Bifidobacterium adolescentis: Benefits of the Gut Bacterium That Feeds Other Gut Bacteria

Bifidobacterium adolescentis benefits your gut mostly by feeding other gut bacteria, and it is one of the main bifidobacteria that stay in the gut into adulthood. It breaks down fibre and starch from plant foods and releases acetate, which other gut bacteria use to make butyrate, the main fuel for the cells lining your colon. If you have seen B. adolescentis on a probiotic label, it helps to know what it does and how to feed it.

In short:

• B. adolescentis is one of the main bifidobacteria in adult guts, adapted to plant fibre and starch.
• Its main benefit is indirect: it turns fibre into acetate, which other bacteria use to make butyrate, a type of short-chain fatty acid that serves as the main fuel for the cells lining your colon.
• Onions, garlic, leeks, oats, and rice or potatoes that have been cooked and cooled supply the fibres and starches it uses.
• Human trials of specific strains are few and small, so most of what it does is known from laboratory studies.

What is Bifidobacterium adolescentis?

Bifidobacterium adolescentis is a bacterium that lives in the large intestine of adults and feeds on plant fibres and starches your own body cannot digest. In a Japanese study of 441 people aged 0 to 104, the guts of adults were dominated by B. adolescentis and its close relative B. catenulatum, while babies' guts were dominated by B. breve and B. longum.

That shift follows the diet. The bifidobacteria that dominate in babies are suited to the sugars in breast milk. B. adolescentis is suited to the solid, plant-based food that replaces it, which is why it stays with you into adulthood.

What does B. adolescentis do in your gut?

B. adolescentis breaks down fibres and starches into acetate and lactate, and other gut bacteria use those products to make butyrate. This handover between species is called cross-feeding, and it works like a relay. B. adolescentis runs the first leg, and butyrate producers such as Faecalibacterium prausnitzii finish the race.

F. prausnitzii is one of the most abundant bacteria in a healthy colon, and butyrate is the main fuel for the cells lining it. In a laboratory study, F. prausnitzii grown together with B. adolescentis on fibre made more butyrate than F. prausnitzii grown alone, and the acetate levels fell over the same period as F. prausnitzii used it up.

The benefits of B. adolescentis depend on the community around it. This is because your gut microbiome is an ecosystem, where what one species does depends on and impacts the others it lives with. At the moment, most research still tests one strain or species at a time, because single strains are easier to isolate, dose and measure. So the evidence on what B. adolescentis can do alone is still thin, and it may not capture everything it does in your gut, where its effects depend on which other bacteria are there.

What are the benefits of Bifidobacterium adolescentis?

The best-supported benefit of B. adolescentis is helping other bacteria make butyrate, shown in laboratory studies. Human evidence is limited to a few small studies of specific strains.

• More butyrate from fibre. In laboratory co-cultures, B. adolescentis raised the butyrate that F. prausnitzii made from fibre and starch.
• A response to resistant starch. In a study of 10 adults who ate crackers made with different types of resistant starch for three weeks each, one type (chemically modified wheat starch) raised B. adolescentis, and bifidobacteria rose about tenfold in three of the participants.
• Fewer symptoms of lactose intolerance. In a two-week pilot trial of 21 people with lactose intolerance, the strain iVS-1 at 1 billion CFU a day reduced symptoms such as bloating, abdominal pain and diarrhoea compared with placebo. Researchers linked to the company that sells the strain were among its authors.
• GABA production. Some B. adolescentis strains produce GABA, a compound that carries signals in the nervous system, and two strains raised GABA levels in rats. This has not been tested in people.

Each of these findings belongs to a specific strain or setting, so they describe what the species can do, and a product's strain needs its own evidence. If you are choosing a probiotic, look for the strain code on the label and check what that strain has been tested for.

How do you increase Bifidobacterium adolescentis naturally?

You can feed the B. adolescentis you already have with inulin-type fibres and resistant starch, the two kinds of carbohydrate it is equipped to break down. Foods that supply them include:

• Inulin-type fibres: onions, garlic, leeks, chicory and slightly green bananas.
• Resistant starch: oats, barley, legumes, and rice or potatoes that have been cooked and then cooled, since cooling turns some of the starch into a resistant form.

Responses vary between people, because a fibre can only feed the bacteria that are already there. If you do not eat much fibre now, adding a lot at once can cause gas and bloating for a week or two, so increase it gradually. Begin with one small step: swap one serving of freshly cooked rice this week for rice that was cooked and cooled in the fridge.

Is Bifidobacterium adolescentis safe?

For most healthy adults, yes. B. adolescentis is a normal resident of the adult gut, and bifidobacteria have a long history of use in food and supplements. Side effects reported in trials of bifidobacteria are usually mild and digestive, such as gas or bloating in the first days.

Speak to a doctor before starting any supplement if you are immunocompromised, pregnant or breastfeeding, taking prescribed medication, or managing a diagnosed condition.

Does taking Bifidobacterium adolescentis as a supplement work?

A B. adolescentis supplement can only help if a live strain survives the capsule and your stomach and then becomes active in your colon, and the research on each of those steps is still early. Having it in your gut and getting it there from a capsule are separate questions.

Survival is the first hurdle. Bifidobacteria differ in how well they survive oxygen and stomach acid, so how a product is made, packed and delivered matters.

Once it arrives, its advantage is that it is adapted to the adult gut. In a three-week trial in adults with obesity, the strain IVS-1 reached higher numbers in stool than BB-12, a common commercial strain that is not native to the human gut, and raised total bifidobacteria about as much as the prebiotic GOS did. Taking IVS-1 was also linked to better results on one test of gut barrier function.

In most probiotic trials, supplemented strains are found mainly while people are taking them, which is why probiotics are usually taken every day. A strain does not need to settle permanently to be active. While it passes through your colon, it can break down fibre and pass acetate to the butyrate producers already living there, the cross-feeding described above. Regular doses keep it present for that, although this handover has so far been shown mainly in laboratory studies.

AMILI's Metabolic Health formulation delivers a B. adolescentis strain with inulin, a fibre it can use, in a targeted-release capsule designed to protect it from oxygen and stomach acid, though neither the strain on its own nor the finished formulation has been tested in a human trial yet. Here is how Metabolic Health works.

This article is for general information and isn't a substitute for personalised medical advice. If you have ongoing gut symptoms, speak with a doctor.

Frequently Asked Questions

1. Does Bifidobacterium adolescentis produce butyrate?
   No. It produces acetate and lactate. Butyrate producers such as Faecalibacterium prausnitzii take up that acetate and turn it into butyrate, which is why B. adolescentis is described as a cross-feeder.
2. What is the difference between Bifidobacterium adolescentis and Bifidobacterium infantis?
   Their food. B. infantis is suited to the sugars in breast milk and is common in babies. B. adolescentis is suited to plant fibres and starches and is common in adults.
3. What foods increase Bifidobacterium adolescentis?
   Foods rich in inulin-type fibres and resistant starch, such as onions, garlic, leeks, slightly green bananas, oats, barley, legumes, and rice or potatoes that have been cooked and cooled.
4. Is Bifidobacterium adolescentis in most probiotics?
   No. Most bifidobacteria probiotics use B. animalis subsp. lactis or B. longum. B. adolescentis appears in fewer products, so look for it by name on the label.
5. What is resistant starch?
   Starch that passes through the small intestine undigested and reaches the colon, where bacteria such as B. adolescentis break it down. Cooking and then cooling starchy foods like rice and potatoes increases the amount.
6. Can I take Bifidobacterium adolescentis with other probiotics?
   It is often combined with other strains in multi-strain products. Trials have not consistently shown that combinations work better than single strains, so judge each product by the evidence for its specific strains.

Glossary

• Acetate: A short-chain fatty acid that bifidobacteria make from fibre. Other gut bacteria use it to make butyrate.
• Butyrate: A short-chain fatty acid made by certain colon bacteria. It is the main fuel for the cells lining the colon.
• CFU (colony-forming units): A measure of how many live microbes a product contains.
• Cross-feeding: When one gut bacterium's products become another bacterium's food, as when B. adolescentis produces acetate that butyrate producers use.
• GABA (gamma-aminobutyric acid): A compound that carries signals in the nervous system. Some gut bacteria can produce it.
• Inulin: A type of fibre found in onions, garlic, leeks and chicory, which bifidobacteria can break down.
• Lactose intolerance: Difficulty digesting lactose, the sugar in milk, which can cause bloating, pain and diarrhoea.
• Resistant starch: Starch that escapes digestion in the small intestine and is broken down by bacteria in the colon.
• Strain: A genetically distinct type within a species, usually shown as a code after the species name. Findings for one strain do not automatically apply to another.

About the Author

Yuzu Tay is a science communicator trained in biomedical engineering and leads marketing and communications at AMILI. Her focus is on translating and sharing real science to help people make better decisions about their health, staying close to what the evidence does and does not show. Her work spans cancer companion diagnostics, liver fibrosis and gut health.

References

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