Plant-Based Mistakes

Whilst I’d maintain that the biggest dietary mistake we can make is to continue eating animals rather than plants, there are some pretty serious blunders that can be made by those who eat nothing but plant foods. This may especially be the case if you regard yourself as a vegan rather than a WFPBer (if such a word exists!) and don’t place your own and your family’s own health above or, at least, equal to the other reasons that you define yourself as a vegan.

A Specifically Vegan Mistake?

If vegans are only going plant-based because of concerns about animal rights and/or the environment, without considering the nutritional value of their own new diet, they usually end up eating highly-refined carbohydrates – pasta, bagels, bread, commercially-prepared ready-meals etc – and not a balanced wholefood diet.

As we’ve discussed previously 1 , replacing meat with refined carbs is not the way to get optimal health benefits and some suggest that you may as well eat animals if your diet is largely processed junk and lacks the green stuff.

A General Plant-Eater’s Mistake #1?

A mistake that all plant-eaters can make is to ignore nutritional priorities. That is, to think that simply by eating a balanced plant-based diet (even if it’s completely wholefood with no added sugar, oils and salt) you’re destined to get all the nutrients your body needs to avoid potentially dangerous health conditions. The nutrients generally considered of particular concern for plant-eaters include:

  • protein
  • iron
  • zinc
  • calcium
  • iodine, and 
  • vitamin D

I don’t have much time for worrying about the first four items. Without eating animals, legumes alone provide a rich form of protein, iron and zinc, and green vegetables (some say an emphasis should be on low-oxalate 2 green veg) are an excellent source of calcium, along with some nuts and seeds.

However, iodine and, especially, vitamin D are not to be ignored. You can’t get the former from plants and getting the appropriate amount (not too much and not too little) of the latter can be something of a minefield, as we saw in previous blogs 3 4 . So, what’s to be done?

Well, regarding iodine, you can take a supplement and/or eat appropriate amounts of those foods (e.g. wakame) that are considered reasonably okay in moderation.

Regarding vitamin D, whether or not you eat fortified foods on a plant-based diet, this absolutely essential vitamin can become a real problem if, of course, you don’t get lots and lots of good, warm sunlight exposure on a regular basis. We looked at vitamin D in previous blogs 5 6 , and ignoring its importance is not to be advised, although enough people (plant-eaters and omnivores) are known to do so at their peril 7 .

Below, I’ll mention a potentially good supplemented source of iodine and vitamin D.

A General Plant-Eater’s Mistake #2?

Whilst I could have covered this one in the above list, it always seems like one nutrient that deserves special mention –vitamin B12.

B12 is a potentially big problem for vegans and, for that matter, even for someone eating the optimum WFPB diet if, that is, they don’t supplement B12. Whilst B12 is made by microorganisms, and we have billions of these living inside us, those that make B12 in our bodies happen to be low down in the large intestine. So, unless we eat our own poo (not to be recommended – do I even need to remind you of that?!), the B12 we produce is either absorbed by bacteria within our lower intestine or discharged as faeces.

Interestingly, at least one research study 8 found that some people who eat negligible amounts of dairy and meat (in this particular study, rural Iranians), had quite high B12 levels (~411 pg/ml average), with no apparent cases of megaloblastic or pernicious anaemia – both of which are just two of the results of B12 deficiency. It was thought that these Iranians’ low-protein diets encouraged B12-producing bacteria to rise up from the colon (large intestine) to the ileum (the lower part of the small intestine) where the body can effectively absorb the B12 for its own use. This is still an area of uncertainty, since it may be that they picked up sufficient B12 through contamination, being that they lived among their animals and the faeces the animals produced.

Which Plants Provide B12?

There are some plant foods that are known to provide some B12 – such as sea plants (e.g. wakame), blue-green algae, yeasts (e.g. brewer’s yeast), and fermented plant foods (e.g. miso, tempeh or tofu) – but they are not a reliable source . Getting B12 from these rather than a daily B12 supplement is NOT recommended by me or by the likes of Dr Greger, Dr T Colin Campbell, Dr John McDougall et al.

Variation. Variation.

Apart from anything else, you can’t be sure about the amount of B12 in any single food product. For instance, tempeh produced in wooden barrels in Indonesia is reported 9 10 to have some B12 that can be absorbed by our bodies, but when it’s produced in very clean stainless steel vats (as in the US), the resulting tempeh is unlikely to contain much if any B12.

Active vs Inactive B12

Another complicating factor with B12 is whether or not it’s the active or inactive form 11 12 of cobalamin (the general term used for different forms of B12) .

The latter, inactive forms, can bind to the B12 receptors in our bodies and effectively block much of any active B12 from finding an available receptor, with the result that B12 is not absorbed efficiently by the body – leading to a functional B12 deficiency.

So, for instance, when you dry seaweed, some of the active B12 is turned into the inactive form. Another example is chlorella (a type of green algae): whilst this is regarded by some as a useful source of B12, there’s simply not enough evidence yet to prove that this can be used as a sole source of B12 for plant-eaters who don’t use B12 supplements or eat B12 fortified foods.

Playing Russian roulette with the permanent damage that can result from chronic B12 deficiency is not a sensible option.

Although it’s increasingly clear 13 14 that there’s a worryingly high level of B12 insufficiency and even deficiency within the general population, and the Institute of Medicine in the US recommends 15 that everyone over the age of 50* shouldn’t rely on animal foods alone for B12, it’s generally considered 16 that the likelihood of finding B12 deficiency in different dietary groups is as follows (from least likely to most likely):

  • omnivores
  • lacto-ovo vegetarians
  • vegetarians
  • vegans
  • raw vegans

Over 50’s & B12 Deficiency

* When you eat animals, the B12 is physically bound to the animal protein; however, in order to cleave off the B12 from the protein, you need to be producing enough stomach acid and enzymes so you can absorb the B12 into your bloodstream. The problem is that it’s estimated 17  that up to 30% of people aged over 50 don’t produce enough, and so even eating lots of animals doesn’t guarantee healthy B12 levels as we age. And this is important stuff for all of us, since dementia is known 18  to be one of the results of B12 deficiency.

Mothers, Babies, Infants & B12 Deficiency

Of course, at the other end of the age groups, as we’ve discussed in considerable detail 19 pregnant women and infants also need to be really careful about B12 levels, since deficiency can result in irreversible brain damage in the baby 20 and serious health conditions in infants 21 . As pointed out in a previous blog 22 , it’s really important for potential mothers to be informed about the real dangers for their babies if they (the mothers) don’t get the balance right between folic acid (vitamin B9) and vitamin B12 .

They Missed Out WFPB!

You may have noticed that WFPB was not in the above list (from omnivore down to raw vegan). Well, if you’re eating a WFPB diet, you may find that fortified foods are not very common in your diet – indeed, when you make your own plant milks (or choose non-fortified versions), make your own bread (or even your own flour), and avoid commercially-produced breakfast cereals, read-meals, tinned beans, etc etc, you may be eating no fortified foods at all. And, in any case, the amount of fortification of many vitamins within fortified foods is likely to be far below your daily requirements. I guess this means that some WFPBers can be at a similarly high risk of potential deficiencies as raw vegans if, that is, they don’t take appropriate measures.

B12 Supplementation & WFPB Diet

So, when eating a WFPB diet, it’s time to look very seriously at supplementation as being probably the most reliable and sensible route. As I’ve mentioned in some detail previously 23 , one option is the Vegan Society’s Veg-1 supplement which some authorities would and some would not regard as containing sufficient B12. Of course, there are other mixed supplements and single B12 supplements available. My personal approach, at the moment, based on my research, is to take Veg-1 for its iodine and vitamin D content as well as a separate 1000 mcg/μg 24  B12 supplement at least twice a week if it’s cyanocobalamin or daily if it’s methylcobalamin 25 .

Difference Between Different Types of B12 Supplements

Vitamin B12 supplements are usually derived from two sources: methylcobalamin or cyanocobalamin.

Chemically, these are almost identical, with each containing a cobalt ion with a surrounding corrin ring – so called because it’s the ‘core’ of the B12 cobalamin. The cobalt ion has a methyl group stuck to the cobalt ion, while the the cyanocobalamin has a cyanide molecule (don’t worry, it’s not poison in this form!) – hence the names of each.

Cyanocobalamin is a more stable synthetic form 26 of B12 not found in nature, and is used more often in supplements: it’s also cheaper to manufacture. It gets converted into either methylcobalamin or adenosylcobalamin when it enters the body.

In humans, methylcobalamin and adenosylcobalamin (not used so much in supplements) are the two active forms of B12 27Methylcobalamin is in supplements and can also be found in animal foods, although not in predictable quantities, of course.

Final thoughts

You have to have been living under a stone not to know by now that there’s tons of solid evidence that a healthy and balanced plant-based diet beats the pants off an animal-based diet if, that is, you want optimal health and don’t just want to give in to the addictive taste temptation of meaty/fatty/salty food that so many consider the be all and end all of what human nutrition is all about.

Therefore, so long as you’re careful to take into account the importance of the above nutrients (as well as take appropriate steps to prevent any deficiencies), you can dive into your G-BOMBS 28 or your Daily Dozen 29 with gay abandon.

Finally, and before leaving the Big B12 issue, it’s really worth bearing in mind that, to some extent, we’re straining at a gnat 30 here, by acting as if eating a healthy plant-based diet can generally be a worry compared with eating the usual animal-heavy, processed Western (SAD) diet. I’ll let Dr Greger see us out on this note 31 : “Make no mistake: vitamin B12 is important. But so is keeping our perspective, given the millions who are crippled and die from the onslaught of chronic disease that could be prevented, stopped, and reversed with a B12-fortified, plant-based diet.


  1. Greggs’ Vegan Sausage Rolls – Why Veganism Can Fail []
  2. Vegans & Calcium []
  3. Iodine Deficiency in Vegans []
  4. Vegans and Iodine []
  5. Shining A Light on Vitamin D []
  6. Vitamin D & Vegans []
  7. J Steroid Biochem Mol Biol. Author manuscript. J Steroid Biochem Mol Biol. 2014 Oct; 144PA: 138–145. Is vitamin D deficiency a major global public health problem? Cristina Palacios and Lilliana Gonzalez. []
  8. Halsted JA, Carroll J, Dehghani A, Loghmani M, Prasad A. Serum vitamin B12 concentration in dietary deficiency. Am J Clin Nutr. 1960 May-Jun;8:374-6. []
  9. LWT. Volume 96, October 2018, Pages 513-518. Enhancing vitamin B12 in lupin tempeh by in situ fortification. Judith C.M.Wolkers-Rooijackers, Martha F.Endika, Eddy J.Smid. []
  10. Production of vitamin B-12 in tempeh, a fermented soybean food Article in Applied and Environmental Microbiology 34(6):773-6 January 1978. []
  11. Active B12 testing []
  12. Vitamin B12 deficiency. BMJ 2014; 349. 4 September 2014. []
  13. Science Daily: Genetic Variants Associated With Vitamin B12. September 9, 2008. Harvard School of Public Health []
  14. How common is vitamin B-12 deficiency? | The American Journal of Clinical Nutrition. LH Allen – ‎2008. []
  15. Harvard Medical School: Getting Enough Vitamin B12? April, 2015. Linda Antinoro, R.D., L.D.N., J.D., C.D.E. []
  16. What Are The Biggest Mistakes Vegans Make? by Brenda Davis []
  17. Cognitive Vitality: GUT CHECK: ARE YOU GETTING ENOUGH B12? September 16, 2016 Yuko Hara, PhD []
  18. J Geriatr Psychiatry Neurol. 2005 Mar;18(1):33-8. Neuropsychology of vitamin B12 deficiency in elderly dementia patients and control subjects. Osimani A1, Berger A, Friedman J, Porat-Katz BS, Abarbanel JM. []
  19. Vegan Pregnancy & Parenting []
  20. WebMD: Birth Defects Linked to Low Vitamin B12. By Jennifer Warner. []
  21. Med J Aust. 1979 Jul 14;2(1):1-3. Brain damage in infancy and dietary vitamin B12 deficiency. Wighton MC, Manson JI, Speed I, Robertson E, Chapman E. []
  22. B12 Supplements Are Efficient But Caution With Folic Acid []
  23. Vegan Society Veg-1: Does It Contain Enough B12? []
  24. Microgram terminology. []
  25. Brenda Davis’ Comments on cyanocobalamin and methylcobalamin []
  26. BMJ. Clinical Review. Vitamin B12 deficiency. []
  27. NIH: Vitamin B12 []
  28. Health = Nutrient Intake ÷ Calories []
  29. Dr. Greger’s Daily Dozen Checklist. Michael Greger M.D. FACLM September 11th, 2017 Volume 38 []
  30. Meaning of the phrase “straining at a gnat?” The phrase comes from the words of Jesus, as recorded in the Gospel of Matthew. … He follows this up in verse 24 with the phrase you asked about: “Ye blind guides, which strain at a gnat, and swallow a camel.” []
  31. Vegan B12 deficiency: putting it into perspective. Written By Michael Greger M.D. FACLM on August 25th, 2011 []