How Much Vitamin B12 Is in Fermented Rice? The Surprising Truth

January 6, 2026 •

4 min read

While some studies have shown that fermenting rice can increase its vitamin B12 content through microbial action, this process is highly variable and not a reliable source. The amount of B12 produced can be inconsistent, making it unsuitable for those relying solely on plant-based foods.

Quick Summary

Fermented rice contains some B12 produced by microbes, but the quantity varies significantly and is not a dependable source. Vegans and vegetarians should use fortified foods or supplements instead.

Key Points

Microbial Synthesis: Vitamin B12 in fermented rice is produced by certain bacteria during the fermentation process, not by the rice itself.
Unreliable Levels: The amount of vitamin B12 in fermented rice is inconsistent and highly variable, depending on the specific microbes and fermentation conditions.
Ineffective Analogues: Some studies have found inactive vitamin B12 analogues in fermented foods, which are not usable by the human body and can interfere with true B12 absorption.
Not for Vegans: Fermented rice should not be relied upon as a primary source of vitamin B12 for vegans and vegetarians.
Proven Alternatives: Reliable B12 sources for plant-based diets include fortified cereals, nutritional yeast, and supplements.
Probiotic Benefits: Despite the unreliable B12 content, fermented rice is a good source of probiotics and improves the bioavailability of other nutrients like iron.

The Allure of Fermented Rice

Fermented rice, known by many regional names such as Panta Bhat or Pakhala, has been a dietary staple in parts of Asia for centuries. Historically, it was cherished for its cooling properties and as a cheap, nutritious meal. In recent years, its reputation has grown, with claims of enhanced nutritional benefits, including increased levels of B-complex vitamins, antioxidants, and probiotics. Among these claims, the potential for vitamin B12 production has drawn significant interest, especially within vegan and vegetarian communities looking for non-animal sources of this critical nutrient. However, the reality of how much, and what kind of, vitamin B12 is in fermented rice is far more complex and uncertain than often reported.

Microbial Synthesis and Its Unpredictable Nature

Vitamin B12, or cobalamin, is naturally produced exclusively by microorganisms like certain bacteria and archaea, not by plants. The presence of B12 in fermented rice is a result of microbial activity, with certain strains of lactic acid bacteria (LAB) being capable of B12 synthesis. Studies have confirmed that when rice is fermented, the microbial action can indeed lead to the production of B12. For example, research on black rice fermented with Saccharomycopsis fibuligera showed measurable B12 levels of 3.68–4.58 μg. This confirms that the potential exists. However, relying on this natural process for a consistent B12 supply is problematic for several reasons:

Strain Specificity: Not all bacteria produce B12. The specific microbial culture present during fermentation is the most crucial factor. Traditional, wild fermentation methods, where the microbes are not controlled, leave the outcome highly unpredictable. An analysis of LAB from traditionally fermented foods found that only a subset of isolates produced B12, and in varying amounts.
Variable Conditions: Environmental factors, such as temperature and fermentation time, also influence the microbial growth and B12 yield. Different batches of fermented rice could have vastly different nutritional profiles, even if prepared by the same person.
Inactive Analogues: A significant concern is the production of pseudovitamin B12, or corrinoid analogues. These compounds are structurally similar to B12 but are biologically inactive in humans. They can even interfere with the absorption of true B12, worsening a deficiency. A study on the fermented food injera found high levels of cobalamin, but it was primarily the inactive form. Without laboratory testing, it's impossible to know if the B12 in your fermented rice is a useful form.

Comparing Fermented Rice with Reliable B12 Sources

To put the B12 content of fermented rice into perspective, it's helpful to compare it with established, reliable sources. The recommended daily intake (RDI) of vitamin B12 for adults is 2.4 micrograms (mcg).


Source	Typical B12 Content (per serving)	Reliability	Notes
Fermented Rice (Studies)	Highly variable, e.g., 3.7-4.6 μg/serving (black rice specific strain); 0 μg in another analysis	Low/Inconsistent	Levels depend on microbes and conditions. Risk of inactive analogues.
Fortified Nutritional Yeast	8.3–24 mcg per ¼ cup	High	Consistent and vegan-friendly source.
Fortified Breakfast Cereal	0.6 mcg per serving (25% DV)	High	Many brands offer a significant percentage of the RDI.
Salmon (cooked)	2.6 mcg per 3 oz	High	Excellent source from an animal product.
Beef (ground)	2.4 mcg per 3 oz	High	Meets the RDI in a small serving.
Vitamin B12 Supplement	Varies widely, often 500-1000 mcg	Highest	Designed for reliable and complete absorption, especially at high doses.

A Safe and Nutritious Approach to Fermented Rice

If you enjoy fermented rice, it's best to appreciate it for its other proven health benefits, rather than relying on it for B12. It's a great source of probiotics that support gut health and digestion. The fermentation process also increases the bioavailability of minerals like iron and reduces anti-nutritional factors like phytates.

How to make basic fermented rice (Panta Bhat):

Start with cooked rice: Use leftover cooked rice from the previous day.
Soak it: Place the rice in a ceramic or earthen pot and add enough water to submerge it fully.
Ferment overnight: Cover the container and let it sit at room temperature for 8-12 hours.
Serve: In the morning, mash the rice slightly and serve with salt and buttermilk, adding onions or chilies for flavor.

Safety note: Because this involves wild fermentation, proper food safety is crucial to prevent the growth of harmful bacteria. Always store at a safe temperature and avoid consuming if it has an off-odor.

Conclusion: Enjoy Fermented Rice, but Get Your B12 Elsewhere

In summary, while fermented rice may contain some vitamin B12 due to microbial action, it is not a dependable or sufficient source to meet daily nutritional needs, especially for those on plant-based diets. The amount and quality of B12 produced are highly inconsistent and unstandardized. For reliable B12 intake, individuals, particularly vegans and vegetarians, should opt for fortified foods or supplements. Fermented rice should be enjoyed for its probiotic benefits and unique flavor, not as a shortcut to vital nutrient intake. For comprehensive information on B12, consult reliable health resources like the NIH Office of Dietary Supplements.

Frequently Asked Questions

Yes, certain microbes, specifically some strains of lactic acid bacteria, can synthesize vitamin B12 during the fermentation process. However, this process is not standardized and relies on the specific bacterial culture present.

No, it is not a reliable source. The amount and bioavailability of B12 produced are inconsistent. Furthermore, there's a risk of producing inactive B12 analogues that the human body cannot use.

There is no typical amount. Studies show highly variable results. Some specific laboratory-controlled fermentations have shown measurable B12, while other analyses have detected negligible amounts.

B12 levels are influenced by the specific microbial strains present, fermentation duration, temperature, and the type of rice used. Wild fermentation, such as overnight soaking, is the most unpredictable.

Yes, fermented rice is a probiotic-rich food that supports gut health and digestion. It also increases the bioavailability of certain minerals, such as iron, and provides B-complex vitamins.

The most reliable sources include fortified cereals, nutritional yeast fortified with B12, fortified plant milks, and vitamin B12 supplements.

Yes, it can. These inactive forms of B12 can compete with active B12 for absorption pathways in the body, potentially worsening a B12 deficiency.

B12 in dairy products is naturally occurring and readily absorbed by the body. B12 in fermented rice is inconsistently produced by microbes, may include inactive forms, and has unpredictable bioavailability.