Does Rice Help Gut Bacteria? The Nuanced Answer

October 5, 2025 •

3 min read

According to a 2024 study, fermenting cooked rice overnight leads to a significant increase in beneficial bacteria like Leuconostoc lactis and Weissella confusa. But beyond fermentation, does rice help gut bacteria? The impact depends largely on the type of rice and how it's prepared, offering a complex answer to a simple question.

Quick Summary

The effect of rice on gut bacteria is not one-size-fits-all. While brown rice is rich in fiber that feeds beneficial microbes, white rice can become a prebiotic source when cooked and cooled. Understanding resistant starch and fermentation reveals how different rice varieties contribute to a healthy gut microbiome.

Key Points

Resistant Starch: Cooling cooked rice, whether brown or white, converts some of its starch into resistant starch, a prebiotic that feeds healthy gut bacteria.
Brown Rice Fiber: As a whole grain, brown rice is rich in dietary fiber that serves as a food source for beneficial microbes, promoting a diverse and healthy gut.
White Rice for Distress: Due to its low fiber content, white rice is easily digestible and is a gentle food option during times of digestive upset.
Fermented Rice: Traditionally fermented rice and rice water act as natural probiotics, introducing beneficial bacteria and enhancing nutrient bioavailability.
SCFA Production: The fermentation of starches and fibers in rice produces short-chain fatty acids (SCFAs), crucial for gut barrier function and reducing inflammation.
Nutrient Comparison: Brown rice offers more fiber, magnesium, and antioxidants, while white rice is often fortified with B vitamins and is easier on sensitive digestive systems.
Preparation Matters: Soaking brown rice can reduce anti-nutrients like phytic acid, while cooking and cooling both rice types increases their gut-friendly resistant starch content.

Understanding Rice's Role in Gut Health

Rice is a staple in diets worldwide, yet its impact on gut health is often misunderstood. The main distinction lies between whole grains, like brown rice, and refined grains, such as white rice. Each interacts with the gut microbiome differently, and the method of preparation can unlock unique benefits.

The Gut-Friendly Power of Resistant Starch

Resistant starch is a key factor in how rice affects your gut. It passes undigested to the large intestine, where gut bacteria ferment it. This fermentation produces beneficial short-chain fatty acids (SCFAs), such as butyrate, acetate, and propionate, which are vital for colon health. Cooking and then cooling rice, especially overnight, increases its resistant starch content. SCFAs produced from this fermentation can reduce inflammation and support the gut barrier.

Brown Rice: The Fiber-Rich Choice

Brown rice, a whole grain, includes the bran and germ, resulting in higher fiber than white rice. This fiber is essential for digestive health, acting as a prebiotic to feed beneficial gut bacteria and support a diverse microbiome. Fermentation of brown rice fiber, particularly by Firmicutes bacteria, increases SCFAs, including butyrate. Brown rice also provides B vitamins, magnesium, and antioxidants found in the bran and germ.

White Rice: An Easily Digestible Option

White rice is less nutrient-dense than brown but is easier to digest due to lower fiber. This makes it suitable during digestive distress like diarrhea or IBS flare-ups. Like brown rice, cooking and cooling white rice significantly increases resistant starch, making leftovers a prebiotic source.

Fermented Rice and Its Probiotic Qualities

Fermenting rice creates probiotics and prebiotics. Traditional practices like soaking cooked rice overnight can produce rice water with beneficial lactic acid bacteria such as Lactobacillus and Lactococcus lactis, acting as natural probiotics. Fermentation also enhances mineral bioavailability, with one study showing a significant increase in iron after 12 hours.

Brown Rice vs. White Rice for Gut Health


Feature	Brown Rice	White Rice
Fiber Content	High (around 3.5g per cup cooked)	Low (around 0.6g per cup cooked)
Resistant Starch	Present, and can be increased by cooling	Can be significantly increased by cooking and cooling
Digestibility	Slower digestion due to higher fiber	Easier to digest, beneficial for sensitive guts
Nutrient Profile	Rich in fiber, magnesium, B vitamins, and antioxidants	Enriched with iron and B vitamins, but lacks the bran and germ nutrients
Best for	Promoting a diverse, thriving microbiome	Periods of digestive distress or acute GI issues
Drawbacks	Higher phytic acid and arsenic potential, though manageable	Can cause blood sugar spikes if not prepared correctly

Which rice is better for gut bacteria?

Brown rice's higher fiber and nutrients make it generally better for consistent gut health, fueling beneficial bacteria. However, cooked and cooled white rice offers prebiotic benefits and is gentler during digestive upset. Including both in a varied diet can be beneficial.

Other factors to consider

Arsenic levels: Brown rice can have more arsenic in its bran. Rinsing and using more water when cooking can help.
Anti-nutrients: Brown rice contains phytic acid, which can hinder mineral absorption. Soaking and cooking can reduce this.

Conclusion

Rice's effect on gut bacteria depends on the type and preparation. Brown rice provides prebiotics from its fiber, while cooled white rice offers resistant starch. Fermented rice preparations are rich in probiotics. By understanding these differences, you can use rice to support your gut microbiome. For more information, visit the National Institutes of Health website.

Frequently Asked Questions

Yes, cooling cooked rice significantly increases its resistant starch content. This resistant starch acts as a prebiotic, feeding beneficial gut bacteria and promoting a healthy gut environment when it reaches the large intestine.

Brown rice is generally better for long-term gut health due to its higher fiber and nutrient content, which feeds beneficial bacteria. However, white rice can be easier to digest and is often recommended for individuals experiencing digestive distress.

Fermented rice water is a natural probiotic, meaning it contains live, beneficial bacteria such as Lactobacillus and Lactococcus lactis. Consuming it adds these good microbes to your gut and improves nutrient availability.

Short-chain fatty acids (SCFAs) like butyrate, acetate, and propionate are produced when gut bacteria ferment resistant starch and fiber. They are a primary energy source for colon cells, reduce inflammation, and support the gut barrier.

Yes, for many people with IBS, white rice can be a suitable option, especially during flare-ups. Its low fiber content makes it less likely to cause bloating or discomfort than high-fiber foods.

Yes, soaking rice before cooking can reduce the levels of anti-nutrients like phytic acid. For brown rice, this is particularly beneficial as phytic acid is concentrated in the bran.

Regular, unfermented rice does not contain probiotics. However, fermented rice preparations, like rice water, develop beneficial probiotic bacteria during the fermentation process.