Where do vegans get vitamin B12? Are vegan B12 sources as good as animal-based B12 sources? Vitamin B12 is one of the most complex and subsequently one of the most misunderstood essential nutrients, making it the subject of many heated debates.

Eating a plant-based, vegan diet is extremely healthy and provides an abundance of every single amino acid, mineral, and vitamin — except one: vitamin B12.

Your body uses vitamin B12 to help make DNA, nerve cells, and blood cells. You need B12 for proper nervous system and brain function.⁽¹⁾

Vitamin B12 deficiency is serious and can cause anemia, fatigue, nerve damage, digestive issues, neurological changes like depression and memory loss, paralysis, and even death.⁽¹⁾

Vitamin B12 deficiencies among vegans are very common⁽²⁾ but are also common among meat-eaters,⁽³⁾ especially among older adults; people with genetic markers which hinder B12 absorption; people taking certain medications such as proton pump inhibitors; and people with digestive disorders causing difficulty in absorbing nutrients from food.^{(4, 5)}

The good news is that getting enough vitamin B12 is actually extremely easy, even on a vegan diet. You just have to be responsible about it.

Where Does Vitamin B12 Come From?

It’s well-known that animal products are the only widely-available natural dietary source of B12 available to humans in the Western world, but contrary to what many believe, vitamin B12 isn’t created by animals. 

Vitamin B12 is actually created by certain micro-organisms such as bacteria that naturally live in the soil and digestive systems of animals.⁽¹⁾ Specifically, these bacteria are Propionibacterium shermanii and Pseudomonas denitrificans.

Vitamin B12, or cobalamin, contains the mineral cobalt and exists in several forms. Collectively, these B12 compounds are known as “cobalamins.” Bacteria use cobalt in order to synthesize B12. No cobalt = no cobalamins.

Can I Get B12 From Plants?

For much of history, humans could get B12 from bacteria living on the surfaces of foods they would eat.⁽⁶⁾

In modern society, we have the advanced hygiene techniques of modern industrialized farming, which have made it impossible to get adequate amounts of B12 from plant foods alone.

On top of this, most of us are careful to wash and cook the foods we eat, often completely eliminating any vitamin B12 content which may have been present on the surface of those foods.

Can I Get B12 From Algae, Seaweed, Spirulina, Mushrooms, Duckweed, etc?

The jury is still out whether sources other than bacteria cultures, such as algae, seaweed, Spirulina, mushrooms, tempeh, duckweed, and other plant-based foods can be relied upon as primary sources of B12 for vegans.⁽⁷⁾

Until conclusive evidence proving these alternatives raise B12 levels enough to be adequate on their own, they shouldn’t be considered a reliable source of B12.

The science today indicates that only bacteria cultures can be counted on for supplying vegans with adequate amounts of active B12 via supplements and fortified foods.⁽⁷⁾

How Long Can Vegans Live on B12 Reserves?

Vegans can live on B12 reserves for a remarkably long time before developing a B12 deficiency and even longer before showing symptoms of deficiency.

Your liver can store up to 2,000-3,000 mcg of B12, which might not sound like much, but your body only needs about 3 mcg (or about 0.1%) of this to be released every day in order to function properly.⁽⁵⁾

Absorption of B12 increases during periods of low-intake, which can delay vitamin B12 deficiency for up to 20-30 years. 

Types of Vitamin B12

There are currently four forms of vitamin B12,⁽⁹⁾ which can make things confusing when reading the label of a B12 supplement or trying to figure out which form is best for you.

All four forms of B12 have a cobalamin molecule at their center with a side group attached. The side group is where the differences come in.

The 4 forms of B12 are:

• Methylcobalamin
• Adenosylcobalamin
• Hydroxocobalamin
• Cyanocobalamin

Methylcobalamin & Adenosylcobalamin

Methylcobalamin and adenosylcobalamin are naturally-occurring forms of B12. These coenzymes are what all other forms of B12 must be converted into by your body.

Methylcobalamin and adenosylcobalamin are naturally found in animal products. You can also find them in supplements and shots, though they’re usually more expensive and harder to find.

Hydroxocobalamin

Hydroxocobalamin is another naturally-occurring form of B12. To use it, your body has to convert it into the active forms of B12 (methylcobalamin and adenosylcobalamin).

Like methylcobalamin and adenosylcobalamin, hydroxocobalamin is also naturally found in animal products. It’s the most common form of B12 found in B12 shots and isn’t typically found in other B12 supplements because its hydroxyl side group has the least attraction to the cobalamin molecule, making it the least stable form of B12.

Hydroxocobalamin is best for people who have difficulty absorbing B12 from other sources.⁽¹⁾

Cyanocobalamin

Cyanocobalamin is a synthetic form of B12. To use it, your body has to convert it into the active forms of B12 (methylcobalamin and adenosylcobalamin).⁽¹⁾

Cyanocobalamin is the most common form of B12 used in supplements and fortified foods⁽¹⁾ because its cyanide molecule has the most attraction to the cobalamin molecule, making it the most stable form of B12.

Some people question the safety of cyanocobalamin because cyanide is a component of cyanocobalamin and has to be removed from the cobalamin it’s attached to when your body uses it. Rest assured, many fruits and vegetables naturally contain similarly insignificant amounts of cyanide and cyanocobalamin is considered to be just as safe.

However, people with kidney problems should avoid taking cyanocobalamin because their bodies aren’t able to detoxify and eliminate the cyanide molecules in this type of B12 as easily and efficiently as people with normally-functioning kidneys.

Daily Recommendations

Nutritional recommendations for vitamin B12 and other nutrients are developed by the National Academy of Medicine (formerly the Institute of Medicine) to plan and assess the nutrient intakes of healthy people.

Recommended Daily Allowance (RDA) for Vitamin B12:

Recommended Dietary Allowance (RDA): average daily intake of a nutrient that’s sufficient to meet the nutrient requirements of nearly all (97%–98%) healthy people.
Adequate Intake (AI): approximate intake assumed to be nutritionally adequate based on limited research, though still not enough evidence to develop an RDA.
Tolerable Upper Intake Level (UL): maximum daily intake that’s unlikely to cause adverse health effects.

No upper limits have been set for vitamin B12 intakes because no toxic effects have been identified.⁽¹⁾

Some people may need more B12, such as people who genetically cannot absorb B12 through food, people who are pregnant, or elderly people.^{(1, 3, 4)}

Best Vegan Sources of Vitamin B12

The only significant sources of vegan vitamin B12 are supplements and fortified foods.⁽¹⁾

Vitamin B12 itself is vegan and when found in supplements or fortified vegan foods is sourced from bacteria cultures — not animals — however, some companies will add gelatin to supplements, so you should always read labels.

Vegan B12-Fortified Foods

Some common B12-fortified vegan foods include:

• Fortified non-dairy milk
• Fortified breakfast cereal
• Fortified meat substitutes
• Fortified nutritional yeast

Both brewer’s yeast and nutritional yeast don’t contain B12 unless they’re fortified with it. Currently, there’s only one fortified nutritional yeast on the market, Red Star Vegetarian Support Formula.

Vegan B12 Supplements

The most effective way to take B12 supplements varies from person to person.⁽¹⁾

The most common types of vitamin B12 supplements are:

• Pill
• Lozenge
• Liquid
• Nasal gel
• Shot

Most people will be able to prevent B12 deficiency with a daily or weekly dose of pills, lozenges, liquids, or nasal sprays. These supplements are usually sold over-the-counter and are comparable as far as absorption and effectiveness are concerned.⁽¹⁾

Vitamin B12 shots are available by prescription only and are administered by a healthcare professional. They’re generally for people with conditions that interfere with their body being able to absorb B12 from food or over-the-counter supplements, such as people who can’t produce intrinsic factor (a protein that helps B12 get to the small intestine where it’s absorbed).⁽¹⁾

How To Absorb More Vitamin B12 on a Vegan Diet

Most B12 dosage absorption tests are carried out using cyanocobalamin, so you should apply dosage recommendations to cyanocobalamin and adjust accordingly for other B12 forms.

The way your body absorbs B12 isn’t straightforward. Generally, the more B12 you consume at one time, the less of it you actually absorb.^{(1, 10)}

For instance, you can absorb between 50-80% of a 1 mcg dose, but your body needs 2.4 mcg per day, which means you have to take a higher dose to avoid deficiency. But if you double that dose to 2 mcg, now you’re only absorbing 40-50%. 

Absorption rates really nosedive after about 5 mcg and doses above 25 mcg are absorbed at a rate of 5% and under.

Vegan B12 Fortified Foods

In order for your body to absorb enough vitamin B12 from fortified foods it’s recommended to eat fortified foods in a particular way:

• At least 3 servings per day
• Each serving must contain at least 25% of the RDA (found on ingredients list)
• Each serving must be eaten at least 4-6 hours apart

For most people, supplements are a much simpler and more reliable option.

Vegan B12 Supplements

Vitamin B12 supplements are generally more effective when consumed with other B vitamins, especially vitamins B6 (pyridoxine) and B9 (folate). These are called B-complex supplements.

The sweet-spot for cyanocobalamin doses, depending on frequency:

• Daily: ~100 mcg taken = ~2-3 mcg absorbed
• Bi-weekly: ~1,000 mcg taken = ~12.5 mcg absorbed
• Weekly: ~2,000 mcg taken = ~25 mcg absorbed

Because there is no known upper-limit to the amount of B12 we can safely consume, taking a B12 supplement with occasional fortified foods is fine, however, taking above 5,000 mcg per week should be avoided despite the lack of evidence for toxicity from higher amounts.

“Vegan B12 Supplements Aren’t Natural!”

Some ill-informed meat-eaters and paleo cave-dwellers insist that taking a vitamin B12 supplement is ‘unnatural,’ therefore ‘proving’ that veganism itself is unnatural and that vegans should eat more meat.

As already outlined, modern farming practices (which are unnatural themselves) are what have made plant foods become an unreliable source of B12-containing bacteria for humans. Because of this, getting enough B12 can be a challenge for pretty much everyone, whether they’re vegan or not.^{(2, 3, 4)}

Farm Animals Are Given B12 Supplements

This may be surprising to you, but it’s very common for farmers to give B12 supplements to animals in the meat, dairy, and egg industries. So, whether meat-eaters like it or not, they’re already consuming B12 supplements second-hand.

Ruminants

Ruminants are grazing animals (such as cattle, goats, and sheep) that have B12-producing bacteria living in their stomach. Their stomachs contain multiple compartments which helps them to digest their natural diet of grasses. Because the small intestine follows the stomach in the digestive system and B12 is absorbed in the small intestine, ruminants are able to use the B12 made by the bacteria in their stomach.

The bacteria in their stomach need cobalt to produce B12. Cobalt is found in the soil in many parts of the world, but because of modern farming practices very little of it makes its way into livestock feed, making cobalt supplements often necessary.⁽¹¹⁾

Ruminants who eat a diet of grains instead of grasses still often require B12 supplements. Even “grass-fed” animals are usually fed a grain and corn diet in the months before slaughter to fatten them up in a process called “finishing” and receive B12 supplements during that time.⁽¹²⁾

Non-Ruminants

Like humans, non-ruminants like pigs, chickens, and turkeys, have a stomach with only one compartment and don’t have B12-producing bacteria in their stomachs like ruminants do.

Because non-ruminants are typically fed a diet of grains, soy, and other plant foods (which are currently not a significant source of B12 due to modern agriculture), they often need B12 supplements so they don’t become deficient.

Antibiotics

99% of all livestock animals on the planet currently live and die on factory farms, also known as CAFO’s (concentrated animal feeding operations).⁽¹³⁾

These animals live in extremely cramped and filthy conditions, which is a breeding-ground for the bad kinds of bacteria that cause disease. Farmers combat this by pumping livestock with antibiotics. Unfortunately, this also kills the good bacteria that help create vitamin B12, so supplements are often necessary and unavoidable.

Disclaimer: The contents of this website are for educational purposes and are not intended to offer personal medical advice. To make sure your diet is providing you with the correct amount of nutrients your body needs, be sure to consult a nutrition specialist (ie: registered dietitian) with expertise in vegan diets.

Related:

• Vegan Nutrition 101
• Vegan Protein Sources
• Vegan Folate Sources (Coming soon!)
• Vegan-Friendly Food From Around the World