Does Alfalfa Have Vitamin B12? Separating Fact from Fiction

November 15, 2025 •

4 min read

According to extensive scientific research, vitamin B12 is synthesized exclusively by certain bacteria and archaea, not by plants like alfalfa. This foundational fact is crucial for anyone asking: does alfalfa have vitamin B12, and can it meet my nutritional needs?

Quick Summary

Alfalfa and other plants do not naturally produce vitamin B12. Any trace amounts found are typically inactive pseudovitamin B12 from bacterial contamination, making them an unreliable source for humans. Individuals following a plant-based diet should not depend on alfalfa for this vital nutrient.

Key Points

Microbial Origin: Vitamin B12 is produced exclusively by bacteria and archaea, not by plants like alfalfa.
Pseudovitamin B12: Alfalfa may contain inactive analogues of B12 (pseudovitamin B12) from bacterial contamination, which are unusable by the human body.
Risk of Interference: Pseudovitamin B12 can compete with true vitamin B12 for absorption, potentially worsening a deficiency.
Alfalfa Sprouts: Levels of B12 in alfalfa sprouts are variable and insufficient for daily requirements, making them an unreliable source.
Reliable Vegan Sources: The safest and most dependable vegan sources of B12 are fortified foods and dietary supplements.
Not Nutritious for B12: Despite containing other valuable nutrients like vitamins K and C, alfalfa should not be depended on for vitamin B12.

Why Plants Don't Produce Vitamin B12

At the core of the question, "Does alfalfa have vitamin B12?" is a fundamental biological reality: plants do not produce vitamin B12 (cobalamin). This essential vitamin is the exclusive domain of specific microorganisms, such as bacteria and archaea. Herbivorous animals, like cattle, acquire B12 through symbiotic relationships with the bacteria residing in their stomachs. Humans, in turn, traditionally obtained B12 by consuming animal products where the vitamin has been concentrated. This microbial origin explains why relying on plant-based foods, including alfalfa, for vitamin B12 is often a misunderstanding.

The Problem with Pseudovitamin B12

The confusion surrounding plant sources often arises from the presence of "pseudovitamin B12," which are corrinoid compounds that resemble active vitamin B12 but are biologically inactive in humans. Testing methods used in the past sometimes failed to distinguish between true vitamin B12 and its inactive analogues, leading to inaccurate conclusions. For example, studies on algae like spirulina and some fermented products have revealed that they contain large amounts of these inactive analogues. The implications of this are significant:

Misleading Test Results: Traditional serum tests for B12 may show seemingly normal levels, even when a deficiency is present, if a person consumes foods high in pseudovitamin B12.
Absorption Interference: Inactive analogues can compete with and block the absorption of the small amount of true vitamin B12 in the body by binding to transport molecules like intrinsic factor.
Unreliable Sources: The ratio of active B12 to inactive analogues in plants and fermented foods varies drastically based on microbial interaction, making them unreliable for meeting daily requirements.

Alfalfa Sprouts and B12

Alfalfa sprouts are often touted as a possible source of vitamin B12. While it's true that certain bacteria present during the sprouting process can produce a small amount of B12, the quantity is highly variable and insufficient to meet daily needs. One study even found that alfalfa sprouts contained zero vitamin B12. Relying on alfalfa sprouts for B12 is a risky strategy for vegans and vegetarians. Furthermore, sprouts carry a risk of bacterial contamination, highlighting the importance of sourcing from reputable producers and practicing food safety.

Alfalfa's Nutritional Profile Beyond B12

Despite not being a reliable B12 source, alfalfa offers a host of other beneficial nutrients. It is a rich source of vitamins A, C, E, and K. It also contains several minerals, including calcium, potassium, phosphorus, iron, and magnesium. Alfalfa sprouts, in particular, provide antioxidants and other phytonutrients. It's a nutritious plant, just not for its supposed B12 content.

Alfalfa vs. Reliable Vegan B12 Sources

The following table compares alfalfa to proven vegan B12 sources to illustrate why supplementation is necessary for those on plant-based diets.

How to Ensure Adequate Vitamin B12 Intake

For those on a vegan or plant-based diet, relying on chance microbial interaction is not an option. Prevention of vitamin B12 deficiency through supplementation offers an effective, economical, and sustainable way to avoid adverse health consequences.

Consume Fortified Foods: Incorporate B12-fortified products into your daily diet, such as breakfast cereals, plant-based milks, and nutritional yeast.
Take a Supplement: The Vegan Society recommends that vegans take a reliable B12 supplement, either a single dose daily or a higher dose a couple of times a week, to meet requirements effectively.
Check Labels: Be vigilant and check the nutrition labels of any vegan products you consume to ensure they are adequately fortified with vitamin B12.
Consult a Healthcare Professional: Anyone transitioning to a plant-based diet or concerned about their B12 levels should speak with a doctor or registered dietitian to monitor their status through blood tests.

For a deeper dive into the origin of B12, see the comprehensive review on vitamin B12 sources and microbial interaction from the National Institutes of Health(https://pmc.ncbi.nlm.nih.gov/articles/PMC5788147/).

Conclusion: The Unreliable B12 Source

In conclusion, alfalfa does not naturally contain active vitamin B12 that is reliable for human nutrition. The presence of any B12-like compounds in alfalfa is a result of bacterial activity and is often composed of inactive pseudovitamin B12, which can even interfere with the absorption of true B12. For individuals on plant-based diets, relying on alfalfa, whether as a whole plant or in sprouts, to meet their B12 needs is a mistake. The only reliable strategy is to incorporate fortified foods or a dedicated B12 supplement to ensure adequate intake and support long-term health.

Frequently Asked Questions

No. While some bacteria on unwashed sprouts might produce trace amounts of B12, this is not a reliable or safe method to meet human nutritional needs. The amount is inconsistent and there is a risk of harmful bacterial contamination.

Distinguishing between the two is crucial because pseudovitamin B12 is inactive in humans and can interfere with the absorption of true vitamin B12. Consuming analogues can mask a deficiency and hinder proper nutrient intake.

No plant-based foods can be relied on to provide consistent and sufficient amounts of active B12 without fortification. Reliable vegan sources are fortified products like cereals, plant milks, and nutritional yeast, along with supplements.

Yes. Since B12 is not produced by plants, any diet that eliminates animal products will not provide a reliable source of this vitamin. Therefore, all vegans and many vegetarians should supplement or consume fortified foods.

A deficiency in vitamin B12 can lead to serious health problems, including megaloblastic anemia, nerve damage, fatigue, cognitive issues, and impaired brain function.

The most reliable way to assess B12 status is through advanced blood tests, such as a methylmalonic acid (MMA) test, which measures B12 activity rather than just levels, which can be inflated by inactive analogues.

Alfalfa is a good source of several other nutrients, including vitamins A, C, E, and K, as well as minerals like calcium, iron, and magnesium. It is also known for its antioxidant and anti-inflammatory properties.