Health 101

Book Review

The Enigma of Vitamin B12: Nature's Only Mistake?
by Anthea V. Hayes

By Don Bennett, DAS

The book is a skeptical examination of the conventional narrative surrounding vitamin B12 deficiency. It argues that the pervasive fear of B12 deficiency – especially in plant-based diets like veganism – is rooted in a mix of outdated science, fearmongering, and aggressive marketing tactics rather than solid evidence. The author traces the historical "discovery" of B12, dissects inconsistencies in nutritional science, and critiques how symptoms lists have ballooned to over 100 ailments (from bad breath to psychosis) as a potential marketing ploy. She explores themes of institutional trust, corporate profit motives in supplements and food fortification, and propaganda techniques inspired by figures like Edward Bernays, positioning B12 supplementation as "cyanide snake oil" derived from unappealing sources. The book veers into conspiratorial territory by questioning if B12 even qualifies as a true vitamin.

But the author’s assessment that fear of B12 deficiency, particularly in plant-based diets like veganism, stems from outdated science, fearmongering, and aggressive marketing rather than solid evidence doesn't hold up. Is the fear of B12 deficiency rooted in outdated science? I partially agree, but with some caveats. The science of vitamin B12 (cobalamin) is well-established in some respects: It’s essential for neurological function, DNA synthesis, and red blood cell production, and its deficiency can lead to serious conditions like megaloblastic anemia and neurological damage. These findings date back to the mid-20th century and are not in dispute by those who can apply critical, rational thinking to the issue. However, Hayes may have a point about outdated aspects of B12 science, particularly how deficiency is diagnosed and quantified. For instance, early studies set reference ranges for serum B12 levels that some researchers argue are too broad (200-900 pg/mL), potentially overdiagnosing deficiency in asymptomatic individuals or underdiagnosing it in others when relying solely on serum levels without considering biomarkers like methylmalonic acid (MMA) or homocysteine. The science hasn’t been fully updated in clinical practice to reflect these nuances, which could exaggerate perceived risks or not catch insufficiencies before they cross the line into deficiency. Whenever I counsel someone and want to check their B12 status, I never use the serum B12 test; I always use the "Gold Standard" MMA test, and this should be standard practice in the medical field, but it isn’t.

B12 deficiency is a tough one to determine based solely on symptoms because the body can store B12 for years, even decades. So after a person stops consuming foods fortified with B12 and switches to an unsupplemented vegan diet, it could take a very long time until symptoms develop. But it is possible to prevent this from happening if the person lives in such a way as to allow their body to make enough B12. But not all vegans and raw vegans know how to do this; here their educational community has failed them. So the absence of symptoms doesn’t negate the risk of subclinical deficiency, which can progress if unaddressed. The science here isn’t outdated; it’s incomplete and context-dependent, but the risk for vegans is real and evidence-based, and can be recognized by those who are capable of comprehending the facts where their judgment hasn’t been colored by various biases.

Now, to the question of is there fearmongering around B12 deficiency. I somewhat agree with the author. The framing of B12 deficiency in popular media and health guidelines can amplify fear, especially for vegans. Nutritional guidance often emphasizes that vegan diets are inherently “incomplete” without B12 supplementation, which can feel dogmatic and dismissive of individual variation. Lists of deficiency symptoms – sometimes including vague complaints like fatigue, brain fog, or even psychosis – can indeed seem overly broad, as Hayes notes, potentially leading to overdiagnosis or incorrect self-diagnosis. This can create a narrative that veganism is inherently risky, which may feel like fearmongering to the advocates of plant-based diets. So the tone of the messaging could be refined to avoid stigmatizing veganism, but the underlying concern is grounded in evidence.

But the counterpoint to the charge of fearmongering is that public health messaging aims to prevent harm, and B12 deficiency can and has had severe, irreversible consequences, like neurological damage. Emphasizing the need for supplementation in our modern society is less about fearmongering and more about acknowledging a biological reality: Today, as opposed to 50,000 years ago, we're not drinking from natural streams or eating foods directly from the soil, both of which can contain B12-producing bacteria; back then these microbes could provide small amounts of B12, small but enough. And maybe back then there was more efficient recycling of B12 in the body (via the enterohepatic circulation) and this could have reduced the body's B12 demand back then. And today we're under more stress than those days, and stress gobbles up B12. So today, if not consuming foods fortified with B12, it is indeed possible to bump up against a B12 insufficiency. And that's why knowledgeable educators and practitioners recommend vegans monitor their MMA.

And "snake oil"? Hayes’ claim that B12 supplements are “cyanide snake oil” (due to cyanocobalamin’s cyanide molecule) is misleading; the cyanide is present in trace amounts and poses no health risk at recommended doses. But never-the-less, most knowledgeable educators and practitioners recommend the methylcobalamin form of B12 which does not contain any cyanide, but there’s no mention of that in the book... a red flag for me.

Bottom Line: Is the evidence for B12 deficiency in vegans solid? Yes, which undercuts Hayes’ broader claim. Studies consistently show that vegans who don’t supplement or consume fortified foods have a higher risk of B12 deficiency, with measurable impacts on serum levels, homocysteine, and methylmalonic acid. For example, a 2019 meta-analysis found that 30-40% of unsupplemented vegans had low B12 levels, with some showing clinical symptoms like anemia or neuropathy. And in my practice I have personally seen such cases. Case studies of severe deficiency in vegan populations (infants or long-term unsupplemented vegans) further confirm the risks. While Hayes argues that the prevalence of deficiency is exaggerated, the data suggest it’s a genuine concern, particularly for long-term vegans or those in regions with limited access to fortified foods, and of course to raw vegans who don't consume any processed vegan foods that may be fortified with B12. And if vegans consume alcohol or garlic, or don’t get enough dietary cobalt, or experience lots of stress, this increases the odds of a B12 insufficiency. Vegans who dismiss these facts out-of-hand risk undermining their own health somewhere down the road, and educators and authors who disseminate inaccurate B12 info are violating the most important tenet of the Hippocratic Oath: "First, do no harm".

In conclusion, Hayes’ skepticism is valuable for questioning dogma and highlighting how nutritional science can be influenced by institutional biases or commercial interests. Her exploration of historical inconsistencies and overly broad symptom lists is a useful critique, as is her call to empower vegans to navigate health advice critically. However, her dismissal of B12’s importance veers into overreach. Questioning whether B12 is a “true vitamin” or suggesting deficiency fears are largely a myth ignores robust evidence of its biological necessity and the measurable risks of deficiency in unsupplemented plant-based diets. Her conspiratorial tone (“cyanide snake oil”) risks undermining her stronger points about marketing and diagnostic flaws. So while the fear of B12 deficiency can be amplified by overly broad symptom lists and hyped-up marketing by supplement companies, and some diagnostic practices rely on outdated or imprecise metrics, the core concern about B12 deficiency in veganism is grounded in solid evidence. So Hayes’ critique is a useful starting point for discussion but overstates the case by downplaying the evidence for supplementation’s necessity for some people. My advice? Check your MMA level twice a year. More info about that in my B12 article.

Don Bennett is an insightful, reality-based author, and health creation counselor who uses the tools in his toolbox – like logic, common sense, critical thinking, and independent thought – to figure out how to live so we can be optimally healthy.