Scientists studied different types of a common gut bacteria called Bifidobacterium adolescentis to understand which ones might be healthier for us. They looked at the genes and tested 15 different strains in the lab. They found that while all strains could break down lactose and make helpful vitamins, there were big differences in how much they produced. Some strains were better at handling resistant starch, and most made a brain-friendly chemical called GABA. The study shows that not all bacteria of the same species work the same way, which matters when choosing probiotics.

The Quick Take

  • What they studied: Whether all strains of a common gut bacteria called Bifidobacterium adolescentis have the same helpful health properties, or if some strains are better than others
  • Who participated: The researchers analyzed genetic information from 148 different isolates of this bacteria and then tested 15 representative strains in laboratory conditions
  • Key finding: All strains could break down lactose and make vitamins, but there were huge differences in how much they produced. For example, GABA production ranged from barely detectable to 14.4 units, and only 66% of strains could use resistant starch effectively
  • What it means for you: If you’re considering a probiotic supplement with this bacteria, the specific strain matters a lot. Two products might look the same but have very different effects on your body. This suggests we need better labeling and testing of probiotic products to know what we’re actually getting

The Research Details

This was a two-part investigation. First, researchers used genetic sequencing to map out the family tree of 148 different samples of Bifidobacterium adolescentis bacteria, looking for how different they were from each other. They identified five major groups based on their genes. Second, they looked at the genes responsible for breaking down different types of carbohydrates (the bacteria’s food sources) and found three distinct patterns. Finally, they selected 15 representative strains and grew them in laboratory dishes to test what they could actually do—could they break down lactose, handle resistant starch, make helpful chemicals, and produce vitamins?

This approach is important because genes don’t always tell the whole story. A bacteria might have the genes to do something but not actually do it very well. By combining genetic analysis with real laboratory testing, the researchers could see both what the bacteria were capable of and how well they actually performed. This gives a much clearer picture than either method alone

The study was published in mSphere, a reputable peer-reviewed journal. The researchers used a large sample size (148 isolates) and tested multiple different properties. However, all testing was done in laboratory dishes, not in human bodies, so results may differ in real-world conditions. The study was descriptive rather than testing whether these bacteria actually improve health in people

What the Results Show

Every single strain tested could break down lactose and produce folate (a B vitamin), but the amounts varied wildly. Lactose-breaking ability ranged from 2 to 232 units, and folate production ranged from 23 to 281 nanograms per milliliter. This means some strains are much better at these jobs than others. About two-thirds of the strains (66%) could use resistant starch, which is a type of carbohydrate that feeds beneficial gut bacteria. The ability to use resistant starch ranged from 26% to 74% efficiency. Most strains (80%) produced GABA, a chemical that may help with mood and anxiety, but again with huge variation from barely detectable to 14.4 units.

The researchers also looked for genes related to making antimicrobial compounds (natural antibiotics) and found them in only 7% of the bacteria. Genes for antibiotic resistance were found in 23% of the strains, which is important for safety considerations. Interestingly, the bacteria that were most closely related genetically didn’t necessarily have the most similar abilities—some cousins were very different from each other in what they could do

This study confirms what smaller previous studies suggested: that Bifidobacterium adolescentis is common in healthy people and centenarians, and it does make helpful compounds. However, this is the first large-scale study showing just how much variation exists between different strains. Previous research often assumed all strains of the same species were basically the same, but this work shows that assumption is wrong

All testing was done in laboratory dishes, not in human bodies, so we don’t know if these differences matter in real life. The study didn’t test whether these bacteria actually improve health outcomes in people. The lab conditions were artificial and may not reflect what happens in your actual gut. Additionally, the study didn’t identify which specific genes cause the differences in abilities, so we can’t yet predict which strains will be best just by looking at their genes

The Bottom Line

If you’re considering a probiotic supplement containing Bifidobacterium adolescentis, look for products that specify the exact strain (not just the species name). Ask manufacturers for evidence that their specific strain has been tested for the properties you want (lactose tolerance, mood support, etc.). This is a moderate-confidence recommendation based on this research—it makes logical sense but hasn’t been proven in human studies yet

This matters most for people with lactose intolerance, those interested in mood support, or anyone considering probiotic supplements. It’s less relevant if you’re just eating fermented foods like yogurt, which contain multiple strains. People with compromised immune systems should be cautious about any probiotics and should consult their doctor. This research is interesting for healthy adults but shouldn’t replace medical advice

If these bacteria do help, you’d likely need to take them regularly for at least 2-4 weeks to notice any effects, though this hasn’t been tested in this study. Benefits would probably be modest and gradual rather than dramatic

Want to Apply This Research?

  • If using a probiotic app, track the specific strain name and manufacturer of any probiotic you take, along with weekly notes on digestive comfort (bloating, gas, regularity) and mood. Rate each on a 1-10 scale to see if there are patterns
  • Instead of just buying any probiotic, use the app to research and record the specific strain information from the label. Set a reminder to take your probiotic consistently at the same time daily, and track which strain you’re using so you can compare effects over time
  • Create a 12-week tracking plan: weeks 1-2 establish baseline, weeks 3-8 track consistency and any changes, weeks 9-12 evaluate overall effects. If switching strains, restart the tracking to compare. Keep notes on brand, strain name, and any changes in digestion or mood

This research describes laboratory findings about bacterial properties and has not been tested in human clinical trials. The study does not prove that these bacteria improve health in people. Before starting any probiotic supplement, especially if you have a medical condition, take medications, or have a compromised immune system, consult with your healthcare provider. This information is for educational purposes and should not replace professional medical advice. Individual results may vary significantly based on your unique gut microbiome and health status.