Lactobacillus reuteri is a beneficial bacteria, often referred to as a probiotic, that naturally inhabits the human body. This microorganism contributes to maintaining a balanced internal environment, influencing various bodily functions.
Understanding Lactobacillus reuteri
Lactobacillus reuteri is a probiotic bacterium, recently reclassified as Limosilactobacillus reuteri in April 2020. Despite this, its original name is still widely used. It is a gram-positive, rod-shaped bacterium that produces lactic acid. This bacterium naturally resides in various parts of the human body, including the gastrointestinal tract, urinary tract, and skin. It is also found in breast milk, suggesting transmission from mother to infant. Beyond humans, L. reuteri is common in the gastrointestinal tracts of many other mammals and birds. While it can be found in some fermented foods, such as certain yogurts and cheeses, its presence and specific strains can vary.
Mechanisms of Action
L. reuteri acts through several biological mechanisms. One involves producing antimicrobial substances, notably reuterin. Reuterin is a broad-spectrum compound that inhibits the growth of harmful bacteria, fungi, and protozoa by disrupting their cellular processes.
The bacterium also modulates the immune system. It influences immune cells like dendritic cells, macrophages, and T-cells, promoting an anti-inflammatory response. Some L. reuteri strains can reduce pro-inflammatory cytokines while increasing anti-inflammatory ones, such as IL-10, and promote regulatory T cell development. This immunomodulation prevents excessive inflammation and supports overall immune function.
L. reuteri also strengthens the gut barrier. It stimulates mucus production, forming a protective layer over the epithelial cells lining the gastrointestinal tract. This mucus layer, along with the bacterium’s ability to adhere to the intestinal mucosa, helps prevent pathogens from attaching and invading, reinforcing the gut’s defense mechanisms.
Key Health Benefits
L. reuteri has demonstrated positive effects in several health areas, particularly digestive and oral health. In digestive health, it reduces excessive crying in infants with colic, with studies showing a significant reduction in crying time for breastfed infants. It also helps manage various forms of diarrhea, slightly reducing its duration in children. This probiotic may alleviate symptoms of stomach pain and constipation in children. While its role in adults is less clear, some research suggests benefits for functional abdominal pain.
L. reuteri can also reduce the side effects of standard therapies for Helicobacter pylori infection, which can lead to ulcers. Beyond digestive issues, L. reuteri contributes to oral health by inhibiting harmful oral bacteria that cause plaque and gingivitis. It has also been explored for improving bad breath. Emerging research suggests broader impacts, including a modest reduction in high cholesterol levels.
Sources and Usage
L. reuteri can be found naturally in certain fermented foods, though specific strains and quantities vary significantly. Some yogurts and cheeses may contain L. reuteri, with certain “superfood” yogurts specifically enriched. Sourdough bread, kimchi, and miso are also sometimes mentioned as sources, but adequate amounts of live L. reuteri are not guaranteed in all fermented products.
The most reliable way to ensure targeted intake is through dietary supplements. These are widely available in various forms, including capsules, tablets, and drops, especially for infants. When choosing a supplement, strain specificity is important, as different strains have different effects; examples include L. reuteri DSM 17938, studied for infant colic and gut health, and ATCC PTA 6475. Typical dosages for adults range from 200 million to 50 billion colony-forming units (CFUs) daily for up to six months, while children’s doses often range from 100 million to 20 billion CFUs daily.
Safety Profile and Important Considerations
L. reuteri is generally recognized as safe (GRAS) for most healthy individuals. However, like many probiotics, it can cause mild, temporary gastrointestinal side effects such as gas, bloating, stomach discomfort, or diarrhea, especially when first introduced. These symptoms usually subside as the body adjusts.
Certain individuals should exercise caution or consult a healthcare professional before using L. reuteri. This includes those with compromised immune systems, such as individuals undergoing chemotherapy, HIV infection, or severe underlying health conditions. There is a very low risk of probiotic-induced infections in immunocompromised individuals. Pregnant and breastfeeding women are generally advised that L. reuteri is possibly safe, but medical advice is recommended. Those with severe acute pancreatitis or a history of allergies to probiotics should also avoid its use.