Lactobacillus reuteri is a beneficial bacterium found in the human digestive system. This probiotic strain has gained attention for its health benefits, particularly its potential connection to weight management, which is an area of ongoing scientific exploration.
How L. reuteri May Influence Weight
L. reuteri may influence body weight through several biological mechanisms that affect gut health and metabolism. One key pathway involves its ability to modulate the gut microbiota composition. Some research suggests that specific strains of L. reuteri can alter the balance of gut bacteria, potentially increasing beneficial microbes like Akkermansia and Clostridium, which have been linked to improved metabolic health.
The bacterium also appears to regulate bile acid metabolism. For instance, L. reuteri J1 has been shown to increase levels of ursodeoxycholic acid (UDCA) and lithocholic acid (LCA) in mice. These bile acids may lead to reduced triglyceride accumulation in the liver.
L. reuteri may additionally promote adipose browning, a process where white fat cells (which store energy) transform into brown-like fat cells (which burn energy to produce heat). This effect has been observed in mice, where L. reuteri J1 upregulated uncoupling protein 1 (UCP1) expression. Furthermore, L. reuteri may influence hormones that regulate appetite and satiety, such as leptin and ghrelin, potentially helping to control food cravings and promote a balanced caloric intake.
Scientific Evidence and Research
Current scientific research on L. reuteri and weight loss has largely been conducted in animal models, showing promising results. Studies in mice have demonstrated that supplementation with certain L. reuteri strains can prevent weight gain, reduce fat mass, and improve glucose homeostasis and insulin sensitivity. For example, L. reuteri ATCC PTA 4659 prevented diet-induced obesity in mice, with reduced adipose and liver weights. Another mouse study with L. reuteri ATCC 6475 noted a 50% reduction in visceral fat pads and inhibited fat gain from high-fat diets.
Human studies, while fewer and more preliminary, have also explored the potential effects. One study involving overweight human subjects reported that daily supplementation with L. reuteri for 12 weeks led to reductions in body weight, waist circumference, and body fat percentage compared to a placebo group. In another human trial, L. reuteri SD5865 showed some metabolic effects, but did not directly alter insulin sensitivity or body fat distribution.
The effects of L. reuteri can be highly strain-dependent. While some strains, like ATCC PTA 4659, have shown anti-obesity effects, others, such as L. reuteri L6798, have been associated with increased weight gain in mice. Moreover, some research in humans has linked the presence of L. reuteri to obesity, indicating that the relationship is complex and requires further investigation.
Sources and Considerations
L. reuteri can be obtained through dietary sources, though it is not commonly found in many fermented foods. Some yogurts, sourdough breads, miso, kimchi, and sauerkraut may contain certain L. reuteri strains. However, the concentration and specific strains in these foods can vary widely.
Probiotic supplements are a more reliable way to obtain specific strains of L. reuteri. Strains like L. reuteri ATCC PTA 6475 and L. reuteri DSM 17938 are well-researched and known to survive oral supplementation. Research doses typically range from 1 billion to 100 billion colony-forming units (CFUs) daily.
While L. reuteri is generally considered safe for most healthy individuals, some people may experience mild digestive upset, such as gas, bloating, or mild abdominal pain, especially when first starting supplementation. Diarrhea can also occur, though it is often temporary. Individuals with compromised immune systems, severe gastrointestinal conditions, or those who have recently undergone surgery should consult a healthcare professional before taking L. reuteri or any new probiotic supplement.