Published on June 4, 2025
Is it enough to take L. reuteri in capsule form for just a few days – or is yogurt more useful in the long term?
The question of whether taking Limosilactobacillus reuteri in capsule form for a few days can permanently change something in the gut is a frequently asked question. Here are the most important scientifically proven facts:
1. Temporary settlement, not permanent colonization
Contrary to popular belief, L. reuteri does not permanently colonize the intestine when ingested orally. Several studies show that even probiotic strains with high tolerability and efficacy usually only pass through the intestine temporarily as long as they are administered regularly. If intake is discontinued, the detectable amount of these bacteria disappears within a few days to weeks (Walter et al., 2018; Derrien & van Hylckama Vlieg, 2015).
This is due, among other things, to the fact that the original ecological niches for these bacteria have been lost in Western societies due to modern diets, medications (especially antibiotics), and hygiene standards (Blaser, 2014). Permanent establishment is rarely successful under these conditions.
Taking capsules for just a few days is usually not enough. It's all about continuous intake , similar to a plant that needs regular watering to thrive.
2. Capsule vs. yogurt – differences in effectiveness and costs
While L. reuteri capsules are a convenient option, homemade yogurt offers several advantages:
- Cost : A single capsule can produce up to 20 servings of yogurt through fermentation. This makes the yogurt significantly more affordable —especially when used daily.
- Dosage : The yogurt contains many times more bacteria than a single capsule. Studies show that probiotic effects are often dose-dependent (Ouwehand et al., 2002).
- Additional metabolites : Fermentation produces postbiotic substances such as short-chain fatty acids, B vitamins or bioactive peptides, which can also have health-promoting effects (Wegh et al., 2019).
Survival rate of probiotics in the stomach: capsules vs. yogurt
Challenges for probiotics in the stomach
The human stomach, with its acidic pH (approximately 1.5 to 3.5), presents a significant barrier to orally administered probiotics. Many probiotic strains are sensitive to this acid and can be inactivated during gastric passage.
Survival rate in probiotic capsules
A study investigated the resistance of various commercial probiotics to simulated gastric conditions. The results showed that many of these products, particularly those without an enteric coating, had a low survival rate. Some products showed a reduction in viable bacteria of up to 3 logs, equivalent to a 1,000-fold reduction, after 90 minutes in an acidic environment (pH 2).
A further study confirmed that many probiotic capsules without special protective mechanisms are not sufficiently resistant to stomach and bile acids, which calls into question their effectiveness.
Survival rate in fermented dairy products such as yogurt
In contrast, fermented dairy products like yogurt provide a protective matrix for probiotic bacteria. One study showed that probiotic strains in yogurt exhibited a higher survival rate during gastric transit. This is attributed to the buffering capacity of milk proteins and other components of yogurt, which increase the pH in the stomach and thus mitigate the acid effect.
Additionally, combining probiotics with dairy products has been found to significantly improve bacterial survival compared to water. In one study, certain Lactobacillus strains survived up to 197% better in milk than in water.
The survival rate of probiotic bacteria during gastric transit is crucial for their effectiveness in the gut. Studies show that fermented dairy products such as yogurt provide a protective environment that mitigates the acidic effects of the stomach, thus increasing the survival rate of the probiotics. In contrast, many probiotic capsules, especially those without an enteric coating, can have a lower survival rate.
Therefore, regular consumption of probiotic yogurt may be a more effective way to reap the benefits of probiotic bacteria.
3. Long-term effect requires long-term application
Many of the documented positive effects of L. reuteri, such as on oxytocin production, muscle mass, sleep, or mood, only occurred after several weeks of daily intake . The effect is not based solely on short-term colonization, but rather on the bacteria's ongoing interaction with the immune system, the enteric nervous system, and hormonal axes (Varian et al., 2016; Poutahidis et al., 2013).
Summary:
- Taking L. reuteri capsules for several days is not sufficient, as the strain does not usually settle permanently in the intestine .
- Regular intake is necessary for a lasting effect.
- Homemade yogurt is more effective, cheaper and contains additional health-promoting substances.
- The positive effects usually only occur after continuous use over several weeks .
Sources:
- Blaser MJ (2014). Missing Microbes . Henry Holt.
- Derrien M & van Hylckama Vlieg JET (2015). Fate, activity, and impact of ingested bacteria within the human gut microbiota. Trends in Microbiology , 23(6), 354–366.
- Ouwehand AC et al. (2002). Probiotic and other functional microbes: from markets to mechanisms. Current Opinion in Biotechnology , 13(5), 483–487.
- Poutahidis T et al. (2013). Microbial symbionts accelerate wound healing via the neuropeptide hormone oxytocin. PLoS One , 8(10):e78898.
- Varian BJ et al. (2016). Beneficial bacteria inhibit cachexia. Oncotarget , 7(9), 11803–11816.
- Walter J et al. (2018). Establishing or Exaggerating Causality for the Gut Microbiome: Lessons from Human Microbiota-Associated Rodents. Cell , 174(4), 800–804.e6.
- Wegh CA et al. (2019). Postbiotics and Their Potential Applications in Early Life Nutrition and Beyond. International Journal of Molecular Sciences , 20(19), 4673.
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