What Herb is High in Vitamin B12? The Surprising Truth

December 27, 2025 •

3 min read

Vitamin B12 is crucial for nerve function and red blood cell production, but unlike most vitamins, it is not produced by plants. This leads to a persistent nutritional myth: finding a true herb high in vitamin B12 is impossible without fortification or microbial contamination.

Quick Summary

Vitamin B12 is almost exclusively found in animal products and requires supplementation for plant-based diets. Despite some claims, no herb contains bioavailable B12 naturally, with unreliable amounts found only in certain fermented foods, algae, and mushrooms due to microbial activity.

Key Points

Plants Do Not Produce B12: Vitamin B12 is synthesized exclusively by certain microorganisms, not by any herb or plant.
Natural Herbs Are Not Reliable: While some claim certain herbs or mushrooms contain B12, the levels are inconsistent, low, and often due to bacterial contamination.
Inactive B12 Analogues Are a Risk: Some plant sources, like spirulina, contain inactive B12 analogues that can interfere with absorption and worsen a deficiency.
Fortified Foods are Dependable: The most reliable vegan food sources are fortified products, including nutritional yeast, cereals, and plant-based milks.
Supplements are Safe and Effective: For those on a vegan diet, B12 supplementation is recommended by health professionals and is a safe, effective way to meet daily needs.
Deficiency Poses Serious Health Risks: Long-term B12 deficiency can lead to anemia and irreversible neurological damage, emphasizing the need for reliable sources.

The Fundamental Myth: Why Plants Don't Produce Vitamin B12

Contrary to a common misconception, plants do not synthesize vitamin B12. This essential nutrient is created exclusively by microorganisms, such as bacteria and archaea. Animals, particularly herbivores, acquire B12 by ingesting these bacteria from soil and grass or from bacteria within their own digestive systems. This is why animal products have traditionally been the primary dietary source for humans. While claims about certain herbs or plants containing B12 persist, scientific consensus confirms these are not reliable sources.

The Role of Microbes in Plant-Based B12

Some plant-based foods appear to contain B12, but this is always the result of a symbiotic relationship with bacteria or contamination. For example, certain algae like Chlorella and purple laver (nori) contain B12 because they have associated B12-producing microbes. Similarly, some fermented products like tempeh may contain B12 due to bacterial activity during fermentation, but the levels are inconsistent and unreliable. Modern hygiene and food processing further reduce the chances of acquiring B12 through accidental microbial consumption from fresh produce.

Unreliable Plant-Derived Sources Often Cited

Several sources are frequently cited for plant-based B12, but their effectiveness is limited or unproven.

Shiitake Mushrooms: Dried shiitake mushrooms contain a type of B12, but the amount is highly variable and often low. Relying on them alone to meet daily needs would require consuming large, impractical quantities.
Algae (Nori, Spirulina): Dried purple laver (nori), used for sushi, contains a substantial amount of B12 from bacteria. However, some algae, including spirulina, contain inactive B12 analogues that can interfere with the absorption of true B12 and worsen a deficiency. For this reason, nori is not considered a sole reliable source.
Fermented Foods: Certain fermented products like tempeh can contain some B12 due to contamination during production, but this is not guaranteed. Commercially produced fermented foods, especially in Western countries, should not be relied upon for consistent B12 levels.

Reliable Vegan Sources: Fortification and Supplements

For those on a plant-based diet, the only dependable sources of B12 are fortified foods and dietary supplements. This is the recommendation of major health organizations like the Academy of Nutrition and Dietetics. Fortified products ensure a consistent and bioavailable supply of the vitamin.

Comparison of B12 Sources


Source	Type of B12	Bioavailability	Reliability for Vegans	Daily Intake Requirements
Animal Products	Naturally Occurring (Methylcobalamin, Adenosylcobalamin)	High	Not for Vegans	Met through consumption of meat, dairy, eggs
Fortified Foods (Yeast, Cereals)	Cyanocobalamin	High and Consistent	High	Check food labels; one tablespoon of fortified nutritional yeast provides 100% DV
Supplements	Cyanocobalamin or Methylcobalamin	High and Consistent	High	Dosage depends on factors like age and diet; consult a professional
Fermented Foods (Tempeh)	Inconsistent/Bacterial Contamination	Variable	Very Low	Unreliable for meeting daily needs
Algae (Nori, Chlorella)	Can be active, but variable	Variable	Low	Nori has active B12, but levels fluctuate significantly; Chlorella shows potential but needs more study

The Risks of Inactive B12 Analogues

An often-overlooked danger of relying on certain purported plant sources like spirulina is the presence of inactive B12 analogues, sometimes called pseudovitamin B12. These compounds are structurally similar to true B12 but are not biologically active in humans. Worse, they can interfere with the body's absorption and use of the active form of B12, effectively making a deficiency more severe. This is a key reason why experts advise against relying on untested natural sources.

Conclusion: How to Get Enough Vitamin B12

The notion of a herb being high in vitamin B12 is a popular myth that science and nutrition research have consistently debunked. For those following a plant-based diet, relying on any herb for a natural and reliable source of B12 is an unwise nutritional strategy. Instead, the most effective and safe approach is to consume B12-fortified foods, such as nutritional yeast, plant-based milks, and breakfast cereals. Dietary supplements are also a highly effective and reliable option. Individuals should consult with a healthcare professional or registered dietitian to ensure they are meeting their specific B12 requirements, especially since deficiency can lead to serious neurological issues. A well-planned plant-based diet is nutritionally adequate, but it must include a proven, reliable source of this vital nutrient.

Frequently Asked Questions

No, it is not possible to obtain sufficient vitamin B12 from herbs alone. Plants and herbs do not produce this vitamin, and any trace amounts found are from microbial contamination and are not a reliable source.

Nutritional yeast is not an herb. It is a microorganism (a fungus) that is often fortified with vitamin B12 during production, making it a reliable and effective source for those on a plant-based diet.

While dried shiitake mushrooms may contain a form of vitamin B12, the amount is often too low and inconsistent to be considered a reliable source for meeting daily requirements.

The B12 content in fermented foods like tempeh depends on bacterial contamination during the fermentation process. Because this is not controlled, the amount of bioavailable B12 is highly inconsistent and therefore unreliable.

It depends on your overall diet and the amount of fortified foods you consume. For many on a plant-based diet, a supplement provides extra security to ensure adequate intake. Regular check-ups with a doctor are recommended.

Inactive B12 analogues are compounds found in some foods, like spirulina, that are structurally similar to B12 but have no biological activity in humans. They are problematic because they can block the absorption of active B12, worsening a deficiency.

Vegans, strict vegetarians, and older adults are most at risk of B12 deficiency. Vegans consume no animal products, the natural source, while older adults often have reduced absorption abilities.