I’m not vegan but the “Anti-Vegan Because B12” argument is lame.  B12 insufficiency is largely due to malabsorption, not steak deficiency.

Many people take supps, but somehow anti-vegans think B12 invalidates veganism.  It doesn’t.  Also, 1) tons of B12 in oysters; 2) nori B12 works in humans and rats; and 3) mushrooms still haven’t been ruled out as a legit source.  Whether you consider these foods vegan or not is a different story.  Many non-vegans are B12-deficient, too -> all the steak in the world won’t help if you can’t absorb it.

I’m not undermining the severity of B12 deficiency, just noting some basic facts.

My bias: things like T2DM, obesity, and even some cancers and mood disorders are due primarily to circadian arrhythmia, sleep, & LIGHT… and secondarily to diet.

When it comes to diet, mostly plants plus some animal is optimal for humans in our modern #context, regardless of which Ice-Age Paleo-Fairy Tale™ you subscribe to.  Things like sleep, LIGHT, and activity, among others, seem way more important than debating historical [theoretical] dietary minutiae.

Lastly, this particular debate isn’t “vegan vs. keto.”  THEY’RE NOT MUTUALLY EXCLUSIVE.  “Eco-Atkins” is a thing.  Animals provide a convenient source of LC protein, but it can be done without them.



I thought long about where to set the goal post for this article (and will try not to shift it haha).  Paleo-bro’s lash out hard against veganism, claiming it will literally kill you.

Goal post: veganism won’t literally kill you.

Dr. Garth Davis, author of Proteinaholic, is a vegan physician who has successfully treated many patients with a plant-based diet (not vegan to my understanding, but low animal intake).  Imo, Dr. Davis is one of the rare third breed of vegan: health-based, ethical, but NOT a zealous fanatic.  I requested some of his favorite intervention studies and he kindly obliged.

Here is a brief overview of the studies he provided in chronological order, and my comments.

Exhibit A. Vegetarian diet in mild hypertension: a randomised controlled trial (Margetts et al., 1986)

Context: n=58, omnivorous vs. lacto-ovo-vegetarian for 6 weeks, good study design & intervention.

Despite modest weight gain, it worked.  My only critique is lacto-ovo-vegetarian =/= vegan; eggs and dairy are animal super foods, very nutrient-dense.  Not much information about the baseline diets is reported, so it may have simply been a healthier diet overall.  But avoiding red meat for 6 weeks didn’t literally kill them.  And reduced blood pressure despite modest weight gain is rare and bodes well.



Exhibit B. Intensive lifestyle changes may affect the progression of prostate cancer (Ornish, Barnard, et al., 2005)

Context: fully vegan + comprehensive lifestyle intervention for 1 year.

Experimental group patients were prescribed an intensive lifestyle program that included a vegan diet supplemented with soy (1 daily serving of tofu plus 58 gm of a fortified soy protein powdered beverage), fish oil (3 gm daily), vitamin E (400 IU daily), selenium (200 mcg daily) and vitamin C (2 gm daily), moderate aerobic exercise (walking 30 minutes 6 days weekly), stress management techniques (gentle yoga based stretching, breathing, meditation, imagery and progressive relaxation for a total of 60 minutes daily) and participation in a 1-hour support group once weekly to enhance adherence to the intervention. The diet was predominantly fruits, vegetables, whole grains, legumes and soy products, low in simple carbohydrates and with approximately 10% of calories from fat. The diet is intensive but palatable and practical. In earlier studies most patients were able to adhere to this diet for at least 5 years.”

5 years!

My only critique is that a comprehensive lifestyle intervention is so much more than simply vegan.  In any case, it worked.  And prostate cancer is very serious.  And a WHOLE YEAR of zero red meat didn’t literally kill them.


Exhibit C. A two-year randomized weight loss trial comparing a vegan to a more moderate low-fat diet (Turner-McGrievy, Barnard, and Scialli, 2007)

Context: 2 years! ad lib. ad lib. ad lib.

The low-fat vegan diet consisted of fruits, vegetables, legumes, and grains. Animal products were proscribed, and the use of unrefined foods was encouraged. Participants were asked to limit high-fat plant foods, such as avocados, nuts, and seeds. The NCEP diet followed the former NCEP Step II guidelines, which are similar to the current NCEP Therapeutic Lifestyle Changes diet. There was no restriction on energy intake for either diet group, and participants were encouraged to eat to satiety.”

Interestingly, they showed that those who received regular counseling achieved greater weight loss regardless of diet, but those who received regular counseling and were assigned to vegan lost the most weight.

And TWO WHOLE YEARS of zero red meat sure didn’t literally kill them…



Exhibit D. A low fat vegan diet and a conventional diabetes diet in the treatment of T2DM: a randomized, controlled, 74-week clinical trial (Barnard et al., 2009)

Context: 74 weeks! (fyi that’s longer than a year)

Comments: this study demonstrated non-inferiority.  Both diets worked equally well for long-term weight loss.  Absolute levels of HbA1c were similarly reduced overall, but vegans were able to discontinue more anti-diabetic meds (that’s basically the definition of a “healthy” diet).

And no fatalities, literally, with 74 weeks of no red meat.


Exhibit E. Effect of a 21-day Daniel Fast on metabolic and CVD risk factors (Bloomer et al., 2010)

Context: Daniel Fast = ad lib vegan (no meat, not no food [like real fasting]).

Comments: potentially meaningful changes in blood pressure (similar to Exhibit A), if it works in hypertensive patients.  Reduced inflammation.  And the spontaneous reduction in ad lib food intake is great… had the study lasted longer than 3 weeks, this may have resulted in weight loss.



Exhibit F. Restriction of meat, fish, and poultry in omnivores improves mood: a pilot RCT (Beezhold and Johnston, 2012)

Context: omnivore vs. pescoovovegetarian vs. lactovegetarian for two weeks for 2 weeks.

Comments: No #vegan interventions.  Interestingly, mood improved only in the lactovegetarians (not pescoovovegetarians), but it was modest and only significant in 2 out of 11 assessments of mood.  So, dairy is cool, and literally no fatalities in either of the no red meat groups.


Exhibit G. Comparative effective of plant-based diets for weight loss: a RCT of five different diets (Turner-McGrievy et al., 2015)

Context: this is one of my favorites.  Vegan vs. lacto-ovo-vegetarian vs. lacto-ovo-pesco-vegetarian vs. semi-vegetarian vs. omnivorous diets for 6 months.

Comment: vegans lost the most weight, but lacto-ovo-vegetarians were a close second (see comments from Exhibit A).

-excellent description of different dietary nuances:

sample diets

-actual changes:


dietary profiles

and weight loss:




Exhibit H. Association of animal and protein intake with all-cause and cause-specific mortality (Mingyang, Hu, Willett, Longo, et al., 2015)

This isn’t one of the studies Dr. Garth sent me, but demonstrated an important point imo.

Animal protein is bad, but “these associations were confined to participants with at least 1 unhealthy lifestyle factor based on smoking, heavy alcohol intake, overweight or obesity, and physical inactivity, but not evident among those without any of these risk factors.

***this is the straw that usually breaks the back of many studies.  It’s very difficult to control for all the bad things unhealthy people do (partly bc we don’t know all of the relevant ones), but when we do, spurious correlations evaporate.


[insert Michael Pollan quote here]

[followed by LC addendum]


calories proper


Become a Patron!












Be Sociable, Share!
  • Tuck

    OK, you’ve piqued my curiosity. Is there any actual evidence that the well-recognized B12 deficiency that typifies vegetarian and vegan diets is the result of malabsorption?

    Here’s a case study of ‘possible’ malabsorption from 1978, but there’s little else I can find…

    • Nicolás Flamel

      Good question, I hope Bill can explain further his statement, because in opposite to him, in a recent paper ( the author mentioned that:
      “There is some evidence that an inadequate intake of vitamin B12, rather than malabsorption, is the main cause of this high prevalence of deficiency, although the latter cannot be ruled out because it has not been assessed.”

  • Emergent Economist

    Here you go again with your application of critical thinking and logic . . . if social media has taught you *anything* by now, its that you should only make arguments which support prevailing wisdom / preconceived notions.

  • One example: search “intrinsic factor” and “B12 deficiency.” It’s part of why B12 injections are as popular as they are.


    • Tuck

      Intrinsic factor deficiency is caused by antibodies, and goes so frequently with celiac that it’s usually considered a symptom.

      That doesn’t really explain why Vegans would be prone to Intrinsic factor deficiency…

    • Support Small Farms

      intrinsic factor is also associated with aging, that is older people have less of it and can’t absorb B12 through their stomach lining so they get injections instead.

    • sabelmouse

      some of us need methylcobalamin, in any case.

  • Abu Sumayah Laughton

    The multitude of problems that result from a vegan “diet” aren’t limited to B12 deficiency. Mushrooms only contain trace amounts of B12 and nowhere near enough to satisfy the bodies requirements. Oysters aren’t considered to be compatible with a vegan diet, so to mention them as a potential source is pointless. Here is a simple question that doesn’t require an answer because its axiomatic. Why discuss the issue of B12 malabsorption in vegans when there is only trace amounts of it in their diet in the first place? There is nothing there to absorb! Veganism is self-induced malnutriton, not a diet.

    As for the doctors that put their patients on a vegan diet, then I would ask if there are any LONG-TERM studies. Vegan diets often produce results in the short-term because the body is still holding stores of many nutrients that are depleted over time. Furthermore, anyone who switches from a Western “do you want some fries with that?” diet will see improvements. If a meth addict switches from smoking meth to smoking opium they may see health improvements as well. Doesn’t mean that the opium isn’t harming them! Just means it may be better than meth. Something is up with your critical thinking Bill.

    • Support Small Farms

      Trace amounts of B12 with mushrooms and in dirt, in general, are most likely due to fecal contamination. Other animals, including gorillas and apes get their B12 from eating their own poop (coprophagia). Oysters and other shell fish, like organ meat, are tremendous sources of B12 and other minerals…though, you’re right, vegans won’t eat them (or fish oil as listed in Exhibit B which would provide preformed DHA that may otherwise be gotten via micro algae pills).

      • mike

        That reminds me of this paper…

        with the following hilarious sentence:

        “Human faeces contain appreciable quantities of vitamin B12 or vitamin B12-like material presumably produced by bacteria in the colon, but this is unavailable to the non-coprophagic individual.”

  • Support Small Farms

    Btw this entry refers to “…Paleo-bro’s lash out hard against veganism, claiming it will literally kill you…” Since you appear to be repeatedly referring to this with your exhibits, is there a link to this rant? I went to a Paleo bro site and it’s in a foreign language so couldn’t find whatever you were referring to.

    Regardless, personally having been vegetarian and then vegan, I know a vegan diet won’t kill me. Though for me, such diets were NOT optimal. But that’s still beside the point. Much of the backlash against veganism isn’t because there is any assertion that a diet without meat will kill you. Rather it is the assertion, especially by zealot vegans, that a diet WITH meat WILL kill you. All the epidemiology referenced to support any such assertions for very low ABSOLUTE risk associations doesn’t bolster the arguments of such zealots. No, it’s just annoying.

    • Will

      I don’t think he is referring to a particular person but rather the paleo community in general.

      • Support Small Farms

        Maybe more like a caricature of people in the Paleo community, since a lot of people within the community simply believe a vegan diet isn’t an optimal one for most people.

      • ^^^ correct

  • “Consider the Oyster: Why even strict vegans should feel comfortable eating oysters by the boatload”

  • Matthew Klein

    What do you mean by this: “When it comes to diet, mostly plants plus some animal is optimal for humans in our modern #context…” As far as I know there’s no reason to believe this nor any scientific evidence to back it up. Look at all the anti-nutrients in plants. Even if you’re keto or low carb or low calorie on mostly plants you’d still have to deal with the anti-nutrients.

    • “you’d still have to deal with the anti-nutrients”

      I understand your concern, but this is really more molehill than mountain TBH. Plants have a lot to offer along the lines of nutrition.

      • Matthew Klein

        Yeah you’re right, but are animal products not better sources of all essential nutrients than plant products? That’s the understanding I have come to.

    • George Thomas

      The anti-nutrient meme is overblown. If you’re scared of eating a bowl of lentils because zinc deficiency then you need to re-evaluate where you’re getting your info from . It’s sad how certain diet gurus have scared people out of eating good food like legumes and nuts and seeds and plants because MUH ANTI NUTRIENTS.

      • agree

      • Matthew Klein

        I agree too, the anti-nutrient meme is overblown, but I wouldn’t be so fast to dismiss it as a diet guru thing. There’s a lot of evidence that vegetables and fruits provide no benefit. And, my point still stands that there’s very little evidence to support any benefit of veg over meat. Maybe vegetables in place of processed carbs, sugar, and veg oils – sure.

        Here’s one:

        “The overall effect of the 10-week period without dietary fruits and vegetables was a decrease in oxidative damage to DNA, blood proteins, and plasma lipids, concomitantly with marked changes in antioxidative defence.”

        And a nice write up with others here:

        Good review here:

        Also, from an evolutionary perspective, I find it hard to accept the “eat mostly plants”…that simply never occurred on any large scale for humans pre-agriculture, so I’m wary of recommending it as a dietary paradigm.

        Roughly 500 generations have existed under agriculture out of roughly 6,000 generations of modern humans and 70,000 generations of the genus Homo. Certainly they were eating some plants, but actually not much up until ag and definitely not mostly plants.

        Radio isotope analysis indicates that humans ate mostly meat up until the development of agriculture.

        • Matthew Klein

          Scaring people out of eating nuts and legumes and “good food” is a different question – one about establishing a dietary paradigm. I think a socially healthy diet would include such foods and normal people looking for health benefits should not overly stress themselves out by avoiding too many things! But that is a different story from the science, which as you can see from my sources in combo with Bill’s, that the results are inconclusive at best as to whether there is an actual benefit of eating plants.

  • supplement manufacturers know what’s up: they usually contain WAY more B12 than the RDA *to account for* poor absorption

    • Daz

      & most offer sublingual b12 options, for the same reason I guess

  • “need =/= optimization”

    Essential to survive?


    Essential to thrive?

    My bias is for the latter, which is why I advocate omnivory.

  • The health advantage of a vegan diet: exploring the gut microbiota connection