Vitamin B12 and Veganism / Vegetarianism
Probably the most heavily discussed topic surrounding vitamin B12 is whether vegans and vegetarians are reliant on a supplementary provision of the vitamin or not.
Why is this such a hot topic? The discussion lies at the heart of other debates, namely arguments concerning which diet is really the most natural for humans.
Vitamin B12 is integral to this discussion about the most natural diet. For example, if a vegan or vegetarian were to incur a B12 deficiency and had not been supplementing their intake artificially, a meat-eater would deem this proof that such diet choices are unnatural and unhealthy – in their eyes a direct result of not eating meat. However, some vegans strongly disagree and try to prove the opposite.
In our view this discussion about ‘natural nutrition’ completely misses the point because veganism and vegetarianism are usually adopted for personal and ethical reasons. The health implications of a vitamin B12 deficiency are very serious and are not relevant to an emotional discussion, but rather should be seen from a nutritional and health viewpoint.
These are the main questions raised from a health perspective:
- Is a vegan/vegetarian diet healthy and can all the necessary nutrients be obtained from this?
- Is a supplementary intake of vitamin B12 advisable for vegans/vegetarians?
- Is a diet containing meat/fish/dairy products healthy and which advantages and disadvantages are to attributed to this?
It has now be scientifically proven that a vegan or vegetarian diet can be extremely healthy. It is recommended by almost all health experts and authorities as particularly beneficial to health, so long as balanced and comprehensive food choices are made.1 Certain diseases are found to heal quicker when switching to a more plant based diet, particularly cholesterol related diseases and so-called lifestyle illnesses suspected to be closely associated with excessive meat consumption.
But what is now equally clear, is that vegetarians and vegans especially should give their vitamin B12 intake careful attention. This article will provide more detailed information on the topic.
Vitamin B12 in Vegetarian and Vegan Diets
Official recommendations advise that adults require around 3 micrograms of B12 per day. In our view, the actual intake should be much higher in most cases. This is due to the fact that most absorption capacities in adults are less than the ideal, meaning a large amount of the ingested vitamin goes unabsorbed and is excreted.
Vitamin B12 is found almost exclusively in animal foods and most concentrated in offal, where anything up to 65 μg per 100g can be found. Offal has become increasingly unpopular and is of course not eaten by vegans and vegetarians, which has resulted in a higher deficiency risks in vitamin B12.
It is also worth pointing out, however, that often sources that are considered high in vitamin B12 (beef, pork, chicken and fish) usually only provide relatively small amounts. Long-term studies have shown that those who do not eat large amounts of these foods and might also require an increased B12 dose (i.e. due to stress) or who have a weakened absorption capacity, can quickly develop a deficiency despite eating meat in their diet.2
Some forms of vegetarianism, such as ovo-lacto, include two very potent sources of vitamin B12, cheese and egg. However, this still may not be enough to meet the needs of those requiring an increased intake. Veganism does not include these two sources of course, which is why vegans are advised to obtain a direct supply through taking nutritional supplements.
This is even recognised by the international Vegan Society, who have brought out their own range of supplements called Veg1. They recommend using a daily supplement containing a minimum B12 value of 10 μg, or a weekly supplement containing at least 2000 μg. In addition, they recommend making sure to consume fortified plant foods.3
Vitamin B12 Deficiency in Vegans and Vegetarians
Many studies have looked into whether vegans and vegetarians are more likely to suffer from a B12 deficiency than omnivores. The results are quite conclusive: a deficiency amongst vegans is extremely common and also the percentage of vegetarians with a shortage is significantly higher than in omnivores.4-6 In old the figures for omnivores and vegetarians become increasingly similar, but vegans have an extremely high deficiency risk at all times.7,8
A popular argument from vegans is that the number of meat eaters suffering from a deficiency is much higher than the number of vegans that are. While this is true in absolute terms, it’s important to bear in mind that only around 0.5% of the US population are vegan, meaning total deficiency numbers will naturally be higher in meat eaters.
If you look at the percentages, however, it’s clear that B12 deficiencies are much higher amongst vegans and vegetarians that in other diet types. Around 7% of the total population are suffering from a lack of vitamin B12, yet between 60 – 90% of vegans are deficient. Even studies carried out by vegan advocacy groups came to the same conclusion, so bias can be ruled out.9
The risk of B12 deficiency faced by vegetarians is also still quite high. The result of studies in this field are a little more diverse, concluding that anything from 20 – 70% of vegetarians might be suffering from a lack of B12, which on average means that half of all vegetarians are affected.
It can therefore be regarded as a scientifically proven fact that veganism and vegetarianism pose higher risks of vitamin B12 deficiencies. The larger vegan associations promote the awareness of this, since the high of number of studies carried out on this topic clarify the risks in no uncertain terms. For this reason it is all the more surprising that some vegan forums and articles downplay the serious potential health risks, most commonly in discussions concerning ‘natural diets’ as mentioned above. In these cases the risk is often ignored and results in a deficiency.
Vitamin B12 deficiencies often go undetected for a long time before serious physical symptoms start to manifest. For many years, symptoms such as fatigue, depression and minor mouth inflammations could be the only outward signals, but these are rarely identified as an indication of a B12 deficiency. The more severe symptoms might only first become noticeable after 10 years, which is why sufferers often live under the false impression that they are fine for long periods of time.
The rest of the article will detail how vegans and vegetarians can ensure they are getting an optimal supply of vitamin B12. It is also worth calculating how much B12 is taken in with food, to work out how much is needed in supplements.
Vegetarian Sources of Vitamin B12
Some ovo-lacto-vegetarian foods contain enough vitamin B12 to cover at least some of the body’s daily need. However, this is assuming that there is no increased need due to, say, problems involving poor absorption, which is the case for a surprising number of people.
We believe that in most cases the intake of B12 should be higher than the daily requirement, because, as explained above, not all ingested B12 is utilized by the organism. In our opinion healthy people need an intake around 4 – 5 times higher than the currently recommended daily amount. Those who have problems with absorption (a common occurrence), particularly in the stomach lining, could require anything up to 300 times more than the suggest value.
% recommended daily allowance in adults
Egg yolk (chicken)
Cream cheese (min. 10% fat)
Egg white (chicken)
Vegan Sources of Vitamin B12
The many discussions regarding whether vegan diets meet the needs of our B12 requirements has led to the circulation of various different theories and assertions and has also resulted in a number of scientific studies being carried out. Fortunately, these have allowed vitamin B12 to be better understood. In the following subsection, several reported and actual vegan vitamin B12 sources will be examined more closely.
Vitamin B12 Fortified Foods
As an intermediary between supplements and actual foods, there are vitamin B12 fortified foods. Examples of these include corn flakes, soya milk, soya yoghurts and puddings, juices, some meat replacement products, yeast extract and most energy drinks. The vitamin B12 content in each of these varies.
Under current EU regulation it is prohibited to fortify organic produce, only foods from conventional farming methods can be treated in this way. It is worth noting that most of the vegan and vegetarian population preferentially consume organic produce.
The table below details approximate values for some of the above mentioned products, but the B12 content varies per manufacturer. It should also be noted that not all of the listed products always contain vitamin B12, only those that have been specifically modified. If in doubt, check the packaging or contact the manufacturer.
Vitamin B12 content µg/100g
Vitamin B12 content µg/portion
Meat substitute products
Some of these enriched products can provide some of the body’s daily requirement of B12 for vegans, but as a sole supply these foods won’t be enough as the concentration levels are low. Some are questionable sources due to other negative impacts they may have on our health (e.g. energy drinks) and others have been questioned for not provide much by way of biologically usable B12 (e.g. fruit juice).
Vitamin B12 From Intestinal Bacteria
Vitamin B12 is produced exclusively by microorganisms. Some of these bacteria are found in the human intestine and can produce large quantities of vitamin B12. However, this source of B12 cannot be relied upon even if the body is taking in sufficient amounts of the vitamin and is in full health.
There are only certain places in the body that vitamin B12 can be absorbed and these are via the oral mucosa in the mouth and and in the small intestine. The majority of B12 secreting bacteria are found in the large intestine and at this point the possibility of absorption has passed. As a result, vitamin B12 produced in the large intestine goes unused and is excreted with the faeces.
Additionally, the gut flora and the absorption capability of most people is so impaired that B12 produced in the body is not a suitable source. A vegan B12 supply in such a way is very rare and would only be possible in very special circumstances – for more information, please refer to our article entitled vegan vitamin B12.
These findings may provide a possible explanation as to why most vegetarian animals consume their own faeces at certain intervals. Like humans, all animals are dependent on an intake of vitamin B12. It was initially unclear how herbivores in the animal kingdom were able to meet their B12 requirements. While ruminants such as cows are able to maintain a sufficient supply of cobalt from self producing bacteria in their rumens which they can then absorb, other herbivores rely on a supply of B12 from their diets. Today it is assumed that this is achieved through sporadic consumption of their own faeces and through eating faeces that contain microorganisms, earth and contaminated pieces of plant.
This isn’t really considered a viable vitamin B12 source for humans, as aside from the obvious health risks, it is unlikely that most people would be able to bring themselves to take part in such a practice.
Vitamin B12 Found in Soil
In good quality humus, such as that present in organic farming, vitamin B12 producing microorganisms can be found.10 By consuming unwashed and unpeeled root vegetables like carrots and parsnips grown in these soils, a significant amount of vitamin B12 can be obtained.
The amount of B12 available from this method has not yet been investigated, as unwashed organic food is predominantly used in the home. There are also likely to be a number of variables, such as the soil quality and the type of microorganism, meaning a general value would be hard to determine. It is unlikely that this source would cover the body’s requirement, but it could certainly make up a significant amount and constitute a valid source. This might have been the case in the past, but now as a result of poor soil quality and high use of pesticides, it plays almost no role.
Vitamin B12 Found in Vegetables
No vegetable exists that is known to contain a significant amount of self produced vitamin B12. But it has been shown that plants can absorb and store B12, for example in lab experiments using a highly concentrated vitamin B12 solution or when fertilized using fertilizer that is extremely rich in vitamin B12.11
Vegetables grown on strictly organic farms could therefore absorb amounts of B12 from fertilizer (e.g. cow manure).
Crops could be farmed in such a way that their roots, tubers and partly their leaves could contain decent amounts of vitamin B12. But since it is easier to simply directly enrich foods there are currently no plans to develop this idea.
It can be assumed that by eating organic whole foods, small amounts of vitamin B12 will be absorbed. The scale in this circumstance might be about 0.1 μg / 100g would be an unreliable and insufficient source unless several kilos of these raw vegetables were consumed daily. Nevertheless, if eaten in conjunction with other B12 supplies, this could be another small way for vegans to help to avoid low B12 levels.
Vitamin B12 in Yeast
Yeast (nutritional yeast) does not naturally contain vitamin B12. The common misconception that it does, is probably due to the fact that a few different yeast products are fortified, such as the well known yeast extract spread Marmite. It might also be because some US nutritional yeast brands culture their produce in a special nutrient medium and as a result the product contains small amounts of vitamin B12. Nutritional yeast produced in Europe does not contain vitamin B12, unless it has be specifically fortified for this purpose.
Vitamin B12 in Algae: Spirulina, Chlorella and Nori
Algae is central to the discussion on sourcing vitamin B12 suitable for vegans. Some algae, specifically spirulina, chlorella and nori are believed to be an excellent source of vitamin B12 and are often advertised as such.12 In light of recent studies, however, just how usable these algae are as a B12 source for humans has become extremely controversial. The market for these products is extremely lucrative and in this particular field there are many studies and counter studies, so this topic should be handled with care.
To understand how algae could be a rich B12 source, it is also necessary to understand the procedures used to measure content and levels in plants. In the past, a microbiological assay was used to calculate vitamin B12 food content, so with bacteria and algae the corrinoid content necessary for B12 growth was measured. A number of substances that share similar molecular structures come under the term ‘corrinoid’ – including vitamin B12. This method can only measure the total corrinoid quantity and not the proportion of corrinoids that are biologically available to the body as vitamin B12/cobalamin.
Today, vitamin B12 content is measured by differential radioassay and more recently through IAC-HPLC (Immunoaffinity column – high-performance liquid chromatography). These test are able to more effectively differentiate between vitamin B12 and other corrinoids.
The stated high levels of vitamin B12 in algae such as spirulina are the result of tests carried out by manufacturers using almost exclusively microbiological assays. In reality these tests do not determine B12 content, but rather corrinoid content. When comparing these results to those from a radioassay extreme differences can be seen, making it clear that around 80% of the alleged B12 that was measured were actually vitamin B12 analogues that are biologically inactive in humans.13 Tests carried out by the Vegan Society concluded that spirulina was not a reliable B12 source, as it did not improve MMA levels.
Studies have shown that although consumption of spirulina and nori temporarily increases the blood serum levels of B12 (although this test does not differentiate B12 analogues), patients’ MMA levels (metabolic product of B12 and clear indication for its presence) significantly deteriorated.14 This is often explained by the fact that high levels of B12 analogues will hinder the uptake of actual cobalamin, thus lowering the total absorption.
So far studies suggest that only chlorella may actually be a legitimate and substantial source of vitamin B12.15
Until precise knowledge and conclusive studies are available for this topic, it should be assumed that algae does not reliably contain vitamin B12.
There are a variety of different fermented foods currently widely available, cultured either through the fermentation process or mould cultures. Tempeh, sourdough, sauerkraut and beer are examples of such products that are also considered a source of vitamin B12.
Despite the wide belief that soy sauce, tamari and tempeh contain vitamin B12, in tests they were shown to have no content. It is unclear how this reputation was established.
For sourdough and sauerkraut there are no reliable values available. When testing sauerkraut, microbiological assays repeatedly determine values under 0.5 μg / 100g, but the portion of this that represents actual vitamin B12 is unknown.
According to CMA, vitamin B12 content in beer is 0.8 μg / 100g, however, for obvious reasons it is not advisable to consume large quantities of beer in order to obtain a vitamin B12 supply.
Parsley, Seaberry and Wheatgrass Juice
A few different values have been suggested for vitamin B12 content in parsley, seaberry (seabuckthorn) and wheatgrass juice.16 It is unclear whether content is a result of contamination and it is also questionable as to how rich the content is.
It is most likely that contamination is the cause for any B12 content in these three plants. The company Dr. Pandalis sold seabuckthorn vitamin B12 capsules for many years until they had to release a statement revealing: “seabuckthorn produced by our organic farmers has not been shown to contain vitamin B12 for around the last four years.”
Even since this revelation, the rumor that seaberry can be a reliable source of vitamin B12 has remained popular.
Wheatgrass and other similar plants belong to a group that have produced positive findings to suggest that they may indeed be a source of vitamin B12. However, there is currently still not enough reliable information surrounding the topic. It is also unclear here as to how this B12 is obtained from the earth, furthering the belief that it is most probably as a result of contamination.
Vitamin B12 from Food Supplements
Based on current knowledge, a vegan supply of vitamin B12 is very difficult or even impossible to come by.
Fortified foods are not available organically, which rules them out as an option for many vegans. It is also often unclear which form of cobalamin the food contains and how it might react with other ingredients. This is certainly the case for fruit juices, it is questionable how biologically usable vitamin B12 would be for humans after coming into contact with high doses of vitamin C and other acids.
With this in mind, we would support the advice of the Vegan Society, who suggest taking vitamin B12 supplements if you follow a vegan diet, as the only secure way to avoid a vitamin B12 deficiency. B12 supplements may not be cheap, but they are also not too expensive, dosages are easily measured and an overdose is almost impossible, so there is really no reason why vegans should take the risk of developing a deficiency. Life quality and vitality can often increase drastically when the body’s vitamin B12 supply is increased.
For vegetarians, specific diet details play a large role. Those who want to make sure they aren’t at risk can do so by taking an MMA urine test to monitor levels.
Are Vitamin B12 Supplements Vegan?
Vitamin B12 supplements are produced in bacterial cultures, which are almost always vegan.17 It is commonly thought that B12 is obtained from animal organs, but to manufacture this way on a large scale is ruled out for practical reasons. Nevertheless, it is important to check if you are vegan that the supplements you choose do not contain ingredients such as lactose or gelatine, which would of course not be suitable.
According to wikipedia, some manufacturers want to use genetically modified bacteria to culture B12, as it can supposedly produce more. Unfortunately there is actually no evidence for this and only the respective manufacturer can clarify the matter further.
1 American Dietetic Association; Dietitians of Canada: Position of the American Dietetic Association and Dietitians of Canada: vegetarian diets. In: Can J Diet Pract Res., 64(2):62-81; Sommer 2003. PMID 12826028, Übersetzung des VEBU.
2 Judy McBride (2). “B12 Deficiency May Be More Widespread Than Thought”. Agricultural Research Service. United States Department of Agriculture. Retrieved 2 July 2012.
3 Vegan Society. What Every Vegan Should Know About Vitamin B12. http://www.vegansociety.com/lifestyle/nutrition/b12.aspx
4 Herrmann W, Schorr H, Obeid R, Geisel J. Vitamin B-12 status, particularly holotranscobalamin II and methylmalonic acid concentrations, and hyperhomocysteinemia in vegetarians. Am J Clin Nutr 2003;78:131–6
5 Ibrahim Elmadfa and Ingrid Singer: Vitamin B-12 and homocysteine status among vegetarians: a global perspective. Am J Clin Nutr 2009 89: 1693S-1698S
6 Refsum H, Yajnik CS, Gadkari M, Schneede J, Vollset SE, Orning L, et al. Hyperhomocysteinemia and elevated methylmalonic acid indicate a high prevalence of cobalamin deficiency in Asian Indians. Am J Clin Nutr 2001;74:233-241.
7 Aśok C Antony Vegetarianism and vitamin B-12 (cobalamin) deficiency. Am J Clin Nutr 2003 78: 1 3-6
8 Zouë Lloyd-Wright, et. al.: Holotranscobalamin as an Indicator of Dietary Vitamin B12 Deficiency Clin. Chem. 2003 49: 2076-2078
9 Stephen Walsh, PhD: B12: An essential part of a healthy plant-based diet 35th World Vegetarian Congress http://www.scienzavegetariana.it/rubriche/cong2002/vegcon_B12_en.html
10 Robbins WJ, Hervey A, Stebbins ME. Studies on Euglena and vitamin B12. Science 1950(Oct 20):455.
11 Mozafar A. Enrichment of some B-vitamins in plants with application of organic fertilizers. Plant & Soil. 1994;167:305-311
12 Watanabe F, Takenaka S, Kittaka-Katsura H, Ebara S, Miyamoto E. Characterization and bioavailability of vitamin B12-compounds from edible algae. J Nutr Sci Vitaminol (Tokyo). 2002 Oct;48(5):325-31. Review.
13 Dagnelie PC, van Staveren WA, van den Berg H. Vitamin B-12 from algae appears not to be bioavailable. Am J Clin Nutr. 1991;53:695-7.
14 Yamada K, Yamada Y, Fukuda M, Yamada S. Bioavailability of dried asakusanori (porphyra tenera) as a source of Cobalamin (Vitamin B12). Int J Vitam Nutr Res. 1999 Nov;69(6):412-8
15 Chen JH, Jiang SJ. Determination of cobalamin in nutritive supplements and chlorella foods by capillary electrophoresis-inductively coupled plasma mass spectrometry. J Agric Food Chem. 2008 Feb 27;56(4):1210-5. Epub 2008 Feb 2.
16 van den Berg H, Dagnelie PC, van Staveren WA. Vitamin B12 and Seaweed. Lancet Jan 30, 1988.
17 Martens JH, Barg H, Warren MJ, Jahn D (2002). Microbial production of vitamin B12. Applied Microbiology and Biotechnology 58 (3): 275–85.