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Prevent Vitamin B12 Deficiency on a Vegan Diet | Soul in the RawB12 deficiency is an incredibly serious issue. Unlike you may have heard, it is not only a danger for vegans. Actually, currently, the population at large is at risk for this deficiency because of its bioavailability, or how well the body can absorb B12 from food, is very low. New studies show that the bioavailability of B12 is as low as 4% from eggs, for example.

But when it comes to vegans, B12 deficiency is a particularly urgent issue, with horrific consequences. Recent studies have found that more than 50%-60% of vegans are B12 deficient. The kind of deficiency that is so bad, that your body isn’t working properly anymore.

There are simple and easy ways to prevent deficiency and even combat it (if it’s not too late, and there is no irreversible damage). In this post, you will learn some B12 myths, and how to easily protect yourself and your family from the horrible damage that can be caused by B12 deficiency.

What is Vitamin B12?

Vitamin B12 is an essential vitamin, meaning you must obtain it from outside sources. B12 is a cofactor and catalyst of many enzyme processes, and almost every cell in your body needs B12.

It is used for cell metabolism and division, production of hemoglobin, protein, DNA, RNA, lipids, and hormones. It plays a role in heart health, brain and nervous system function, mood, and bone growth and development.

B12 also helps in carbohydrate break down, so a deficiency can lead to high blood sugar, and processing fat, so B12 deficiency can lead to an unhealthy lack of fat.

It is a water-soluble vitamin and contains cobalt in its molecular structure, which is why it is also called cobalamin.

There are four forms of B12, which differ by the side group attached to the cobalamin molecule:

  • Hydroxycobalamin, produced naturally by bacteria and usually found in B12 shots, and easily converts to methylcobalamin.
  • Methylcobalamin crosses the blood-brain barrier to protect brain and nerve cells and converts homocysteine to methionine, which is important, as high homocysteine levels have negative impacts on health (more on this later).
  • Cyanocobalamin is a lab-made form, produced by bacterial fermentation; it is the cheapest and most well-studied form to increase B12 levels.
  • Adenosylcobalamin is a natural but unstable form of B12.

B12 is not made by either plants or animals. It is made by bacteria and single-celled microbes. Due to modern sanitization practices, and the chlorine in the water supply, most of this bacteria has been killed off.

Vitamin B12 Deficiency

Prevent Vitamin B12 Deficiency on a Vegan Diet | Soul in the Raw

Even though B12 deficiency can take years to develop, especially if you are just starting out on a vegan diet, the results are devastating. It includes paralysis, psychosis, blindness, and even death. Infants of B12 deficient mothers can develop deficiency even more quickly.

Symptoms of overt B12 deficiency include: fatigue, issues with digestion, loss of appetite, nausea, loss of menstruation, numbness and tingling of hands and feet, nervousness, depression, behavioral changes, paranoia, hyperactive reflex, fever frequent upper respiratory infections, impotence, memory loss, infertility, sore tongue, anemia, low platelet count and increased bleeding, neutropenia, and skin hyperpigmentation.

Due to issues with digestion, absorption, prescription medication such as acid-inhibiting medication, and other health issues, research suggests that a large number of the population is B12 deficient – so it is not just a vegan issue.

How to Prevent B12 Deficiency

The RDA for vitamin B12 is 0.9 mcg for ages 1-3, 1.2 mcg for 4-8, 1.8 mcg for 9-13, and 2.4 for 14 and over. If you are pregnant, you need 2.6 mcg, and if lactating, 2.8 mcg.

A study on UK vegans found a significant vitamin B12 deficiency, resulting in nerve damage and dementia. This study and many others have led to a consensus that B12 supplements are crucial for optimal health.

It is very easy for vegans to achieve a B12 status that is equal to or superior to omnivores.

Adults under 65 should take at least one 2,500 mcg supplement of B12 each week, or a daily dose of 250 mcg. Both doses should come in cyanocobalamin form because there is insufficient evidence that other forms, like methylcobalamin, are effective.

Despite the fact that B12 is water-soluble (overdosing is not so dangerous), you don’t have to take it daily. Through evolution, our bodies have become accustomed to tiny amounts and devised a great way to hold onto it.

You can also supplement through fortified foods. It’s important to break up your dose to 1.5 mcg at a time. If you eat fortified foods three times a day, with 1.5 each, you end up with 4.5 which is exactly what you need.

Note that the daily value on nutrition labels is 5 mcg. As long as a serving contains 25% of daily value, then you can eat a serving of B12 fortified foods at every meal.

However, make sure the foods you choose are not heavily processed, because many fortified foods tend to be.

Like many other nutrients, our ability to absorb vitamin B12 as we age decreases. So if you are over 65, increase your supplementation to 1,000 mcg of cyanocobalamin daily.

Side note if you are already deficient: studies have found that high-dose oral B12 (1,000 mcg every day for two weeks), should raise B12 levels in healthy individuals in a safer and cheaper way than injections

A Note About the Cyanide in Cyanocobalamin

Prevent Vitamin B12 Deficiency on a Vegan Diet | Soul in the Raw

Cyanocobalamin contains a cyanide molecule, which is removed when the cyanocobalamin is used by the body’s cells (note that cyanide is found in many fruits and vegetables, so the body is used to ingesting it; the only exception is people with kidney failure, smokers, and those who eat vegetables like cassava – extremely high in cyanide, so their bodies are saturated with it. In these cases, discuss with your health care professional about supplementing with a different form of B12).

Cyanocobalamin appears in the blood no longer than 5 hours after taking B12. Excess is secreted in the urine.

Plant-Based Eaters with Unhealthy Arteries?!?! Homocysteine and B12 Deficiency

Prevent Vitamin B12 Deficiency on a Vegan Diet | Soul in the Raw

Another sign of mild B12 deficiency is elevated homocysteine levels. Homocysteine is a byproduct of protein (methionine – which comes from animal products) metabolism, and the body can clear it out with the aid of B12.

If you are B12 deficient, homocysteine levels will rise. Keeping homocysteine low is associated with B12 and folate, as well as vitamin B6. Normal blood levels range from 2.2 to 13.2 µmol/l. 10 µmol/l or lower appears not to pose harm.

Elevated homocysteine (a blood level over 14 can double the risk) is an important marker of diseases like cardiovascular disease, Alzheimer’s, and dementia.

Many studies have found consistently that when vegans and vegetarians don’t supplement with B12, their B12 levels drop and their homocysteine becomes elevated higher than omnivores. Vegans who do supplement tend to generally have ideal homocysteine levels.

In just one week of eating a plant-based diet, homocysteine levels drop by 20% – most likely because of the high amounts of fiber in the plant-based diet. However, without B12 supplementation in a plant-based diet, homocysteine in your body will actually rise.

Interestingly, this means that if you do not supplement with B12 on a plant-based diet, you will counteract its benefits! For example, a study found that vegans who don’t supplement with B12 have even thicker and more dysfunctional arteries than omnivores. The moment they started supplementing, they got better.

Risk Factors for Issues Absorbing B12 Supplements

It is important to note that if you have weak stomach acid, you may have an issue with B12 supplement absorption, and here is why.

Firstly, B12 supplements require stomach acid to dissolve the tablets. If your stomach acid is not strong enough, a chewing tablet may be a great replacement.

Secondly, there is the issue of intrinsic factor. B12 cannot survive the stomach’s high acid content so it binds to intrinsic factor to help it pass through the acidic stomach and into the small intestine. When B12 reaches the small intestine, the intrinsic factor dissolves and releases the B12 to bind to a different protein in order to go into the bloodstream and eventually the liver.

When the parietal cells of the stomach, which produce intrinsic factor, are damaged, B12 will not be absorbed.

Alcoholism and ulcerative gastritis, celiac disease, diabetes medications, proton pump inhibitors and other medications, aging, as well as H. pylori and Zollinger-Ellison syndrome and gastric bypass surgery can all cause parietal cell death (which again, you need for the production of intrinsic factor, for the absorption of B12), increasing chances of B12 deficiency.

The absence of intrinsic factor leads to pernicious anemia, which can be passed down in families, especially of Scandinavian or Northern European descent. Grave’s disease, Addison disease, and type 1 diabetes can also increase the risk of pernicious anemia, which can increase the risk of gastric cancer.

In order to overcome this issue, there is evidence that oral supplements will still help, but injections may be needed. This is something best discussed with your healthcare professional.

The Myths about B12-Containing Plant Foods

Prevent Vitamin B12 Deficiency on a Vegan Diet | Soul in the Raw

Currently, there is not a single plant food that can reliably raise B12 levels in humans. Plant foods do not have a B12 requirement to function, and therefore do not have an active mechanism for producing or storing B12. If a plant has B12, it is due to a contamination and is not reliable.

There are rumors that if you allow organic produce to sit at room temperature, bacteria will develop on their surface and produce B12. For this to happen, however, very specific species of bacteria is required as well as cobalt.

There are also rumors that fermented foods contain B12 since fermentation uses bacteria. However, no vitamin B12-producing bacteria is required for fermenting, and if certain fermented foods contain B12, it’s only due to contamination.

Japanese fermented black tea has been shown to raise B12 levels in animals, but not humans. Until this study is replicated on humans, fermented black yea should not be used as a source of B12. Chlorella is also a possible source, but studies about it are inconclusive.

While it is possible that some vegans can escape B12 deficiency via the bacteria in their small intestine, the probability is very low, including for raw vegans, and should not be relied on, especially given the horrific consequences of B12 deficiency.

The Most Accurate Test for B12 Deficiency

Vitamin B12 is a complex vitamin and has a special absorption pathway and many inactive analogs. Inactive analogs are molecules that appear in the blood like active vitamin B12 but are actually not.

Most methods of determining B12 levels do not distinguish between B12 and all the inactive B12 analogs, including seaweeds. Foods and parts of foods may also be contaminated by bacteria, creating B12 analogs, but this does not mean you can rely on any plant foods to get B12.

However, an MMA test will distinguish between “real” B12 and B12 analogs.

Methylmalonic Acid (MMA) is the result of a conversion, for which B12 is the only coenzyme. Thus, MMA levels are the best indicator of a B12 deficiency.

Note that high MMA levels can rarely also be caused by genetic defects, kidney issues, low blood volume, gut bacteria, pregnancy, and thyroid disease.

Normal serum MMA is 0.07 to 0.27 µmol/l. Get your MMA levels tested by urine or blood only after having consumed a B12 supplement for some time. MMA testing is particularly helpful to figure out if you have issues metabolizing B12.

It is important to note that homocysteine and MMA levels may stay low for many years, months and days, and suddenly rise – meaning you’ll suddenly be highly deficient in B12. Therefore, it is crucial not to rely on this short-term test and choose not to take a supplement when you get results that do not demonstrate deficiency, because deficiency may occur shortly after.

Anyone over age 45, or with neurological, psychiatric, or developmental symptoms should be tested for B12 using the MMA urine or blood test (you can predict my choice here, right?) In particular, infants, toddlers, pregnant and breastfeeding women, and anyone over 50 should be tested.

Get the Most Accurate B12 Test Delivered to Your Door

This urinary MMA test is the one I most highly recommend for measuring your B12 levels while taking inactive B12 analogs into account. After you purchase the test, simply take it to a lab closest to you and they will mail it in for you. Easy!

Prevent Vitamin B12 Deficiency on a Vegan Diet | Soul in the Raw

B12 During Pregnancy and for Infants

If you are pregnant and do not get enough B12, then your baby will be deficient too, even if your baby is living off of breast milk. This can result in nerve-related disorders and retarded growth for your baby.

B12 stores in newborns are adequate for the first several weeks only, and after this, they must get it from breast milk or other sources.

If you are currently pregnant, B12 supplementation is crucial because the transport of your own B12 to the fetus can leave you depleted.


And finally, after you have learned all this information, I must end this very serious and long post with a suggestion: unless you want to begin consuming “smoothie bowels” (as Tomer calls them) in place of “smoothie bowls” (since B12 does exist in our colon, but very much downstream), I suggest you start taking your weekly or daily dose of B12 ASAP.


Have any questions about vegan B12? Post them below!

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Marina Yanay-Triner is a wellness coach and recipe developer through Soul in the Raw. Marina creates easy and delicious vegan recipes and writes about the health benefits of a plant-based diet, focusing on evidence-based nutrition information. She loves to help clients go and stick to plant based eating through her powerful coaching program, combining nutrition and cooking education along with transformational mindset work. Marina adopted a whole food, plant based lifestyle over 7 years ago, inspired by her mother's incredible healing story of reversing a crippling bladder disease. She has reversed PMS symptoms and encourage emotional healing from trauma as a result of this transition. Marina is incredibly passionate about the vegan diet for human health, animal welfare, and the well-being of our planet, all of which she envisions as co-dependent.