Lactobacillus reuteri, often shortened to L. reuteri, is a type of beneficial bacteria that naturally resides within the human body. As a probiotic, it contributes to the complex community of microorganisms that support various bodily functions. This bacterium has gained increasing recognition for its potential to promote overall health and well-being.
Understanding Lactobacillus reuteri
Lactobacillus reuteri is a Gram-positive, rod-shaped bacterium that thrives in low-oxygen environments, making it anaerobic. In April 2020, it was reclassified to Limosilactobacillus reuteri, reflecting advancements in scientific understanding of its taxonomy.
This bacterium is commonly found in natural habitats like the gastrointestinal tract of humans and other animals, breast milk, and certain fermented foods. It is a commensal organism, living in harmony with its host without causing harm. Each host tends to harbor its own specific strains of L. reuteri, highlighting the diversity within this species.
The presence and abundance of L. reuteri can vary among individuals, and it is not universally found in all humans. Dietary supplementation can help maintain higher levels of this beneficial bacterium in those who may have deficiencies. Oral intake of L. reuteri has been shown to temporarily colonize the intestines of healthy individuals within days of ingestion, though levels may decrease if supplementation stops.
Mechanisms of Action
Lactobacillus reuteri exerts its beneficial effects through several mechanisms. One way it contributes to health is by producing reuterin, a potent antimicrobial compound. This substance can inhibit the growth of harmful bacteria, fungi, and some viruses.
Beyond producing antimicrobials, L. reuteri competes directly with undesirable bacteria for nutrients and adhesion sites within the gut. This competition helps maintain a balanced gut microbiota, preventing the overgrowth of pathogenic microbes. It also contributes to a healthy gut environment by producing organic acids, such as lactic acid, which can lower the intestinal pH and create an unfavorable environment for harmful bacteria.
L. reuteri also modulates the host’s immune system. It influences the production of cytokines, signaling molecules that regulate immune responses. Some strains reduce pro-inflammatory cytokines while increasing anti-inflammatory mediators, promoting a balanced immune response. This modulation helps maintain immune tolerance and control inflammation.
L. reuteri contributes to the production of short-chain fatty acids (SCFAs) like acetate, beneficial metabolites for gut health. These SCFAs nourish gut cells and can have systemic effects, including influencing immune regulation. Some strains also synthesize certain vitamins, such as folate and vitamin B12.
Key Health Benefits
The health benefits associated with Lactobacillus reuteri are varied and supported by scientific research, particularly for digestive health. This probiotic can reduce excessive crying in infants, known as colic. It also improves gut motility and helps manage various forms of diarrhea, slightly reducing its duration in children.
In terms of broader digestive well-being, L. reuteri promotes a balanced gut microbiome, which is foundational for efficient digestion and nutrient absorption. It may help alleviate symptoms of irritable bowel syndrome (IBS), with individuals often experiencing reduced bloating and abdominal discomfort. The bacterium also aids in combating harmful pathogens that can disrupt digestive health and has been explored as an adjuvant strategy for Helicobacter pylori infections, potentially reducing side effects from standard drug therapies.
Beyond the gut, L. reuteri supports the immune system by fostering a healthy balance of gut bacteria, which in turn strengthens the body’s defenses. A robust gut barrier, enhanced by probiotics like L. reuteri, reduces the risk of infections and inflammation. Research suggests its effectiveness in reducing the frequency and severity of respiratory infections, especially in children.
L. reuteri also benefits oral health, thriving in the mouth. By maintaining a healthy balance of oral bacteria, it contributes to overall oral hygiene and reduces the risk of common dental issues. It also influences the gut-skin axis, suggesting a role in managing conditions like eczema and acne by minimizing inflammation.
Sources and Considerations
Individuals can obtain Lactobacillus reuteri through various avenues, though the most reliable sources are typically supplements. While L. reuteri is naturally present in breast milk and some traditionally fermented foods like certain yogurts or kefirs, the amounts are often unquantified and can vary significantly. The presence of specific beneficial strains in these natural sources is not guaranteed.
Probiotic supplements are considered the primary reliable source for consistent and targeted intake of L. reuteri. These supplements are available in different forms, such as drops, capsules, and powders, offering flexibility in administration. Dosing often ranges from 200 million to 50 billion colony-forming units (CFUs) daily for adults, and 100 million to 20 billion CFUs daily for children, typically for up to six months.
When considering supplementation, L. reuteri is generally recognized as safe for consumption. However, some individuals may experience mild and temporary side effects, such as gastrointestinal discomfort, including gas, bloating, or mild abdominal pain, especially when first starting supplementation. These symptoms usually subside as the digestive system adjusts. While L. reuteri is often used to treat diarrhea, in some instances, particularly at high doses, it might cause loose stools.
It is important to choose reputable brands that specify the strain of L. reuteri, as different strains can have varying effects. Individuals with compromised immune systems, such as those undergoing chemotherapy or with HIV/AIDS, should consult a healthcare professional before starting any probiotic regimen due to a slight, albeit rare, risk of infection. Additionally, those with severe gastrointestinal conditions or very premature infants should seek medical advice to ensure appropriateness.