Common Side Effects of Fermented Rice to Be Aware Of

November 5, 2025 •

3 min read

While celebrated for its probiotic benefits, fermented rice can cause side effects for certain individuals. This traditional food can lead to digestive discomfort like gas and bloating, especially when first introduced to the diet. Understanding the potential adverse reactions is crucial for safely enjoying fermented rice as part of a balanced diet.

Quick Summary

Fermented rice, though nutrient-rich, can trigger digestive problems and other adverse reactions in some people. This guide outlines common side effects, who should exercise caution, and best practices for safe consumption.

Key Points

Gas and Bloating: Initial consumption or overindulgence can cause temporary digestive issues due to increased gut bacteria activity.
Histamine Sensitivity: Individuals with histamine intolerance may experience headaches, skin rashes, and digestive upset from biogenic amines.
Immune System Risk: People with compromised immune systems face a rare but serious risk of infection from probiotics.
Food Safety Concerns: Improper preparation can lead to bacterial contamination and food poisoning.
Sodium Content: Some traditional methods or commercial products contain high levels of salt, which is a concern for those on low-sodium diets.
Monitoring Intake: To mitigate adverse effects, it's best to start with small amounts of fermented rice and monitor your body's reaction.

Understanding the Side Effects of Fermented Rice

Fermented rice is a traditional food enjoyed globally, particularly in parts of Asia, and is known for its high probiotic content and enhanced nutritional profile. The fermentation process, often involving soaking cooked rice in water overnight, introduces beneficial microorganisms that improve the bioavailability of nutrients. However, the same microbial activity that provides health benefits can also lead to adverse effects, ranging from mild digestive issues to more significant health concerns for sensitive individuals.

Digestive Discomfort: Gas and Bloating

One of the most common side effects of fermented rice, or any fermented food, is temporary digestive discomfort. This is because the probiotics introduce new strains of bacteria into the gut, which can cause increased gas production as the gut microbiome adjusts.

Initial reaction: When you first start consuming fermented rice, the gut's microflora can undergo a significant shift, leading to a temporary increase in gas and bloating.
Excessive consumption: Overindulging in fermented foods, including fermented rice, can overwhelm the digestive system and lead to persistent bloating and an upset stomach.
Fiber content: If the fermented rice is made from a high-fiber variety like brown rice, the prebiotic fiber feeding the microbes can exacerbate gas and bloating in sensitive individuals.

Histamine Intolerance and Biogenic Amines

Fermented foods, including fermented rice, naturally contain biogenic amines like histamine and tyramine, produced by bacteria during the fermentation process.

Histamine sensitivity: Some people lack sufficient diamine oxidase (DAO), the enzyme that breaks down histamine. For these individuals, consuming histamine-rich foods can lead to various allergic-like reactions.
Symptoms of intolerance: These reactions can include headaches, migraines, skin rashes, itching, flushing, a runny nose, hives, and gastrointestinal symptoms like diarrhea.
Central nervous system effects: Amines can also stimulate the central nervous system, potentially affecting blood flow and triggering headaches or migraines in susceptible people.

Risks for Compromised Immune Systems

While probiotics are beneficial for most, they can pose a risk for individuals with severely compromised immune systems.

Vulnerable populations: People with conditions like HIV/AIDS, cancer patients undergoing chemotherapy, and organ transplant recipients have weakened defenses against infection.
Increased infection risk: In rare cases, the probiotics from fermented foods can cause infections in these high-risk individuals, leading to more serious systemic issues like sepsis.

Potential for Food-Borne Illness

Improperly prepared or stored fermented rice can become contaminated with harmful bacteria, leading to food poisoning.

Unsanitary conditions: Failure to maintain proper food safety standards, such as using unsterile equipment or incorrect temperatures, can allow dangerous pathogens to grow.
Bacterial toxins: In some cases, harmful bacteria can secrete toxins that can lead to foodborne illness, even if the probiotics are also present.

Fermented Rice Safety: Store-Bought vs. Homemade


Feature	Store-Bought Fermented Rice	Homemade Fermented Rice
Control	Less control over fermentation process and ingredients.	Complete control over ingredients, hygiene, and fermentation time.
Risk of Contamination	Lower risk due to controlled, sterilized production environments.	Higher risk if proper food safety practices are not followed.
Ingredients	Often contain added sugars or sodium for flavor and preservation.	Allows for minimal or no added salt and sugar.
Nutrient Consistency	Standardized nutritional profile, but potentially lower probiotic diversity.	Variable nutrient content depending on the fermentation method and duration.
Histamine Levels	May have high, but generally consistent, levels of biogenic amines.	Histamine levels can vary unpredictably based on fermentation conditions.
Convenience	Ready-to-eat with no preparation time.	Requires time and effort for preparation and monitoring.

Conclusion

Fermented rice is a nutrient-dense food with many potential health benefits, but it is not without its side effects. For most people, any initial digestive discomfort from the probiotic influx is temporary and resolves as the body adjusts. However, individuals with histamine intolerance, compromised immune systems, or specific gastrointestinal issues should exercise caution. Adhering to proper food safety practices is essential, especially when preparing fermented rice at home, to prevent the risk of foodborne illness. By understanding the potential downsides and listening to your body's signals, you can decide if and how to incorporate this traditional food into your diet safely and beneficially.

For further exploration:

For more information on the safety and health aspects of fermented foods, you can refer to the BC Centre for Disease Control's Fermented Foods Safety Guidance.

Frequently Asked Questions

Yes, if fermented rice is not prepared with proper hygiene or stored correctly, it can become contaminated with harmful bacteria, leading to foodborne illness.

Fermented rice is rich in probiotics, which are beneficial bacteria. When you consume it, these microbes interact with your gut flora, which can produce excess gas and cause temporary bloating.

Individuals with histamine intolerance, compromised immune systems, or certain digestive disorders like SIBO should be cautious or avoid fermented rice. Pregnant women and infants should also exercise caution.

Biogenic amines, including histamine and tyramine, are natural compounds in fermented foods. For people with sensitivity or intolerance, these amines can trigger headaches, migraines, and allergic reactions.

Mild, temporary bloating is a normal sign that your gut is adjusting to the new probiotics. However, if symptoms are severe, persistent, or painful, it could indicate a more serious issue or a sensitivity.

Yes, headaches and migraines can be a side effect, particularly for people with histamine intolerance. The biogenic amines in the fermented rice can stimulate the central nervous system and trigger these symptoms.

Homemade fermented rice carries a higher risk of contamination if not prepared hygienically. Store-bought versions might contain more additives like salt or sugar, which can cause other issues, but are typically safer from harmful bacteria.