Can you get B12 from plants?

October 30, 2025 •

4 min read

According to the National Institutes of Health, vitamin B12 is not made by plants and is therefore absent from unfortified plant-based foods. This fact makes understanding whether you can get B12 from plants a critical aspect of maintaining optimal health on a vegan or vegetarian diet.

Quick Summary

Natural plant foods are not a reliable source of vitamin B12, an essential nutrient produced by bacteria. Those on a plant-based diet must obtain it from fortified foods, supplements, or a combination of both to prevent deficiency and ensure proper bodily function.

Key Points

Bacteria, Not Plants: Vitamin B12 is produced by bacteria, not plants, making natural plant foods an unreliable source for humans.
Fortified Foods are Key: Fortified plant-based milks, nutritional yeast, and cereals are dependable sources of B12 for vegans and vegetarians.
Supplements are Most Reliable: Taking a B12 supplement is the most surefire way to ensure adequate intake and prevent deficiency.
Deficiency Risks are Serious: A lack of B12 can lead to serious health problems, including nerve damage, anemia, and an increased risk of cardiovascular disease.
Inconsistent Sources to Avoid: Algae like spirulina and some fermented foods are not reliable sources, as they can contain B12 analogues that do not work in the human body.
Regular Monitoring is Advised: Long-term vegans should consider getting their B12 levels checked regularly to ensure they are meeting their needs.

The Truth About Vitamin B12 and Plants

Vitamin B12, or cobalamin, is an essential nutrient for human health, playing a critical role in nerve function, DNA synthesis, and the formation of red blood cells. Unlike most vitamins, which can be synthesized by plants or acquired directly from the soil, B12 is produced exclusively by certain bacteria and archaea. Animals typically acquire B12 by consuming these bacteria, which accumulate in their flesh, milk, and eggs. Consequently, people who follow a plant-based diet cannot rely on natural, unfortified plant foods for a sufficient supply of B12. Claims that B12 can be reliably obtained from sources like unfortified algae, soil, or fermented foods have not stood up to scientific scrutiny and can contain inactive B12 analogues that do not function in the human body.

Reliable Plant-Based Sources of B12

Since naturally occurring B12 is not present in plant foods, vegans and vegetarians must be proactive in seeking reliable sources. The two most dependable options are fortified foods and supplements. Choosing a combination of both can help ensure consistent and adequate intake.

Fortified Foods: Bridging the Nutritional Gap

Fortified foods have B12 added during processing, offering a convenient way to meet daily requirements. The amount and type of B12 can vary, so it is essential to check product labels. High bioavailability, meaning the body can absorb it easily, is a key benefit of fortified sources.

Fortified Plant-Based Milks: Many soy, almond, oat, and rice milks are fortified with B12. A typical serving may provide a significant portion of your daily needs.
Nutritional Yeast: This deactivated yeast, with its cheesy flavor, is a popular staple in vegan kitchens. It is a highly reliable source of B12 when fortified, with many brands specifically marketing their B12 content.
Breakfast Cereals: Many popular cereals are fortified with B12, offering a simple way to start the day with a boost of this nutrient.
Meat Substitutes: A variety of plant-based meats, such as soy-based burgers and sausages, are now fortified to mimic the nutritional profile of animal products.
Yeast Extracts: Products like Marmite are often fortified with B12 and can be used as a spread or flavor enhancer.

B12 Supplements: The Most Reliable Option

For many, especially those with inconsistent diets or specific health concerns, supplements offer the most reliable and straightforward method of B12 intake. They come in various forms and dosages, and a health professional can help determine the right approach.

Daily Low-Dose: Taking a daily supplement with a small dose (e.g., 10-25 mcg) is a common strategy.
Weekly High-Dose: Some individuals prefer a higher dose once or twice a week (e.g., 1,000-2,000 mcg). This is particularly effective as the body absorbs less B12 at higher doses, making less frequent but larger doses an efficient option.
Sublingual and Sprays: For individuals with absorption issues, sublingual (under the tongue) tablets or oral sprays can be more effective.

Risks of B12 Deficiency

Ignoring B12 intake on a plant-based diet can lead to serious health complications. Since the body stores B12 for several years, symptoms of a deficiency can take a long time to appear, creating a false sense of security. The consequences can be severe, including:

Neurological Damage: Symptoms can include tingling or numbness in the hands and feet, memory problems, and a decline in cognitive function.
Anemia: B12 deficiency can lead to megaloblastic anemia, which causes fatigue, weakness, and loss of appetite.
Cardiovascular Issues: Elevated levels of homocysteine, a byproduct of protein metabolism, are associated with B12 deficiency and an increased risk of heart disease and stroke.

Comparison of B12 Sources

This table outlines the differences between various B12 sources for those on a plant-based diet.


Source	Reliability	Bioavailability	Convenience	Notes
Fortified Foods	High (with consistent intake)	High	Variable	Requires label-checking; intake can fluctuate.
Supplements	Very High	High	Very High	Most reliable method; dosage can be customized.
Unfortified Plant Foods	None	Not applicable	Not applicable	No reliable B12 content for human needs.
Some Algae/Fermented Foods	Very Low	Unreliable	Low	Can contain inactive B12 analogues that interfere with absorption.

Conclusion: Strategic Planning is Crucial for Plant-Based Diets

While the simple answer to 'Can you get B12 from plants?' is no, getting sufficient B12 on a plant-based diet is straightforward and easily achievable with modern food technology and supplementation. By incorporating fortified foods into daily meals and potentially using a supplement, individuals can confidently meet their B12 needs and reap the full benefits of a well-planned plant-based lifestyle. Regular monitoring of B12 levels through a blood test is a smart move for long-term vegans to ensure continued health and peace of mind.

For additional resources and guidance on B12 and other vegan nutrients, consider visiting reputable sources like Vegan Health (VeganHealth.org).

Frequently Asked Questions

Yes, but only if it is specifically fortified with vitamin B12. Most nutritional yeast sold commercially is fortified, but it is always best to check the product label to ensure it contains added B12 and to know the serving size needed.

Some mushrooms, like shiitake, can contain very small amounts of B12. However, the quantity is highly variable and too low to be considered a reliable source for meeting daily B12 requirements. It is not recommended to depend on them for your B12 needs.

Early symptoms can be subtle and include fatigue, weakness, a tingling sensation in the hands and feet, memory problems, and a sore or swollen tongue. Because symptoms develop slowly, a deficiency can go unnoticed for a long time.

Recommendations vary, but The Vegan Society suggests one of three strategies: eating fortified foods two or three times a day to get at least 3 mcg of B12, taking a daily supplement of at least 10 mcg, or a weekly supplement of at least 2,000 mcg.

No, you should not rely on algae like spirulina as a source of B12. While some contain compounds that are chemically similar to B12, these are often inactive analogues that do not function correctly in the human body and can even interfere with B12 absorption.

Yes, the human body can store a significant amount of vitamin B12 in the liver. These stores can last for several years, which is why a deficiency can take a long time to manifest in someone who has recently switched to a plant-based diet. This storage capacity, however, should not be mistaken as a reason to ignore B12 intake.

Cyanocobalamin is the most common and well-researched form of B12 in supplements. It is stable and highly absorbable. Other forms, like methylcobalamin, are also available, but for most people, cyanocobalamin is a reliable and cost-effective choice.