Mulberry May Reshape Gut Bacteria, but How It Is Processed Could Matter Most

Mulberry may influence the bacteria living in the gut and affect processes linked to metabolism, according to a review published June 30, 2026, in Biomolecules and highlighted by Wroclaw Medical University on Sept. 30.

The researchers found promising effects from mulberry leaves, fruits, and their extracts in laboratory and animal studies, but they have not yet been confirmed in human clinical trials.

The research points to an important detail that could be easy to miss: not all mulberry products are likely to work in the same way. The species of mulberry, the part of the plant used, and even how it is dried, fermented, or extracted can change its chemical makeup and, in turn, its interaction with gut bacteria.

Why mulberry is attracting attention

Mulberry contains several natural compounds that can interact with the digestive system. Its leaves are particularly rich in 1-deoxynojirimycin, or DNJ, along with polyphenols and polysaccharides. Fruits, especially black mulberry, contain anthocyanins and other phenolic compounds.

Some of these substances can reach the colon, where gut bacteria can break them down and produce compounds called short-chain fatty acids, including acetate, propionate and butyrate. These substances are involved in normal intestinal function and can interact with metabolic processes.

Professor Anna Prescha of Wroclaw Medical University, one of the researchers, explained the connection simply: “The gut microbiota not only contributes to the functioning of the gastrointestinal tract but may also influence metabolism throughout the body.”

The review found that experimental mulberry preparations were sometimes associated with changes in bacteria such as Bifidobacterium, Lactobacillus, and Akkermansia, along with changes in short-chain fatty acid production. Some studies also reported changes in glucose regulation, lipid metabolism and inflammation.

The surprising role of processing

One of the more interesting findings is that the way mulberry is prepared can change its effects.

Drying, fermentation and extraction can alter the amount and type of compounds left in a final product. Even two extracts made from the same plant material can therefore have different chemical profiles.

The review found that processing methods can also affect how mulberry polysaccharides are used by gut bacteria. In laboratory experiments using human fecal material, different extraction methods produced polysaccharide preparations with different fermentation behavior and short-chain fatty acid production.

That means a finding involving a concentrated laboratory extract should not automatically be applied to fresh mulberries, tea, or a commercially available supplement.

What happened in mouse studies?

Some of the strongest results came from experiments involving mice fed high-fat diets.

Researchers studied a preparation containing both polyphenols and polysaccharides from white mulberry fruit. The combination was associated with changes in gut bacteria and improvements in some measures linked to metabolic syndrome and intestinal health.

In another experiment, researchers transferred gut bacteria from treated mice into other mice. The recipient animals also showed improvements in some metabolic disturbances. The review said this provided evidence that gut bacteria may have contributed to at least part of the observed effects.

This does not mean eating mulberries will produce the same results in people. The experiments involved specific preparations, doses, and animal models.

Why the findings are not yet a health recommendation

The biggest gap is the lack of well-controlled human trials specifically examining whether mulberry preparations can change the human gut microbiome and produce measurable metabolic benefits.

The researchers said most of the current evidence comes from animal experiments and laboratory fermentation studies. They also noted that many studies use different mulberry species, extracts, and processing methods, making the results difficult to compare directly.

Prescha emphasized that the evidence remains preliminary: “The available findings are promising, but at this stage they do not allow us to determine whether the relationships observed in experimental models between mulberry preparations, the microbiota, and metabolism also occur in humans.”

The researchers say future human studies should use clearly defined and standardized mulberry preparations so scientists can determine which products, doses, and processing methods actually affect the gut microbiome.

For now, the research suggests that the interesting part of mulberry may not simply be the fruit or leaf itself. What is inside the plant, how it is processed, and how gut bacteria respond to those compounds may all determine what happens next.