Vitamin B12 – The Energy Panacea?

Having spent many hours working in close proximity to a wall of vitamins, I’ve answered a lot of vitamin questions, and given a lot of recommendations. Before I can make a recommendation, I need to ask some questions of my own. My first is almost always, “Why do you want to take a vitamin?” The most common response I’m given is “insurance” – which usually means supplementation in the absence of any symptom or medical need. Running a close second is “I need more energy.” With some digging, the situation usually boils down to a perceived lack of energy compared to some prior period: last week, last year, or a decade ago. While I may identify possible medical issues as a result of these interviews (these are referred to a physician), I’m often faced with a patient with mild and non-specific descriptions of fatigue. And more often than not, they’ve already decided that they’re going to buy a multivitamin supplement. When it comes to boosting the energy levels, they’re often interested in a specific one: Vitamin B12 (cobalamin). So why does vitamin B12, among all the vitamins, have a halo of benefit for fatigue and energy levels? The answer is part science and a whole lot of marketing.

As has been described repeatedly SBM, multivitamins have an impressive aura of benefit and safety that, by and large, hasn’t been substantiated. Beyond the multivitamins, there are dozens of single-ingredient vitamins that contain doses that greatly exceed anything you can pack into a multivitamin, and usually significantly exceed the Reference Daily Intake. While these products may be appropriate for those that actually need a specific supplement (e.g., high dose folic acid, or calcium) they also increase the potential for unanticipated effects, giving a much higher dose than the typical diet can provide.

How the single-agent vitamins are consumed when self-selected by consumers seems to be influenced more by perceptions of efficacy, rather than the underlying scientific evidence. Vitamin C is associated with preventing colds and influenza (though it doesn’t work) and may be shelved alongside the other cold remedies. The B Vitamins are considered to be the “stress” vitamins, based on the perceptions that these vitamins are more rapidly depleted in people who are more “stressed”. Multivitamins like Stresstabs trade on this image. Among the B vitamins, B12 is often held out as as an almost miraculous energy booster. It’s often marketed as a sublingual product – you place it under your tongue, presumably for rapid, extensive absorption. It’s a claim hyped by supplement purveyors like Mercola, with his not-so-subtly-named “B12 Energy Booster” (warning, the video starts immediately):

If you often feel tired, run-down, and lacking in energy, you’re not alone.  Low energy is one of our country’s biggest health complaints.

Some of the top reasons for this are:

  • Refined foods sold in grocery stores are depleted of vital nutrients…
  • Refined foods are loaded with sugar…
  • Refined foods are full of chemicals…
  • Refined foods are overloaded with food colorings; and…
  • Refined foods are loaded with preservatives…

…but it doesn’t stop there, either.

Add the harmful effects of caffeine, pollution, conventional therapies, and the stress most of us experience everyday… and you’ve got yourself a recipe for energy drain.

Well, I’m here to tell you there’s a new way to give yourself extra energy.* Actually, a cutting edge way to feel more energized — without the jitteriness of caffeine.*  More on this in a moment.

Now, of course, powering up with extra energy is just one of B12’s many health benefits*

(The asterix in the ad copy points to Mercola’s Quack Miranda warning)

It goes on and on, espousing the wonders of “microscopic nanodroplets™” and how it’s conveniently packaged “pre-metered, non-aerosol container that easily fits in your purse or pocket.”

Mercola’s is just one example. Searching “B12″ and “energy” brings me 117 million results. If web hits were evidence, this is Cochrane-level persuasive. But let’s take a closer look at the rationale for B12 and the effect of supplementation – will B12 supplements give “extra energy” as Mercola promises?

The Chemical


The history of vitamin discovery is fascinating and the identification of vitamin B12 is no exception. The result of a search for a treatment of pernicious anemia, vitamin B12 was initially thought to be the active ingredient in liver that supported recovery from blood loss. While the true active ingredient was iron, not B12, raw liver or liver “juice” (ugh) was a source of B12 and was the standard treatment for years. The vitamin was eventually isolated, and its molecular structure identified, by the 1950s. It was also identified that B12 is actually a group of very closely related chemicals, the cobalamins. Cyanocobalamin is the form that’s found in supplements and replacements; other forms include hydroxocobalamin and methylcobalamin.

While pernicious anemia is the classic sign of B12 deficiency, the vitamin plays an essential role in multiple pathways and systems, including the nervous system, where severe deficiency can lead to permanent damage. Where there are unexplained neurologic symptoms, such as paresthesias, numbness, or cognitive changes, particularly in the elderly, we might suspect deficiency.

We depend on our diets to provide B12. It’s naturally present in foods of animal origin: liver, clams, beef, and fish are excellent sources. Among manufactured foods, B12 is also fortified into products like cereals. Deficiency is due to one of three causes:  malabsorption, insufficient intake, and other medical conditions:

Pernicious anemia is a consequence of an immune reaction that destroys the stomach’s ability to secrete intrinsic factor, which is essential for most of our B12 absoption. No intrinsic factor = little B12 absorption = pernicious anemia.  Pernicious anemia can develop slowly, over decades – it’s most common in the elderly, and rare in those under 30.

Diet is the next common cause: Vegetarians and vegans that do not consume animal products must take a supplementary source of B12 – as supplements are yeast-derived, vegetarians are generally pretty responsive to advice and the justification for supplementation, which is particularly important in pregnancy. Outside of these groups, dietary deficiency is rare.

Other medical conditions can cause deficiency through a reduction in absorption, all of which may be more prevalent in older adults:

  • gastritis and H. pylori infection
  • intestinal effects and consequences of from gastrointestinal disease, cancer, or HIV
  • reduced gastric acid secretion secondary to drug therapy like proton pump inhibitors
  • other drugs, like the diabetes drug metformin, which can have gastrointestinal effects

Diagnosing deficiency in symptomatic patients includes measurement of serum vitamin B12. Unfortunately the test is somewhat limited in its usefulness, as it measures total, not active B12. Levels don’t correlate well with symptoms. There’s also overlap between what’s considered “normal” and “abnormal”, so deficiency can exist even when levels look “normal”. Different nomograms have been developed to support evaluation and treatment decisions. Where B12 deficiency is obvious, supplementation may be started without extensive investigations.

The Need for Supplementation

Deficiency is never the result of any short-term issue. The usual (non-vegetarian) “Western” diet provides 5-7 mcg of B12 per day, which is more than adequate to maintain appropriate levels: the RDA is 2mcg/day (2.6mcg/day in pregnancy). The total body stores are 2-5 milligrams, meaning that deficiency is the result of years of reduced intake – missing a day, a week or a month or more of any B12 consumption would not be expected to result in any clinically meaningful effects in someone with previously normal body stores.

Beyond preventing and treating B12 deficiency, supplements are consumed for a huge array of conditions: From the non-specific protection against “toxins” to infertility, depression, cancer, weight loss, kidney disease, Lyme disease and more.  When it comes to demonstrated efficacy, B12 has only been conclusively established to be effective for preventing or treating B12 deficiency. There is preliminary evidence suggesting that B12 supplementation, in combination with folic acid, and pyridoxine reduces homocysteine levels. However it’s not as clear if lowering homocysteine levels reduces morbidity and mortality, as it may be a marker, rather than a cause, of disease. The evidence continues to evolve, and it’s not yet well established that treating elevated homocysteine levels with supplements is justified. There’s also some evidence to support B12 for reducing the risk of macular degeneration.

What about fatigue? In the deficient, yes, fatigue may be symptom of a B12 deficiency. But in those with normal B12 levels, the limited data on supplementation is not persuasive. The few investigations that have been conducted suggest that supplementing  in the absence of a deficiency has no effect on fatigue.

Replacing B12

Beyond your basic tablets, there are sublingual sprays and wafers, and even intranasal administration. An injectable form of B12 is sometimes used, though oral supplementation is the general recommendation, except in cases of serious deficiency with obvious neurologic symptoms. Oral administration fof cases of malabsorption may sound counterintuitive. While oral absorption is limited, particularly in those with pernicious anemia, oral supplements do correct deficiencies – about 1% is absorbed even in the absence of intrinsic factor and stomach acid. (Oral supplements are typically 1000mcg, meaning at least 10mcg will be absorbed, adequate to meet daily requirements and replace body levels gradually. And despite Mercola’s hype, sublingual versions of B12 are no better than oral forms of the vitamin.

Most typical multivitamins contain 6mcg. This alone provide more than necessary for anyone that can absorb B12. Large doses, particularly oral forms, don’t appear to be harmful, and are well-tolerated. So supplementation as part of multivitamin “insurance”, or as a specific supplement, isn’t likely to harm.


While there is an important role for supplementing with vitamin B12 in some groups, high dose supplements to treat fatigue should be guided by a medical evaluation. For the energy seekers, supplementation in the absence of deficiency offers no benefits. Even in the deficient, B12 supplements won’t offer any sudden “boost” of energy:  replacement and recovery takes time. Anyone concerned about their B12 intake should ensure they’re looking to dietary sources first. And for vegetarians and other at-risk groups, supplementing with B12 may be appropriate and science-based.

Posted in: Herbs & Supplements, Nutrition

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22 thoughts on “Vitamin B12 – The Energy Panacea?

  1. DrRobert says:

    I tried having a similar conversation with a naturalist once. She started telling me how in China they pay their physicians to keep them healthy, and if they get sick then they don’t pay the doctors. She completely tossed the ‘ol germ theory out the window. Her ideas of prevention were less sophisticated than most. She believed a tablespoon of buttermilk each day has kept her family from even having a common cold for over ten years.

    I enjoy your twitter feed, Scott. Keep up the good work!

  2. rbm42 says:

    You know what actually reduces fatigue? Sleep. I’m always amazed at the difference in my physical and mental abilities between getting 8 hours of sleep vs 7. Particularly if, by some miracle, it is 8 hours of uninterrupted sleep. I suspect that most of the people complaining about fatigue and loss of energy could be “cured” by simply going to bed an hour earlier. Hmm, I bet I could make some serious coin selling a homeopathic remedy for fatigue that came with (appropriately woo-ified) instructions to take immediately before going to bed, and never to take after 10 pm.

  3. DrRobert says:

    This website needs a “forums” area. :)

  4. CarolM says:

    Great post. I confess to searching for the great B12 panacea. It started when I was slightly anemic many years ago, and an immigrant Ruissian doctor gave me a good ol’ B12 shot. I wasn’t expecting anything, and hadn’t really felt the effects of anemia anyway. But for the rest of the day I felt *fabulous* like I was on speed. I believe it was not placebo effect, because I went back for another and it had no effect at all.

    So I guess it was merely the difference between mild anemia and normal health. Clearly the sublingual B12 and B-bomb supps I’ve tried since then have not given me the same feeling at all.

  5. Dpeabody says:

    Yeah a forum would be a fantastic idea. I’m sure its been suggested, but in the 2 years I have been reading this blog I haven’t seen it.

  6. Janet Camp says:

    Do you ever simply tell these people that they do not need any supplements? Not that it would do any good, but at least it would be the truth.
    I completely agree with rbm42 that if people are so “fatigued”, they should try getting more sleep–or losing weight in cases of obesity.
    I know two vegans who are very strict. They both use supplemental B12 and are the picture of health. i know another one who eats an egg now and then and is also healthy. Just an anecdote, and I only offer it because this blog often speaks of veganism (and even vegetarianism) as if its adherents are an alien race.

  7. I suspect that a good way to fight fatigue for those w/o medical condition casual it:

    Regular adequate, but not excessive, quality sleep.
    A reasonable amount of regular physical activity to maintain a decent level of metabolism.
    A reasonable, decent, balanced diet.

    Just my speculation, but it seems reasonable.

    On a side note, it took various combinations of doctors 4 decades to finally diagnose my mother’s pernicious anemia. She did require injections or B12, and is still getting them, as her levels are still not high enough to transition to oral supplements.

  8. … a note to my side note: as a critical thinker, I have to acknowledge the possibility that my mother may have not been suffering from pernicious anemia for all of the last 4 decades, and it could be a more recent development despite a symptom history dating back 40+ years, though I do suspect she has been suffering from it to some degree or another for quite some time.

  9. DrRobert says:

    Needing B12 is so last week. These days fatigue is always caused by intestinal candidiasis :)

  10. Jeff says:

    Could adequate protein be a way to fight fatigue?

  11. Quill says:

    @ Dr. Robert: don’t you watch Dr. Oz? If “needing B12 is so last week” then intestinal candidiasis is so yesterday! According to the Oz, fatigue is one of the many things caused by irregular colon flow which lets toxins back up in the body and of course toxins are very, very tiring. ;-)

  12. Lhowes says:

    I am vegeatarian and have been for 35 years.
    I try to get regular exercise and eat well.
    I would love to be able to sleep at night…on average I get about 4 hours. I do not drink alcohol or take in any caffeine,I try to go to bed at the same time and have tried all the remedies for insomnia.
    I constantly feel like I have no energy…where can I get some?

  13. maus says:

    @DrRobert: “I tried having a similar conversation with a naturalist once. She started telling me how in China they pay their physicians to keep them healthy, and if they get sick then they don’t pay the doctors.”

    I smile and nod with those ones, how can you have a serious conversation with someone who lies to your face?

  14. Zetetic says:


    “Needing B12 is so last week. These days fatigue is always caused by intestinal candidiasis”

    And I thought fatigue was caused by “Adrenal Fatigue”!

  15. B12 maybe last week for lots of folks, but it’s a timely article for me. Just a couple weeks ago I was researching taking B12, since I suspect I could be deficient. It’s nice to see confirmation that My google U research lead to around the same conclusion.

    My issue is not exactly fatigue, it is all those stupid little symptoms that could be the thyroid condition, could be perimenopause,could be anxiety or just getting older. Things like feeling cold most of the time (with Raynaud’s), tired even after a good night’s rest, periodic weird itchy or tingling sensations, etc.

    My dad had pernicious anemia and I remember how he would have these memory lapses, words, names, etc. He was the world’s worst trivial pursuit player. Now I find myself getting the same thing, but think…maybe just typical aging or the thyroid issues.

    I’ve read that someone who has autoimmune thyroid disease has a higher risk of pernicious anemia, but when I mention these symptoms to my doctor, she generally wants to attribute them to my thyroid condition and I don’t like to demand particular tests from my doctor. It seems silly to hire someone for their knowledge then tell them what to do. :)

    Regardless, I had a brilliant idea two weeks ago, that I would just supplement for b12, then if my symptoms went away, I’d know I had anemia. BUT my research revealed (as Scott Gavura indicated), with pernicious anemia, you have to take BIG doses, which is going to cost BIG bucks and any B12 you don’t need would get passed. I’d almost literally be pissing away a bunch of money on an untested theory AND the positive effects (if there were any) could be too gradual to detect. Sad to see such a brilliant idea snuffed out by reality.

  16. Scott says:

    Adrenal fatigue? Please. It’s low testosterone!

    @ Lhowes:

    I suggest talking with your doctor. There are specialists in sleep problems who may be able to help.

  17. JPZ says:

    Once again, Mercola’s foolishness has triggered SBM bias – but he is a useful ad homenim target for the entire supplement industry. And oooh, Scott used a chemical structure (which looks a bit off to me – shouldn’t there be a heme structure in there) without actually needing to other than to lend credulity to his argument (oh come on, you know it is true), much like SBM-labelled sCAMers if you think about it (makes it more “sciency”). This post is marginally better than the self-deception in his previous posts because most of his vitriol is directed to Mercola’s foolish comments. Pity he didn’t go into the whole FDA concern about fortification of flours with folate to address birth defects. The FDA was all over the importance of B12 in the diet and how folate fortification would mask pernicious anemia in the population. Especially among the elderly – intrinsic factor thing you know (or perhaps you don’t know). Nah, too much valid science for Scott to consider when he disregards honest facts. SBM bias.

    So, yeah Scott, good job showing that B12 isn’t 5-hour Energy. Now maybe (I hope), you can you can finally get your facts straight about how nutrition works. Whoa, actually, you have no training in that area, you just bitxh about that wall of supplements you were expected to push – yellow snow all around it then. I get that. When McDonald’s started the whole “would you like fries with that” suggestive sell, I was there as a pimple-faced sub-18 employee. I didn’t like it. Maybe knowing that dietary supplements were more important than the profit you brought otherwise has damaged your science setting. I can provide those numbers as well if I expected that you would suddenly start respecting numbers. Actually, I hate the fact that selling the untested crap makes so much money that retailers wouldn’t want to stop. I get that.

    But you really need to get back to Science (Hello Science, this is Scott, he doesn’t believe in you, but I hope you will find a way for you two to meet).

  18. DrRobert says:

    JPZ, sounds like you haven’t left your job at McD’s cash register.

  19. JPZ says:

    @ “Dr”Robert

    Nah, Scott is the poster boy for SBM-bias ignoring science when it doesn’t upset sCAMers or make him feel better. I am just one of those nutrition science PhD types who expect critics of nutrition to get it right. I was laughing so hard at his post that I may have become a bit churlish in my previous response. But, I see you didn’t bother to look up a thing I said, so I will write you off as swallowing the Kool-Aid.

    Ad hominem attack, really? Funny thing is, I tried to identify with Scott’s frustration at having to push supplements he didn’t believe in, much like I didn’t like pushing “would you like fries with that” as a child. My pharmacist friends have expressed similar discontent at having been pushed to push dietary supplements that they do not believe in. But, there is a difference between disliking corporate influence on a pharmacist’s decision, and a pharmacist going off reservation to burn dietary supplements without that thing we call scientific evidence. But still Scott provides me humor every time he tries to bitxh about nutrition without a single clue about what he is saying!

    So, have you developed the fundamental ability to understand evidence? Or are you still drinking the Kool-Aid?

  20. JPZ says:

    Had to mention, this got me laughing again.

  21. JPZ says:

    Yep, once again, Scott can’t handle science.

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