Allulose Modulates Oral Microbiota and Biofilm Formation by Lowering Cariogenic Potential

Why this matters for formulators

If you replace sucrose with allulose, the sweetness stays close. But the oral microbiome sees something entirely different. A 2025 study in Frontiers in Cellular and Infection Microbiology (DOI: 10.3389/fcimb.2025.1670139) tested allulose against sucrose, glucose, fructose, xylitol, and erythritol. The results put allulose on the low-cariogenic side of the sweetener spectrum.

This matters because dental caries is not just about sugar intake. It is a microbial disease. Streptococcus mutans feeds on fermentable sugars, makes acid, and builds a sticky biofilm. If an alternative sweetener does not drive those steps, formulators gain a real functional edge—not just a calorie reduction.

Background: Caries is a biofilm problem

Caries develops when oral bacteria convert carbohydrates into organic acids. Those acids demineralize enamel. S. mutans also produces extracellular polymeric substances, or EPS. The EPS forms a scaffold around microcolonies. That scaffold gives plaque its structure and protects bacteria from saliva and antimicrobials.

Sucrose is uniquely cariogenic because it fuels both acid production and EPS synthesis. Many bulk sweeteners fail on that second point. Some support acid, some disrupt the matrix, some do both. The question for allulose was simple: does it act like a fermentable sugar or a non-fermentable polyol?

What the study did

The researchers evaluated allulose head-to-head with the five other sweeteners. They measured bacterial growth, acid production, biofilm architecture, and expression of key virulence genes in S. mutans. They also looked at microbial diversity in biofilms formed under each sugar condition. This is not a short-term pH spot-check. It is a full view of the ecological outcome.

Key findings

Allulose supported lower bacterial growth and lower acid production than sucrose, glucose, and fructose. That pattern matched xylitol and erythritol. Acid production under allulose was 99% lower than under sucrose. Let that number sink in.

Biofilms formed in the presence of allulose lacked the dense EPS-wrapped microcolonies and dome-shaped structures seen with sucrose. They also maintained higher microbial diversity. A sucrose biofilm becomes a dense, acid-tolerant monopoly. The allulose biofilm stays more balanced.

The gene expression data reinforce the phenotype. S. mutans virulence genes gtfD, ldh, and atpD were significantly downregulated under allulose. gtfD is involved in EPS production. ldh drives lactate production. atpD supports acid tolerance. All three dropped. The organism was not just producing less acid; it was turning down the entire caries toolbox.

Substrate	Bacterial growth / acid output	Biofilm structure	Virulence gene expression
Allulose	Low growth, low acid (99% less acid than sucrose)	No dense EPS-wrapped microcolonies; no dome structures; higher microbial diversity	gtfD, ldh, atpD significantly downregulated
Sucrose	Higher growth and acid than allulose	Dense EPS scaffold, microcolonies, dome architecture	High cariogenic expression
Glucose/fructose	Higher growth and acid than allulose	Not detailed in this abstract	Not detailed in this abstract
Xylitol/erythritol	Low growth, low acid	Non-fermentable pattern	Low cariogenic expression

The takeaway is not that allulose is identical to erythritol or xylitol. It is that allulose behaves like them in the traits that matter for caries formation.

What it means for manufacturers

You can formulate with allulose and pursue oral-health positioning if you have the regulatory support to back it. This study gives you mechanistic evidence. It does not give you a clinical caries claim. Use it as a stepping stone.

For products like chewing gum, lozenges, ready-to-drink beverages, and bakery items, allulose now has a stronger rationale beyond sugar reduction. It can be positioned as a sweetener that does not feed the caries process the way sucrose does. That is valuable in children's products, medical nutrition, and any brand with dental health in its messaging.

But final product matrices matter. pH, calcium, and other carbohydrates can shift oral biofilm responses. Do not assume a single sweetener behaves identically in every formula. Run your own assays or partner with a contract research lab before you go to market with a tooth-friendly label.

FAQ

Is allulose cariogenic like sucrose? No. In this study, allulose produced 99% less acid than sucrose and downregulated key caries virulence genes in S. mutans.

Does allulose act like xylitol and erythritol? It shares their key traits: low fermentation, low acid, no dense EPS biofilm. The study described allulose's performance as similar to non-fermentable sugar alcohols, though the exact metabolic pathways may differ.

Can I use this study to market allulose products as tooth-friendly? Not alone. This is a mechanistic in vitro study, not a clinical caries trial. You still need claim substantiation that meets your target market's regulations. Use this data as part of your evidence package.

The formulation lens

Allulose is often compared to sugar for taste and bulk. This study shifts the comparison to oral ecology. Sucrose feeds the bacteria, fuels the acid, and builds the fortress. Allulose does none of that in this model. It leaves the biofilm weaker, less acidic, and more diverse. For a food scientist, that is a meaningful difference. For a consumer with caries concerns, it might be the difference that sells the product.