Nutrition Insights: Does Fermented Rice Have B12?

October 3, 2025 •

6 min read

Fermentation is an age-old process known to enhance nutrients, but a key question for many following plant-based diets is: Does fermented rice have B12? While rice itself contains no Vitamin B12, the fermentation process involving specific microorganisms can lead to the synthesis of this essential nutrient. However, the presence and concentration of B12 are highly variable and depend on the microbial strains and fermentation conditions used.

Quick Summary

Fermented rice can contain Vitamin B12, which is synthesized by microorganisms, not the rice itself. The B12 content is inconsistent in traditional methods but can be significant in controlled fermentations. This makes it a potential source for plant-based diets, but attention to safety and reliability is important.

Key Points

Microbial Synthesis: Fermented rice does contain B12, but it is produced by bacteria during the fermentation process, not the rice itself.
Unreliable Traditional Source: Traditional, uncontrolled fermentation methods result in inconsistent and unreliable B12 content, and carry risks of contamination.
Controlled Fortification: Modern food science can reliably produce significant, bioavailable amounts of B12 by fermenting grains like rice bran with specific, food-safe bacteria.
Beyond B12: Fermented rice offers other significant benefits, including improved gut health from probiotics, and enhanced absorption of minerals like iron and calcium.
Crucial for Plant-Based Diets: For vegans and vegetarians, relying on controlled fermented or fortified products and supplements is the most reliable way to ensure adequate B12 intake.
Bioavailability Consideration: It is important to distinguish true B12 from pseudovitamin B12, an inactive analogue found in some unreliable plant sources.

The Microbial Source of Vitamin B12

Unlike most other vitamins, Vitamin B12, also known as cobalamin, is not produced by plants or animals but is exclusively synthesized by certain types of bacteria and archaea. In animal-based foods, B12 accumulates in tissues because these animals have symbiotic relationships with B12-producing bacteria in their gut. For humans and other non-ruminant animals, the B12-producing bacteria in our large intestine are located too far down the digestive tract for the vitamin to be absorbed effectively. This is why traditional rice is not a source of B12. However, the fermentation process can introduce these B12-producing microorganisms into plant-based foods.

In the context of fermented rice, lactic acid bacteria (LAB) are often involved in the fermentation. Some strains of these bacteria have the capability to synthesize Vitamin B12. For instance, when cooked rice is soaked in water overnight, lactic acid bacteria naturally present in the environment can multiply and ferment the carbohydrates. This microbial activity can enrich the rice with B-complex vitamins, including B12.

Factors Affecting B12 Content in Fermented Rice

The amount of B12 in fermented rice is not guaranteed and can fluctuate widely depending on several factors:

Microbial Strains: The specific bacterial strains present during fermentation are the key. Traditional, uncontrolled fermentation relies on ambient microbes, which may not be effective B12 producers or could introduce contamination. In controlled settings, specific B12-producing microorganisms like Propionibacterium freudenreichii can be used to ensure consistent fortification.
Fermentation Conditions: Factors such as temperature, time, and pH all influence microbial growth and B12 synthesis. Studies have shown that optimizing these conditions can significantly increase B12 yield. For example, a pH range of 6.5-7 has been shown to be favorable for certain B12-producing bacteria.
Hygiene and Contamination: The risk of producing pseudovitamin B12 or introducing harmful bacteria is a major concern with uncontrolled fermentation. Proper food safety and hygiene protocols are essential to mitigate these risks.
Starting Material: The type of rice used can also play a role. Brown rice and rice bran have been shown to be effective substrates for B12 production during fermentation.

Traditional vs. Modern B12 Fortification

Different methods of obtaining B12 from plant-based foods present varying degrees of reliability.


Feature	Traditional Fermented Rice	Modern Fortified Fermented Rice Products
Microorganisms	Ambient, naturally occurring microbes (can be inconsistent).	Cultured, specified B12-producing bacteria like Propionibacterium freudenreichii.
B12 Content	Highly variable and potentially low or insufficient for daily needs.	Significant and nutritionally reliable amounts, can be optimized for high yield.
Bioavailability	Bioavailability is suggested but depends on the specific corrinoids produced.	High bioavailability, with studies showing comparable absorption to other sources.
Safety	Risk of contamination with harmful bacteria exists, making it less safe for vulnerable populations.	Prepared under controlled, sterile conditions to ensure safety and prevent unwanted microbial growth.
Consistency	Inconsistent due to reliance on natural, uncontrolled microbial growth.	Consistent and reliable due to controlled fermentation processes.
Examples	Pakhala, Pazhamkanji.	Fortified cereals or breads using fermented grains.

Health Benefits of Fermented Rice Beyond B12

While the B12 content is a key point, fermented rice offers a number of other health benefits that have long been appreciated in traditional cuisines:

Improved Digestion and Gut Health: The fermentation process produces beneficial probiotics, such as lactic acid bacteria, that help balance the gut microbiome. This can alleviate issues like bloating, constipation, and indigestion. The prebiotics from the rice starch also feed these good gut bacteria.
Enhanced Nutrient Absorption: Fermentation breaks down anti-nutrients like phytic acid, making minerals such as iron, calcium, and magnesium more bioavailable. One study even found that fermenting rice could increase its iron content by a factor of 21.
Natural Electrolyte and Hydrator: Traditional dishes like kanji or torani, which are based on fermented rice water, are rich in minerals and act as natural electrolytes, helping to cool and hydrate the body, especially in hot climates.
Immune System Support: The probiotics and other beneficial compounds produced during fermentation can help strengthen the immune system and protect against infections.

Conclusion: A Nuanced Perspective on Fermented Rice and B12

So, does fermented rice have B12? The answer is yes, but with a significant caveat. The vitamin is not inherent to the rice itself but is a product of microbial activity during fermentation. For traditional preparations, the B12 content is highly variable and unreliable as a primary dietary source, and safety is a valid concern. However, modern, controlled fermentation techniques using specific bacterial cultures can create nutritionally significant and safe levels of B12 in grain-based products. For individuals, particularly vegans and vegetarians, considering fermented rice as a B12 source, understanding the difference between traditional and commercially fortified products is crucial. Relying on fortified foods and supplements remains the most reliable way to ensure adequate B12 intake for those on plant-based diets.

For more detailed information on microbial vitamin production and fortification, consult the National Institutes of Health (NIH) or scientific journals focusing on food science and microbiology.

Note on Traditional Consumption: While modern concerns about food safety exist, it is important to acknowledge the long-standing cultural practice of consuming fermented rice in many parts of the world, where it is valued for its nutritional benefits and cooling properties.

Steps for Preparing Traditional Fermented Rice (Pakhala/Pazhamkanji)

Cook one cup of rice and let it cool completely.
Soak the cooled rice in about two cups of water in an earthen pot or non-metallic vessel.
Cover the vessel and leave it overnight at room temperature for 10-12 hours.
Strain the rice from the water, or mash some of the rice into the water for a thicker consistency.
Add salt to taste and, optionally, a dollop of curd or buttermilk, along with finely chopped green chilies and shallots for flavor.
Consume immediately for a probiotic-rich and refreshing meal.

Different B12 Sources for Plant-Based Diets

Fortified Nutritional Yeast: Contains high levels of B12 and is a popular supplement for vegans.
Fortified Plant Milks and Cereals: Many commercial plant-based milks (e.g., soy, almond) and cereals are fortified with B12.
Mushrooms: Some mushrooms, like dried shiitake, can absorb and contain trace amounts of B12 from bacteria in their growing medium.
Tempeh: Some fermented soybean products, particularly tempeh, can contain a considerable amount of B12 due to bacterial contamination during production, though the amount is not always consistent.
Seaweed (Nori): Dried purple laver (nori) has been identified as a reliable source of bioavailable B12 for vegetarians.
Supplements: B12 supplements are a dependable way to ensure adequate intake, especially for those with restricted diets.

Why Bioavailability Matters

Not all corrinoid compounds that resemble B12 are biologically active in humans. Pseudovitamin B12, for example, is structurally similar but has no vitamin activity. Some food sources, like spirulina and certain algae, are noted for containing pseudovitamin B12, which can even interfere with the absorption of true B12. When considering a food source for B12, it is crucial to ensure it contains the active forms that the human body can utilize, which is why laboratory testing is essential for reliable sources.

The Role of Fermented Grains in Modern Nutrition

The discovery that specific, food-safe bacteria can effectively produce B12 in fermenting grains opens up exciting possibilities for nutritional science. Researchers are exploring ways to use this process to create cost-effective, plant-based B12 sources, such as fortified bread and cereals, that can help combat B12 deficiency in at-risk populations. This approach provides a sustainable and accessible alternative to supplements, aligning with the growing trend towards plant-based eating patterns.

The Importance of B12

Vitamin B12 is essential for numerous bodily functions. It is crucial for the formation of red blood cells, neurological function, and DNA synthesis. A deficiency can lead to serious health problems, including megaloblastic anemia and severe neurological damage. For vegetarians, vegans, and the elderly, who may have difficulty absorbing B12 from animal sources, having reliable plant-based options is vital for long-term health. The potential of fermented foods like rice to be a safe and effective B12 source continues to be a key area of research in nutrition.

Conclusion

In conclusion, fermented rice can produce Vitamin B12 through microbial action, but its reliability and safety vary significantly between traditional and commercially produced versions. While traditional fermented rice preparations offer important probiotic and mineral benefits, they should not be considered a guaranteed source of B12 for a balanced diet. Controlled fermentation processes offer a more promising and consistent approach to B12 fortification in plant-based foods. As interest in plant-based nutrition grows, further research into optimizing these fermentation methods is crucial to create safe and accessible B12 sources for everyone.

Frequently Asked Questions

No, traditional fermented rice is not a reliable source of B12 for vegans. The presence and amount of B12 are inconsistent and can vary widely, making it unsuitable for consistent intake. Reliable sources for vegans include fortified foods and supplements.

Traditional methods rely on naturally occurring microorganisms, which can be inconsistent in their B12 production and potentially unsafe. Commercial methods use controlled fermentation with specific B12-producing bacteria, ensuring a consistent, safe, and reliable B12 content.

Yes, fermented rice water, such as torani, can contain B12. Bacteria that grow during the soaking process produce B12 and other nutrients. However, as with traditional fermented rice, the B12 content is inconsistent and not guaranteed.

Fermentation increases nutritional value by producing probiotics that aid digestion, enhancing the bioavailability of minerals like iron and calcium by breaking down anti-nutrients like phytic acid, and generating beneficial compounds and B-complex vitamins.

Yes, fermented rice contains probiotics and prebiotics that are beneficial for gut health. Regular consumption can help balance gut flora, improve digestion, and reduce issues like bloating and constipation.

A primary risk is the potential for inconsistent B12 levels and the presence of harmful bacteria due to uncontrolled fermentation and hygiene. Food safety concerns, such as the potential for Bacillus cereus contamination, have been noted, though the risk can be managed.

Besides the potential for B12, fermented rice can be a source of other B-complex vitamins, antioxidants, electrolytes, and increased levels of bioavailable minerals like iron and magnesium.