stores of B12, then the tests would likely to be more accurate. So perhaps skipping supplementation for a couple of weeks prior to retesting would be a better test?

    • There are several labs that let you walk in without a dr.’s order and order your own blood tests. why wait for your dr. to come to his senses while your health deteriorates…check with your local lab.

  6. Very interesting article. About 13 years ago I was originally diagnosed with a blood disorder that required a bone marrow transplant and i was getting blood transfusions bi-weekly. I then decided to seek a second opinion, the second oncologist diagnosed me with anemia and started me on B-12 injections and folio acid. Within a month, my counts were almost perfect. The doctor had no explanation of why I was anemic. To this day, I still take monthly B-12 injections and supplement with folate. It was all very scary. I am thinking of starting sublingual to avoid the shots and having to get a prescription. What’s your thoughts?

  7. The last supplement you mention, TMG (trimethylglycine) – is that found naturally as part of the glycine component of bone broth and therefore less important for the bone broth addicts out here? Thanks!

    • Yes. Always best to get it from food when possible. But for therapeutic cases, some may need to supplement.

  8. Hi Chris,
    The B12 you link to is 5 times the daily dose you are recommending (1000mcg vrs. 5000mcg)

    • Oops, will change that right away. Some people do require the higher dose, but I recommend the 1,000 mcg for general/mild deficiency or maintenance.

      • Oh, crikey – I had already ordered via the link before I saw this. So now I have 5000mgc lozenges. Should I take one per week as the commenter above does? Thanks!

  9. A follow-up to the last question. How does one know if they have adrenal/brain issues?


    • christine — this is a good question! flipped around is this. . . “adrenal/brain” concept. I think I have it!

    • You can and should have adrenal function tested by a saliva sample (4 times spread out throughout the day from 1st rising to bedtime) to test your cortisol levels. Will probably need to go to nathropathic Dr. as regular Dr. won’t worry about poor adrenal function until they’re barely functioning at all. Adrenal burnout is common when there’s prolonged stress and if your adrenals are not functioning properly, then you most likely also have thyroid issues. If this is the case, its important to fix the adrenals so you can resolve the thyroid problem.

  10. Hi Chris- I am interested to find out what you know about Vit B sensitivity and overdose. I have symptoms of Vit B deficiency most of the time but whenever I encounter large amounts of B from a multi-vitamin, vitamin water type source, or B Complex supplement, after one or two doses, I begin getting overdose symptoms (major fatigue). I am also very sensitive to the natural sweetener stevia (flu like symptoms, feels like body is shutting down). I have had my liver enzymes checked and they are functioning fine. I have always been very sensitive to pharmaceuticals also (half life lasts much longer for me). Background: I am a fairly fit female in my 30s- 5’5″, 118 lbs. My body type seems to be a little more naturally acidic and my LDL cholesterol level trends a bit higher. I would love to hear your thoughts…. Thanks!

    • Your reaction to B vitamins is so similar to mine. I’m convinced I’m deficient ( I have ongoing gut issues I’m working on, and I think it’s effected absorption), but even with a natural food based B vitamin I had extreme fatigue and flu symptoms, reacting even after a single dose. When I take the Vit B complex it feels like overdose and herxheimers reaction rather than an allergic reaction–but I can’t be sure? I tried sticking it out for a couple weeks and kept taking it, but finally gave up til I can understand this better. I would love to see Chris respond to this!

    • SB above and Amber below,

      What you mention sounds like what has recently happened to me.

      Before I had come across Chris’ 2 blog postings about B12 or the other specialist websites that go in-depth about B12 replenishment (and thus I didn’t yet know that there are several supplements that should be taken ALONG WITH full-strength methylcobalamin), I had been taking a 1000 mcg tablet of methylcobalamin daily for 2 weeks with no problem, and the first steps of healing were really seeming to take place (in terms of my particular deficiency symptoms), but then I suddenly had a “potassium crash” that put me out of commission for about 36 hours (constant heart palpitations, lasting muscular cramps in my back and neck, feeling totally drained).

      I tried to find out what was happening to me and discovered that this kind of crash was common with methylcobalamin (this potential potassium imbalance, called hypokalemia, is even mentioned on the Wikipedia page for B12 deficiency, which I had actually read before I started taking the B12 supplement, but I had just not paid enough attention to that part). I rested, ate as many foods as I could find in the house that are high in potassium, and stopped taking the B12 until I could obtain the other 3 supplements that are meant to balance everything out.

      • What were the other 3 supps that are meant to balance everything out? And did you eventually stop taking the b-12? Or did you find a supp that has other additives?

    • I just started taking metformin. I only took three 500mg pills for 3 days along with dr. recommended b-complex and fish oil. I have been having a horrible reaction since. My body is so itchy from the inside out. From my head to my stomach and sides. My legs and arms itch so bad as well. Could this reaction be caused from the b vitamins?

      • WHY ON *EARTH* ARE YOU BLAMING THE B12, AND *NOT* the metformin…?!

        Why are you even TAKING metformin…?! Why are you not taking control of your diet, instead of shoving Big Pharma’s poisons down your throat…?! That’s what I did – dump the poison and eat a LCHF – preferably Palaeo – diet. That’s what I did; not only did I lose my diabetes, I lost weight, too, 23 stone (322lb) to be exact.

        The itching is known as ‘pruritus’ and is a side-effect of the poison, NOT the B12.

        Other side-effects include: – anorexia (that’s the proper name for ‘loss of appetite’, it has NOTHING to do with the eating disorder, which should be referred to as ‘anorexia nervosa’), nausea, vomiting, diarrhoea, abdominal pain, taste disturbance, lactic acidosis, decreased B12 absorption, erythema (skin reddening), pruritus (itchiness), and urticaria (hives/nettle rash). Hepatitis has also been reported (list taken from the latest edition of the British National Formulary).

        Frankly, with a list of side-effects like that, I’d not want it within 100 miles of me – that’s why I changed my diet instead – but if you’re happy poisoning yourself, go right ahead…

        I believe that most disease is a response to an incorrect diet (somebody said she had coeliac disease, that’s the very one I use to illustrate my point; if wheat was something we were supposed to be ingesting, then why would ANYONE react to gluten…? I’d extend that to ALL grains).

        Obesity is a reaction to eating an incorrect diet, I’d term it a food intolerance. Eat to your genetic blueprint and you’ll not get fat and, if you ARE fat, eating to your genetic blueprint will make you not fat.

        Wasn’t it Hippocrates who said “All disease begins in the gut”…? That’s what he meant – an incorrect diet causes disease. I’d alter that to read “all disease begins – AND ENDS – in the gut” because the correct diet can heal.

        So step away from the metformin, and go and read Chris’s excellent articles on Palaeo for diabetes. Diet will RID you of your diabetes, Big Pharma’s toxins will not – DON’T CONTROL, CURE…

  11. Hi Chris,

    I know that energy shots, like 5-hr energy and others, are not Paleo but they have been the one vice I can’t seem to shake. They contain a similar amount of caffeine as a large cup of coffee and contain mega-doses of B vitamins (B6, B12, B3, B9). I was just curious on what your thoughts were for these types of drinks from a health perspective for someone in maintenance mode (not trying to lose weight).

    Any input would be greatly appreciated.

    • You might not like my answer. The vitamins in these products are usually the lowest possible quality. Caffeine is individual; if you have adrenal/brain issues, it’s not a good idea. If not, there’s nothing wrong with it.

      • No Adrenal/Brain issues here, but I guess it is time to cut back….

        Thanks for the quick response!

      • Chris

        You’re forgetting about the correlation between caffeine and Mg depletion. I’ve been taking high doses of caffeine for years, and am now suffering from osteomalacia (despite taking 15,000IU D3 for years). Without Mg, your body can’t utilise D.

    • Mega doses? There are hardly any B-vitamins in those things at all.. 30mg of Niacin (B3), that’s nothing. 40mg of B6, that’s nothing. 400mcg of Folic Acid (B9), that’s nothing. Perhaps the biggest joke of them all.. 500mcg of B12 (the worst form of b12 too).. 500mcg of b12 is a joke.

  12. Assume you are aware of Biermers disease where you simply cannot absorb B12 and need regular IV injections….

    • Pernicious anemia is another disease that causes B12 deficiency. But many docs now believe that high-dose, sublingual methyl B12 is equivalent or superior to injections in these cases.

      • I have pernicious anemia, and have been injecting myself for the past four years. As I am only 35 and was told that I will have to do monthly injections for the rest of my life, sublingual b12 sounds like a much better way to go!

        How can the high-dose, sublingual b12 be absorbed by my body if I don’t have the intrinsic factor? Is the b12 absorbed into the bloodstream in the mouth somehow?

        Thanks for your time!

        • Sublingual preparations bypass the stomach so wouldn’t be absorbed via the digestive pathway that requires intrinsic factor. You’ll have to ask your doctor whether sublingual B12 can substitute for injections, but many physicians I work with use it for pernicious anemia cases (and I have also had good success with it).

          • A fixed proportion (1.2%) of ingested B12 is always absorbed by passive diffusion which doesn’t rely on IF. This is insignificant at doses obtained from food but highly significant in case of high dose supplements. I take one 5000 mcg sublingual methylcobalamine lozenge per week which should give me about 60 mcg of B12 per week.

          • Hi Chris,
            Do you recommend an iron supplement with b12 shots or sublinguals? My ferritin is very low at a 5. I’m on my 7th weekly shot of cyanocobalamin and was taking methyl sublingual pills daily and my symptoms just got worse. No one seems to talk about symptoms getting worse or a good treatment plan for b12 deficiency. I’m confused about that. Potassium levels can fall, b12 needs a sufficient amount of folate and iron if you are deficient. All these factors play a role in feeling better. It’s more than just a sublingual pill for some and you just feel better. Do you have any thoughts on how you treat your patients if they are deficient in b12 and anemic? And may have possible gallbladder issues.

      • I have celiacs and have been told that b12 is a common dificiency as well, i see no mention if celiacs herein?

        • Holly

          There’s a VERY simple cure for coeliac disease – simply STOP EATING GRAINS! Coeliac disease is the reason I always cite when people argue that grains are necessary for health – if we could assimilate nutrition from them, then coeliac disease wouldn’t exist! Grains are Neolithic and our bodies simply haven’t had the time to adapt. Grains are deleterious to health whether you’re coeliac or not: – they cause obesity (so do starches too by the way), obesity-related diseases, they’re immunosuppressant, they contain anti-nutrients (enzymes which prevent the assimilation of other nutrients) – they really are empty calories.

          I’ve been eating low-carb/high-fat palaeo for around 6 years (I did it because, at the time, I had a LOT of weight to lose (I was 30 stone (420lb) and type 2 diabetic). Lost 22.5st (315lb) in around 2 years. Now 7.5st (105) and a size 4/6 (0/2).

          You don’t need grains! Wheat gluten is one of those anti-nutrients which prevents the uptake of B12.

          • Hi Sarah,
            I have not been diagnosed w/celiac disease but recently found that although I have B12 in my system, I am deficient in B12 and folic acid in my red blood cells. I am now on 2x/week injections (just did my 3rd injection yesterday, haven’t seen much change yet in energy level, brain fog, cramping in hands, tingling in hands, feet, etc. BUT I am hoping and praying for the best!). When I had my blood drawn, along w/the deficiencies, I was found to have slightly high cholesterol. I have been advised by my doctor to omit grains, primarily gluten, as well as corn and dairy. I am wondering what your thoughts are on the Paleo diet b/c of high cholesterol, esp since you have been doing it for quite some time now.

            Honestly, I am at the end of my rope w/my health (or lack thereof). I have 3 small boys, I have no energy, my fuse is very short, I continue to gain weight, I don’t have energy to exercise except for sporadically…Anyone reading this who can provide me w/specific details on what you feel I should be eating, I greatly appreciate your input! ESPECIALLY when it is scientifically proven or tried and true through multiple experiences of pp w/B12 deficiency!

            • Hello, I just read your comment and was wondering how you know that you have a B12 deficiency in your red blood cells?

              • I have two copies of the MTHFR c677t gene mutation and am benefiting greatly from a supplement called Homocysteine Supreme. In 6 weeks, my homocysteine level dropped from 14 to 10.

      • Hello,

        Last week I was diagnosed with hemochromatosis and severe vitamin b defincecy. Today, I received my second weekly b12 injection and am starting to feel like the brain fog is starting to thin a bit.

        Is it common to be low in b and high in iron?



        • Kathy,
          Please see my comment to Liz above your post and consider getting tested for MTHFR mutation, it is relatively common approximately 45%+ of the population has it.

  13. It’s interesting that vegetarians and vegans (like you, I used to follow these diets myself) think that they’re lowering their risks of heart disease when their deficiencies are actually elevating these risks. It’s surprising (or not surprising?) that in spite of the number of studies that demonstrate the devastating results of a B12 deficient diet, you rarely read or hear about it.

    Do you think that taking a sublingual methylcobalamin supplement is as effective as regularly consuming animal products (all other things being equal, like absorption)? I haven’t found any clear information on this issue.

    • Liz: I’m not sure who you’re addressing here? I am not a vegetarian now, though I was for a short time. At the time, I was experimenting with it for both ethical and health reasons, but I wasn’t doing it to lower my risk for heart disease.

      Sublingual methyl B12 may be equivalent in terms of B12 absorption, but of course it doesn’t have the many other benefits of consuming animal products.

      • Sorry, Chris! I know you’re not a vegetarian today. I should have been more clear: one of the main reasons for following a plant-based diet is for health reasons, when actually there are risks due to deficiencies. We rarely see this issue discussed. Thanks!

        • I’ve never been vegan/vegetarian, because I believe that veganism/fruitarianism are forms of ED; you’re cutting out whole food groups which are ESSENTIAL for optimum health and eating primarily Neolithic foods from which we can derive little – if any – nutrition.

          I used to follow – before I was banned – a FB group called ‘Veganism is the Future’ and some of the ‘facts’ they came up with (e.g. were YOU aware that cucumber was 40% protein? No, neither was I! Must be hiding in all that water… Does that mean water’s a good source then…?).

          What made me want to erupt was when the owner posted a pic of her DOG; the poor mutt looked emaciated (unsurprisingly) had a massive lump on the top of his head, and a nasty, raw, red wound under his left eye. I cannot ABIDE hypocrisy; they bang on about animal cruelty – then they get carnivorous pets and STARVE them! She claimed he was 16, but that long on a diet of plants…?! I cried! The comments sickened me – so many people calling him a “healthy dog” because he had a piece of broccoli in his mouth (obviously something wrong with their eyes)!

          According to his owner, dogs don’t need meat at all, they only need the nutrients FOUND in meat which, apparently, they can assimilate perfectly well from plants (so, by her logic, it’d be perfectly okay to feed a rabbit steak. I blame the lack of B12, cholesterol and fat!).

          So, as my parting shot, I posted a pic of a family of wolves (ironically her favourite animal) having lunch. She banned me for that. Guess it’s too much to be reminded that dogs are wolves…

          I’d like to make 2 comments about the post: –

          1. Whilst iron IS found in plants, non-heme iron is very poorly absorbed, when compared to heme. Also, green leafy veg, oft-touted to be the best source of non-heme iron, is actually no source at all, as it contains the anti-nutrient oxalate which completely prevents the iron being assimilated. Not only that, but it’ll prevent the assimilation of any iron contained in anything with which it’s eaten (so that braised calves’ liver in watercress sauce with a side of kale probably isn’t the best idea…).

          2. Vegans – and veggies to a lesser extent – are very likely to be lacking in vitamin D. Yes, it’s true it’s synthesised from the sun, but cholesterol is required in order to synthesise it – it’s chemical name IS colcalciferol after all – and anyone on a strict vegan diet is VERY unlikely to have much of that.

          I know you recommend Jarrow, but I’ve never found they do much for me at all – if anything, I feel MORE fatigued after taking them – even the 5mg. I’ve switched to NOW and they’re FAR better – AND the lozenges are about a quarter the size! YMMV, of course…

          • wow, okay then. Because you know, all Vegans think that Carnivorous animals should eat plants. -_- I have a cat and i feed him meat. Im Vegan. My cat is not. Im skeptical of plant based diets for Carnivores because Ive heard horror stories. But ive also heard horror stories of humans who were not doing the Vegan diet correctly (b12 supplements being part of that) and getting sick or dieing because they seemed to think that being Vegan meant eating only salad or something. As an aside, perhaps the wounds on the dogs face came from it running into something or some other accidental injury. And as long as the animal was healthy, happy, and had no sicknesses, then its fine. Its not animal abuse, although personally i would give the dog a chance to eat meat and see which one it likes best. i have a cat that, when given the chance, is all over a salad.

            • Although after doing a lot of research, i am considering making my cat vegan. He’s an excellent mouser, hes constantly catching and eating things that are natural for a cat to eat (as opposed to cows, pigs, turkeys etc, things cats would never eat in the wild) and none of that meat is diseased and over-processed and diluted with grains and fillers. He is catching it the way predators are meant to catch things. I think he would be fine on a plant-based diet, if done CORRECTLY. Just something i thought of after that comment that made me sound like im anti-vegan pets. Im not.

              • I am by no means bashing vegetarianism or veganism for humans, but please please do not consider a vegan diet for your cat. Cats are obligate carnivores and cannot survive on a diet that does not contain meat. Interestingly, there is one type of raw cat food on the market that is ground mice. Kind of odd and gross to think about…but much more natural than turkey, beef, etc., I will admit. 🙂

              • Cats are true carnivores, they don’t need grains or starches. If they are eating their natural diet as a wild feline (mountain lion, cougar, bobcat, etc.) or feral feline they would be eating their prey, e.g.: mice, rabbits gophers, prairie dogs, voles, deer, chickens, etc. In doing so they would be eating MEAT and only the vegetables in the digestive tract of their prey. Please don’t try to turn your carnivorous cat into a vegan.

                • I have recently switched my puppy to a vegan diet – and it has seemed to get his epilepsy under control! So please don’t assume that all vegans who feed their dog vegan diets are doing it for their beliefs – I still feed my other dog meat – however something about the meat was contributing to his seizures (vet thinks it was antibiotics in meat).

              • Yikes! Hope those mice have not gotten into poison. Have you asked your vet about cats and vegetarian/vegan?

          • Thank-you for taking the time to write this post. I have also posted on various vegan FB pages and websites… apparently, their unhealthy diet affects their reasoning skills. The scariest is when they put a baby or child on their diet. There’s a reason that the North Koreans are, on average, about 3 inches shorter than South Koreans. None of the 5 longest-living groups of people was vegetarian or vegan.

            • What does a terrible North Korean analogy have to with being vegan or vegetarian?

              North Koreans are shorter than their southern counterparts because they don’t have enough FOOD. The country has been underfed for DECADES, and hundreds of thousands have DIED from lack of food.

              Their southern counterparts were also shorter decades ago as well, but the younger kids are taller because they are getting more FOOD.

              This is true in any country where the economic situation is desperate. Vietnamese immigrants to the US are typically shorter, but many of their kids grow very tall.

              I would suggest you evaluate your own reasoning skils because they are not very good.

              Do some research before posting ignorant comments based on nothing but Bro Science.

  14. Ooops. Looks like the links to the suggested supplements are broken. Looks like you got a little CSS in your HREF, if you know what I mean…

  15. My wife and I were vegetarian for 15 years. She has MS (20yrs). We changed our diet to Paleo Feb ’12 as we didn’t feel either of us was getting the proper nutrition. I must say I feel much better/energized, and my wife’s state is much improved. However, we have implemented other therapies so it’s hard to say the exact effect our diet had to do with her improvement.

  16. Hi Chris – The links in your last paragraph are all dead. Thanks for the great post on B12. I was recently told that I had a B12 deficiency and I would like to purchase the Jarrow Methyl B12. I’ll wait for your links to work so that you get your commission for my purchase.

  17. Hi Chris,

    What do you think about B12 injections? Is there any benefit compared to oral supplementation?

    • Some physicians feel they are superior in the case of neurological problems, but other experts believe the opposite: that high-dose sublingual is a better choice in all cases.

      • Chris,

        When my B12 level was at a severe low 41, I had to do a series of injections to get my level up.
        Unfortunately, permanent nerve damage was done cuz no one found it early enough. But a few years ago I researched other ways if taking prescribed B12 in a nasal spray called Nascobal and taken as directed my level has been stable around 700. So no more injections, it costs more but if you have insurance it helps a little and to me is well worth it. I thought I’d share this with you.

      • What do you consider high dose? And can you include a regimen, for example, should I amp up the dosage for a few months and then titrate back down to 1-3 mg per day?

      • I understand that there is also a nasal spray (this is by prescription) and there are B12 patches (not by prescription).

  18. Hi Chris,

    Interesting stuff. Have you found that people with a functional deficiency sometimes show elevations in serum B12?


    • Thanks for bringing that up! Yes, I have. I’m going to add a bit on that to the article.

      • Great! I look forward to your take. I have developed numbness and tingling in the past 6 months. My reg doctor tested my B12 which came in at 1257 pg/ml, but I wasn’t supplementing. She just brushed it off. It took a functional doc to connect the dots between my gastro issues and my likely malabsorption of B12 despite my high intake of animal foods. I was a vegetarian/vegan for 13 years.. that should have clued my reg doc in! Ah well. I have been supplementing 1000 mcg liquid methyl for 6 days. There is a noticeable difference, but I still have tingling. Hopefully the damage isn’t permanent. Fingers crossed!

        • I have the same exact issue I went to over 20 Doctors and no one would help me.I started researching high b12 and found this site im so thankful for it! Im not crazy…I did find a Functional Dr he seems to understand the problems im having but has not treated me with B12 yet.Today I am very sick brain fog, shortness of breath, Tingling hands and feet, anxiety, depression, ect. I feel im at the end of my rope I found out 5 years ago I had high b12 and every time its tested its the same in the rage of 1200’s I just need help 🙁

          • Sheila, I am no Doctor but this sounds like you have Hypothyroid and adrenal fatigue – worth checking out !

            • I jus saw your response,ive been checked 10 times in the last year and a half for thyroid issues the blood work is always normal T3 T4 antibodies negative the did discover a nodule on each side but my endo said they were non toxic.As far as adrenal gland I took a saliva test it was just slightly off.No one knows whats wrong but since going gluten free I feel 50% better im not healed but I pray im getting there.Thank you for your response.

              • Sheila, you need to have a free T3 & T4 test done & also find a doc who takes your symptoms into diagnosing, like temp. 3 times a day under tonge with an old fashioned thermometer, not a digital one. Just diagnosing only with blood work is not good practicing on doc’s part. If your temp. Is below 98.6 most of the day, you have thyroid issues.
                Check out Dr David Brownstein’s website, he’s phenomenal concerning thyroid & Iodoral supplements that I’ve been on for 2 yrs., it will help your thyroid & other things & you won’t have to get on thyroid meds. In fact lots of people are able to get off their thyroid meds due to Iodoral. I buy it off internet, amazon, Optimox, lucky Vitamins sells it & not expensive.

                • hi i went on to look for Iodoral and it comes up on vitamin sites as iodine is this what it is ? thanks in advance .

                • Yes Iodoral is an iodine supplement. This is NOT the solution for everyone. This is only if you are iodine deficient. Most people in a non third world country consume plenty of iodine through processsed foods. I on the other hand have a problem with absorption of iodine, B-12 and a host of other vitamins & minerals but supplementation doesn’t change what the tests show. I even don’t absorb my thyroid meds correctly so I have lots of T4 but its not free and I don’t convert it to T3 either. So far my doctors are at a loss for what is causing my issues; but they still continue to work on it. I wish you luck.

            • I have had progress perferral neurothapy for 10 it started when i 55. I was a tema kick boxer, dancer and extremely active over the last 15 years I have Hyparthroidism Hyparcalcuim attacking me for 5 years. It it has progressed to past my ankles and I get looked ankles, I have start compounds, and compound pills. That have hight b 12 my circulation shows like a cyle very hot weather and very cold get me. I feel helpless. I wear certain shoes, and I am not diebtic. I just had triple by pass, So now protien is important, and be can be found in certain beans. I eat lot of fish, (can not have what is on Chris’s list of which I love) I nee to find some to help me slow this going up my legs….As I will be in a wheel chair. My mouth feels like it burns, teeth are sensitive all throught the mouth, no root problems, but lot of years that many teeth are caped or permanent bridge. I don’t know if neurothapy can go into gums, but it feels like my teeth are hurting (not a tooth ache, and can not eat probably. That’s whe I tried this site.

              I am a young 68….My brain is very clear. Plus my energy is good, it’s the neuropthy that kills my days, I have to put my feet up, but a compound cream on for this so called pain I have it all electricity going from my toes to almost my chins. I still keep exercising for my heart (as will for the rest of life) but I can’t even be consistent. Which is not a good thing. Well thanks for this time and I hope my mouth is not showing thinning of bones of which comes fro Thyroid (high calcium counts) that distroy so many things bone, diggestion, memory I feel like I am in a catch 22. There are cycles but the are not half has long as they were.

              Help if you know a doctor, or research showing how we get it better to conduct our lifes.
              Much appreciation for reading
              Mj in Charleston SC

          • Sheila, we are like one in the same. After going through all the testing with no explanation for all of the symptoms you described, I researched and had myself tested for MTHFR. I was positive for homozygous C677t and have since then researched more of my genetic mutations finding that I can’t absorb Folic Acid and recycle my B12. Tests always show no deficiencies for B vitamins but my body can’t methylate and put them into use properly. Your story is so similar to so many that I have read about. Have yourself tested. You can even order a kit online through 23 andme.com or ancestry.com. They are about $99 and can be kept private. There is an option where you can access your raw genetic data. There are other sites online that will translate the results to you like Nutrahacker.com, geneticgenie.com, and livewello.com.

      • What is your normal course of action when you see elevated serum B12 and a functional deficiency? I know that you said you were reserving judgment on Spectracell, but my daughter showed a functional deficiency with their micronutrient analysis and an elevated serum B12 with a standard blood test. Observationally, my daughter had the tingling in her extremities and mood changes that could be explained by B12 deficiency. I have just started here on 1000 ug/day sublingual B12. What is your rationale for these seemingly opposing lab results?

      • Hi Chris

        Very interesting article, I only wish I knew about this 8 years ago. My B12 level was 41. I’m now disabled and unable to work. I do the best I can around the house but its hard and tiring.
        I’d like to hear from you about this.

        • Judy,

          you should go onto http://www.phoenixrising.me or http://www.howirecovered.com. there is a man on phoenix rising called freddd who was disabled due to b12 deficiency and has managed to recover something like 95% of his health through using methyl B12. it is NOT too late!!!

          i have been doing his protocol for the last 3 months or so myself and am seeing improvments in my health too, actually saw improvments immediately (i am just badly deficient, but was presenting with neurological symptoms like brain fog, depression and numbness)

          dont give up, you may be able to do some thing to help fix it. it won’t be easy but it is possible.

          i hope that you feel better


    • I wonder if the high serum B12 reflects a high analog level and that would be why the individual is deficient. I guess if a true ‘active B12’ level was done, the person would be found to be deficient in the genuine B12. Interested in this especially as one of my colleague’s husband has a very high B12 level (around 1200 pmol/L, I think).