Scientists discovered that a popular probiotic bacteria called Bifidobacterium breve comes in different versions, and these versions behave very differently in babies’ guts. Some versions might actually make eczema worse, while others help prevent it. Researchers compared the genetic makeup of bacteria from babies with and without eczema and found that even though the bacteria look similar overall, they have important differences in genes that control immune responses. This discovery suggests that not all probiotics work the same way for every baby, and doctors may need to be more careful about which specific strains they recommend.

The Quick Take

  • What they studied: Whether different versions of the same probiotic bacteria affect babies’ skin health differently, and what genetic differences might explain why
  • Who participated: Three groups of infants: those with eczema (atopic dermatitis), those recovering from eczema, and those without eczema. Bacteria samples came from their stool samples.
  • Key finding: The bacteria version found in babies with eczema had different immune-related genes compared to the version in healthy babies, and these differences affected how well the bacteria could reduce inflammation
  • What it means for you: If you’re considering probiotics for your baby’s eczema, know that the specific strain matters just as much as the species. Not all versions of the same bacteria will help equally, so talk to your pediatrician about which specific strains have evidence behind them.

The Research Details

Researchers collected stool samples from three groups of infants and isolated the Bifidobacterium breve bacteria from each group. They then used advanced genetic sequencing technology to read the complete DNA code of three different bacterial strains—one from a baby with eczema, one from a baby recovering from eczema, and one from a healthy baby without eczema.

After mapping out the genetic differences, the scientists performed laboratory tests to see how each bacterial strain affected immune cells. They measured whether each strain could reduce inflammation, which is the body’s overactive response that causes eczema symptoms.

This approach allowed researchers to connect genetic differences directly to how the bacteria actually behaved in immune responses, rather than just assuming all versions of the same bacteria work the same way.

Most probiotic research treats all versions of a bacteria species as identical, but this study shows that’s not accurate. Different strains can have completely different effects on health. This is important because it explains why some babies might get worse when given certain probiotics—they might be getting a strain that doesn’t help their particular immune situation.

This is a preliminary study with a very small sample size (only three bacterial strains tested), so the findings need to be confirmed with larger studies. The genetic analysis is solid and the immune testing was done in controlled laboratory conditions. However, laboratory results don’t always match what happens in a real baby’s gut, so more research is needed before changing medical recommendations.

What the Results Show

The three bacterial strains looked very similar when scientists compared their overall genetic makeup—they shared about 95% of their DNA. However, when researchers focused specifically on genes related to immune function, they found meaningful differences between the strain from babies with eczema and the strain from healthy babies.

The most important finding came from the immune tests: the bacteria from healthy babies (strain MHL_0062) was much better at reducing inflammation compared to the bacteria from babies with eczema (strain MHL_0001). This suggests that the genetic differences in immune-related genes actually translate into real differences in how the bacteria affects the body’s inflammatory response.

The bacteria from the baby recovering from eczema (strain MHL_0043) showed intermediate results, suggesting it might be transitioning between the two states.

The research suggests that Bifidobacterium breve bacteria may actually change or adapt based on the baby’s immune system and health status. Rather than the bacteria causing eczema, it appears the bacteria might be responding to the baby’s existing immune imbalance. This is an important distinction because it means the presence of this bacteria alone doesn’t determine whether a baby will have eczema.

Earlier studies had noted that babies with eczema often had higher amounts of Bifidobacterium breve in their guts, which seemed confusing since this bacteria is marketed as beneficial. This new research explains that puzzle: the bacteria itself isn’t necessarily bad, but certain strains of it may not provide the same protective benefits as other strains. This aligns with growing evidence that probiotic effects are strain-specific, not species-specific.

The study examined only three bacterial strains from a very small number of infants, so the findings may not apply to all babies or all versions of this bacteria. The immune testing was done in laboratory dishes, not in actual human bodies, so results might differ in real-world conditions. The study also didn’t track what happened to these babies over time, so we don’t know if these bacterial differences predict future eczema development. More research with larger groups of babies and longer follow-up periods is needed.

The Bottom Line

Based on this research, parents should be cautious about giving probiotics to babies with eczema without consulting their pediatrician. If a doctor recommends a probiotic, ask specifically which strain is in the product, not just which species. Look for products that specify the exact strain (like ‘Bifidobacterium breve MHL_0062’ rather than just ‘Bifidobacterium breve’). This is preliminary research, so it should inform conversations with doctors but not replace their medical judgment. Confidence level: Low to Moderate—this is early-stage research that needs confirmation.

Parents of babies with eczema or a family history of eczema should pay attention to this research. Pediatricians and dermatologists treating infant eczema should consider strain-specific effects when recommending probiotics. Healthy babies without eczema don’t need to change anything based on this study. People with adult eczema should note this is specific to infants and may not apply to them.

If a probiotic is started, it typically takes 2-4 weeks to see any effects on eczema symptoms. However, this research suggests that some strains might not help at all, so if there’s no improvement after a month, switching to a different strain or stopping might be worth discussing with your doctor.

Want to Apply This Research?

  • If using a probiotic for infant eczema, track the specific strain name and daily eczema severity (redness, itching, skin barrier damage) on a 1-10 scale. Record this weekly to see if there’s a pattern of improvement or worsening over 4-6 weeks.
  • When selecting a probiotic product, users should photograph the label and save the specific strain information in the app. Create a reminder to check the product’s strain name before purchasing refills, ensuring consistency in the strain being used.
  • Set up a monthly review where you compare eczema photos and severity scores to identify whether the current probiotic strain is helping. If no improvement appears after 4-6 weeks, note this in the app and discuss switching strains with your pediatrician rather than continuing an ineffective product.

This research is preliminary and based on a very small sample size. It should not be used to make decisions about your baby’s medical care without consulting your pediatrician or dermatologist. Probiotics are not regulated the same way as medications, and their safety and effectiveness vary. Never start, stop, or change your baby’s probiotic without medical guidance. If your baby has eczema, work with a healthcare provider to develop a comprehensive treatment plan. This article is for educational purposes only and does not constitute medical advice.