Can Probiotics Help Prevent Colds in Children?

If you have kids, you know how frustrating cold and flu season can be.

One child gets sick, another catches it a few days later, and before you know it, someone in the house has been coughing or dealing with a runny nose for the better part of a month.

It's also one of the reasons parents are increasingly interested in supplements that might help support their children's immune systems.

Probiotics are particularly interesting because their potential benefits extend beyond digestion. Certain bacterial strains can influence immune signaling, and researchers have been investigating whether those effects might translate into fewer respiratory infections.

A new 2026 study published in Patient Preference and Adherence examined what happened when children with a history of respiratory infections took a combination of two probiotic strains for four weeks.

The results were impressive at first glance.

More than 95% of caregivers reported that their children experienced fewer colds.

But there's a major limitation in the study design that changes how we should interpret that number.

And I think that limitation is just as important as the results themselves.

TLDR

A new 2026 study followed 236 children who took a two-strain probiotic supplement for four weeks.

• 95% of caregivers reported fewer colds. This was a perception reported after supplementation, not a measured 95% reduction in infection risk.
• 94% reported fewer medical visits. Parents also reported improvements in respiratory symptoms, but there was no untreated comparison group.
• Sleep, energy, and digestion appeared to improve. Caregivers reported several quality-of-life benefits beyond respiratory symptoms.
• The study was not placebo-controlled. Every participant received probiotics, making it impossible to determine how much of the improvement was actually caused by supplementation.
• The specific strains matter. Researchers used Lacticaseibacillus rhamnosus CRL1505 and Bifidobacterium breve M-16V. The results cannot automatically be applied to every probiotic supplement.

My takeaway: Probiotics are worth investigating for respiratory health, but this study provides observational evidence of perceived improvements rather than proof that probiotics prevent colds in children.

Why Would Gut Bacteria Affect Respiratory Health?

At first, the idea that bacteria living in your intestines could influence infections in your nose, throat, or lungs might seem a little strange.

But the gastrointestinal tract and respiratory system are connected through several immune and metabolic pathways.

Researchers often refer to this relationship as the gut-lung axis.

Your intestinal microbiome interacts with immune cells, influences the production of certain metabolites, and helps regulate the intestinal barrier.

Some of those immune signals can have effects beyond the digestive tract.

For example, microbial activity in the gut may influence how the immune system responds to respiratory pathogens and regulates inflammation.

This doesn't mean that taking probiotics creates some kind of protective barrier against every virus you're exposed to.

The immune system is considerably more complicated than that.

It does, however, provide a plausible reason why certain probiotic strains might influence respiratory infection risk or symptom severity.

And that distinction between certain strains and probiotics in general is important.

The Two Probiotic Strains Used in This Study

The researchers used a combination of two specific bacterial strains.

Lacticaseibacillus rhamnosus CRL1505

This strain has been investigated for its potential effects on immune responses, particularly those involved in respiratory infections.

Previous experimental research has examined how CRL1505 influences antiviral signaling, including interferon-related pathways and mucosal immune activity.

Those mechanisms are interesting because interferons help coordinate the body's response to viral infections.

However, observing immune effects in experimental research doesn't automatically establish that supplementation will prevent respiratory infections in children.

Bifidobacterium breve M-16V

This strain has been studied primarily in relation to early-life gut microbiota development, intestinal barrier function, and immune regulation.

It's particularly interesting in infants and young children because their intestinal microbiomes and immune systems are still developing.

The researchers proposed that combining these two strains might provide complementary benefits.

CRL1505 could potentially influence respiratory immune defenses, while M-16V could help support intestinal microbial balance and immune regulation.

That's a reasonable biological hypothesis, but this particular study didn't directly measure the immune mechanisms involved.

The researchers didn't assess interferon concentrations, immune-cell activity, or changes in the intestinal microbiome.

They primarily relied on caregiver-reported symptoms and quality-of-life assessments.

How the Researchers Conducted the Study

The study was conducted across 35 participating sites in 15 provinces throughout China between January and December 2025.

Researchers recruited children between birth and 14 years of age who had experienced at least one respiratory tract infection during the previous three months.

A total of 254 children completed the initial questionnaire, and 236 completed the four-week intervention.

The participants were divided into three age categories.

Each child received a daily six-drop dose of an oil-based probiotic product containing approximately 2 billion colony-forming units (CFU) of the two bacterial strains combined.

Supplementation continued for four weeks.

Caregivers completed questionnaires about respiratory symptoms, illness frequency, healthcare visits, digestion, sleep, energy, and overall well-being.

The researchers also collected information about product acceptability and reported adverse events.

There was one major difference between this study and the randomized controlled trials I usually prefer to examine.

There was no placebo group.

Every child received the probiotic supplement.

That means the researchers could document what caregivers reported during and after supplementation, but they couldn't determine what would have happened without the supplement.

Keep that in mind as we look at the results.

The Results: 95% of Caregivers Reported Fewer Colds

This was easily the most attention-grabbing finding.

After four weeks of supplementation, 225 of the 236 caregivers, or 95.34%, reported that their children were experiencing fewer colds.

That's an unusually high percentage for any intervention intended to reduce respiratory infections.

But there's something important about how the researchers collected this information.

The percentage represents the proportion of caregivers who perceived a reduction in cold frequency compared with their child's usual illness pattern.

It does not mean the supplement reduced the number of colds by 95%.

And because there was no placebo group, we don't know how many parents would have reported similar improvements without supplementation.

Children naturally experience fluctuations in respiratory symptoms. A child who has been sick repeatedly over several months may simply experience fewer illnesses during the next four weeks.

That's especially relevant when the study recruits children based on a recent history of respiratory infections.

Still, the researchers reported several other interesting outcomes.

The consistency of these reports is interesting, but I wouldn't consider them convincing evidence of efficacy on their own.

Without a control group, we cannot separate the effects of probiotics from natural recovery, changes in exposure to respiratory viruses, or parental expectations.

What About Symptom Severity and Recovery Time?

The researchers also asked caregivers about changes in respiratory symptoms.

Approximately 22.9% reported complete symptom disappearance, while another 57.6% reported marked improvement.

Combined, that means roughly 80% of caregivers reported substantial improvement in their children's respiratory symptoms.

Another 16.9% reported moderate improvement.

The study also found that 58.5% of caregivers reported symptom relief within one to three days.

That sounds encouraging, but I think we need to be especially careful with this result.

Many uncomplicated respiratory infections naturally begin improving within several days.

Without knowing when each infection began, what pathogen caused it, and how symptoms progressed in an untreated group, it's impossible to attribute rapid symptom relief to probiotics.

The researchers suggested that early improvements might reflect changes in innate immune signaling.

That's biologically plausible, but the study didn't measure immune responses or establish that probiotics were responsible for the timing of symptom improvement.

I wouldn't use these findings to claim that taking probiotics will help a child recover from a cold in three days.

Did Probiotics Reduce Doctor Visits?

Another interesting finding involved healthcare utilization.

The researchers reported that 94.49% of caregivers perceived a reduction in medical visits associated with respiratory infections.

Of those participants, 64.41% reported a marked decrease and 30.08% reported a slight decrease.

The largest proportion reporting marked reductions was among school-aged children.

If probiotic supplementation could reliably reduce respiratory infections severe enough to require medical attention, that would be a meaningful benefit.

Fewer illnesses could mean fewer missed school days, less time away from work for parents, and potentially less unnecessary antibiotic use.

But this study didn't demonstrate those outcomes causally.

The medical-visit results were based on caregiver reports of changes relative to their children's previous illness patterns, rather than a controlled comparison of prospectively verified medical visits.

I think reducing healthcare visits is an important outcome to study, but these results are preliminary.

A stronger trial would compare documented respiratory infections and medical visits between children randomly assigned to probiotics and those receiving a placebo.

Probiotics May Have Benefits Beyond Respiratory Health

One aspect of the study I found interesting was the reported improvement in general well-being.

Caregivers weren't only asked about coughs, runny noses, and respiratory symptoms.

They also evaluated changes in appetite, digestion, energy, sleep, and gastrointestinal comfort.

Approximately one-third of caregivers reported improvements in appetite and digestion, energy levels, or sleep quality.

Children younger than three were also more likely to experience reported improvements in constipation or diarrhea compared with older children.

That age-related difference reached statistical significance.

These findings make some biological sense.

The intestinal microbiome plays an important role in gastrointestinal function, and certain probiotic strains have been studied for their potential effects on digestion and intestinal barrier integrity.

But once again, the study didn't include a placebo group.

And there's another possibility worth considering.

If a child experiences fewer respiratory symptoms for any reason, their appetite, sleep, and energy may naturally improve as well.

So these quality-of-life findings don't necessarily represent independent effects of probiotics.

They may simply reflect the same perceived improvement in overall health.

Why the Specific Probiotic Strains Matter

One mistake I see frequently in supplement marketing is treating all probiotics as though they're interchangeable.

They're not.

Even two bacterial strains belonging to the same species can have different characteristics and produce different physiological effects.

That's why probiotic research needs to be interpreted at the strain level whenever possible.

In this study, the researchers used:

• Lacticaseibacillus rhamnosus CRL1505

• Bifidobacterium breve M-16V

The total daily dose was approximately 2 billion CFU.

That doesn't mean every probiotic containing Lactobacillus or Bifidobacterium will produce similar results.

It also doesn't mean taking a higher CFU dose will necessarily produce greater benefits.

More bacteria isn't automatically better.

The strain, dose, formulation, viability, and outcome being studied all matter.

If you're considering probiotics for a particular health goal, I'd pay much more attention to the specific strains and the research supporting them than to the total CFU count printed on the front of the bottle.

The Biggest Problem With This Study

I think this is the most important section of the entire article.

The researchers described the study as a large, prospective, community-based investigation.

And in fairness, it did include 236 children across numerous participating sites.

That's useful for understanding how a supplement is used and perceived in everyday settings.

But a large study isn't necessarily a strong study.

The quality of the evidence depends heavily on how the study is designed.

In this case, every child received the probiotic supplement.

There was no random assignment to a placebo group, no blinding, and no concurrent untreated comparison group.

That creates several problems.

1. Children often recover naturally

Respiratory infections are usually self-limiting.

If you recruit children who have recently experienced repeated infections, some will naturally have fewer symptoms during the following month.

This is sometimes referred to as regression toward the mean.

It's particularly relevant when participants are selected because they've recently experienced an unusually high number of illnesses.

2. Parents knew their children were receiving probiotics

Caregiver expectations can influence subjective reporting.

If a parent believes probiotics support immune health, they may be more likely to notice improvements or interpret normal fluctuations in symptoms as a supplement benefit.

That doesn't mean caregivers were being dishonest.

It means human perception is influenced by expectations, which is one of the reasons placebo-controlled studies are so important.

3. Respiratory infections vary seasonally

The study took place across 2025, but each child was followed for only four weeks.

Respiratory infection exposure can vary considerably depending on the season, school attendance, household exposures, and circulating viruses.

Without a comparison group followed during the same period, those influences are difficult to separate from supplementation.

4. Most outcomes weren't objectively verified

The researchers used structured questionnaires and performed some checks against clinic records.

That's better than relying entirely on informal recollection.

However, they didn't use laboratory-confirmed infection diagnoses, viral testing, or objective immune measurements to establish that the probiotic reduced respiratory infections.

5. The statistical significance can be misleading

The study reported highly significant p-values for several outcomes.

But some of those tests evaluated whether the proportion of caregivers reporting improvement exceeded an assumed 50% threshold.

That is not the same as demonstrating that probiotics work better than placebo.

You can have an extremely small p-value and still lack the study design needed to establish causation.

This is one of those situations where I think the study's methodology matters much more than the headline percentages.

What About the Safety Findings?

The researchers reported no adverse or serious adverse events during the four-week intervention, and no participants discontinued because of adverse events.

The product was also generally well accepted.

Approximately 83% of caregivers rated its palatability as good or excellent, and more than 99% said they would probably or definitely recommend it.

Those are encouraging findings for short-term tolerability.

However, I wouldn't interpret them as proof that probiotic supplementation is safe for every child.

The study excluded children with immune deficiencies, certain congenital conditions, hereditary metabolic disorders, and known allergies to the product's components.

It also lasted only four weeks.

Children with significant medical conditions, especially those who are immunocompromised, may require additional precautions with live microbial supplements.

And because this study included infants and very young children, I think it's especially important for parents to discuss probiotic supplementation with their pediatrician rather than assuming that a supplement marketed for immune health is automatically appropriate.

Should Parents Give Their Kids Probiotics to Prevent Colds?

Based on this study alone, I wouldn't make that recommendation.

The results are interesting, but they don't demonstrate that probiotics prevent respiratory infections.

That said, this isn't the only research examining probiotics and respiratory health.

Previous randomized trials and systematic reviews have found that certain probiotic strains may modestly reduce the incidence or duration of upper respiratory tract infections.

The overall evidence is more encouraging than what we can conclude from this single observational study.

But results vary depending on the bacterial strains, participant populations, and outcomes measured.

So I wouldn't assume that purchasing any probiotic supplement will meaningfully reduce the number of colds your child experiences.

If your child has frequent respiratory infections, I'd start by discussing the pattern with their pediatrician, particularly if infections are unusually severe, prolonged, or accompanied by poor growth or other concerning symptoms.

Vaccinations, appropriate sleep, nutrition, hand hygiene, and avoiding exposure to tobacco smoke remain important foundations of respiratory health.

Probiotics may eventually become a useful additional strategy for certain children, but they shouldn't replace established preventive care.

What I Think This Study Actually Tells Us

I think there's a tendency to get excited whenever a supplement study reports that 90% or more of participants experienced a benefit.

And I understand why.

Those numbers look impressive.

But when I see a study reporting that 95% of parents noticed fewer colds and 98% noticed better quality of life, my first question isn't how effective the supplement must be.

It's how those outcomes were measured.

In this case, the researchers relied on caregiver perceptions without a placebo-controlled comparison.

That makes it impossible to know how much improvement was caused by the probiotic.

I don't think that makes the study worthless.

It provides useful information about product acceptability, short-term tolerability, and what caregivers reported during supplementation.

It also gives researchers a reason to investigate this particular combination of strains more carefully.

But I wouldn't use these results as evidence that the supplement prevents 95% of colds, dramatically strengthens immunity, or produces rapid improvements in respiratory health.

The study simply wasn't designed to establish those conclusions.

I also think it's worth noting that several researchers were employees of the company that supplied the probiotic product.

The authors disclosed this relationship and stated that the company employees did not control the study's design or analysis. The study also reported public project funding.

Industry involvement doesn't automatically invalidate research, but it's another reason to examine the methodology rather than relying on the authors' conclusions alone.

The Bottom Line

A new 2026 study involving 236 children found that four weeks of supplementation with Lacticaseibacillus rhamnosus CRL1505 and Bifidobacterium breve M-16V was associated with caregiver-reported improvements in respiratory symptoms, medical visits, and overall quality of life.

More than 95% of caregivers reported fewer colds, and nearly 98% reported improvements in general well-being.

Those numbers are interesting, but they need to be interpreted in the context of the study design.

There was no placebo group, and the primary outcomes were based on caregiver perceptions rather than objectively confirmed changes in infection rates.

My takeaway is that probiotics remain a promising area of research for respiratory health, but this study doesn't prove they prevent colds in children.

I'd like to see a properly randomized, double-blind trial using these exact strains, with documented respiratory infections and medical visits measured over an entire cold and flu season.

That would tell us considerably more about whether the reported benefits translate into meaningful protection.

Until then, I'd view probiotics as a potentially useful, strain-specific intervention that still needs stronger evidence for this particular application.

About the Author

Matt Mosman, MS, CISSN, CSCS, is the founder and Chief Science Officer of Simply Good Supplements. With a background in exercise science, sports nutrition, and strength and conditioning, Matt focuses on turning research into practical advice that athletes, parents, and everyday active people can actually use.

References

Zhang Y, Li X, Yuan J, Liong M-T, Chen D, Cai M. Effects of Probiotics on Respiratory Tract Infections and Quality of Life in Children: A Large, Prospective, Community-Based Study. Patient Preference and Adherence. 2026;20. https://doi.org/10.2147/PPA.S598488