Netherlands Study: Breast Milk Sugar May Help Gut Recover After Antibiotics

A study from the Netherlands has uncovered a promising — though still early-stage — strategy for protecting gut health after antibiotic treatment, with potential implications for people living with obesity and diabetes.

What Researchers Did

Scientists at Maastricht University Medical Center gave participants a powerful antibiotic called vancomycin for seven days — long enough to significantly disrupt the gut microbiome. Afterward, half the participants took a supplement called 2'-fucosyllactose (2'-FL) for eight weeks, while the other half received a placebo. 2'-FL is a type of prebiotic sugar naturally found in human breast milk and is already used in some infant formulas.

The study was randomized and double-blind, meaning neither the patients nor the researchers knew who received the real supplement — the gold standard of clinical research.

What They Found

Vancomycin caused significant damage to the gut microbiome, reducing the richness and diversity of beneficial bacteria and lowering levels of short-chain fatty acids (SCFAs) — compounds your gut bacteria produce that help regulate blood sugar and inflammation.

Participants who took 2'-FL showed measurably better gut microbiome recovery after just two weeks compared to those on placebo. However, this advantage disappeared by the end of the eight-week period, suggesting the benefit was temporary.

On a more encouraging note, eight weeks of 2'-FL supplementation did reduce fasting levels of interleukin-6 (IL-6), an inflammatory marker closely linked to insulin resistance and type 2 diabetes risk. Unfortunately, no significant improvements were seen in glucose tolerance or insulin sensitivity during the study period.

Understanding the Numbers

While this study did not report specific blood glucose targets in mmol/L, it's worth noting that US guidelines define normal fasting glucose as under 100 mg/dL, prediabetes as 100–125 mg/dL, and diabetes as 126 mg/dL or higher. The participants in this Dutch study were adults with overweight or obesity — a population that mirrors a large share of Americans at risk for or managing type 2 diabetes.

Why This Matters for US Patients

Americans with diabetes or prediabetes are frequently prescribed antibiotics for common infections. What many patients — and even some providers — don't fully appreciate is that antibiotics like vancomycin can cause lasting disruption to the gut microbiome, which plays a critical role in blood sugar regulation, inflammation control, and metabolic health.

This Dutch research matters for US patients because:

• Obesity is a shared challenge. With over 42% of American adults classified as obese, findings from this overweight/obese population are directly relevant.
• Gut health is metabolic health. SCFAs produced by gut bacteria help improve insulin sensitivity — a key concern for the 38 million Americans living with diabetes.
• A simple supplement may help. 2'-FL is already available in some prebiotic supplements in the US, though it is not yet FDA-approved as a therapeutic intervention for this purpose.
• Inflammation reduction matters. Lower IL-6 levels could translate to reduced insulin resistance over time, though more research is needed.

The Bottom Line

This research is promising but preliminary. The gut microbiome benefits were short-lived, and metabolic improvements were limited. US patients should not start taking 2'-FL supplements without consulting their healthcare provider — but this study adds to a growing body of evidence that protecting your gut microbiome during and after antibiotic use may be an important part of diabetes management.

Original Study: Vliex, Barnett, Monzel. Gut Microbes, 2025. PMID: 41243448. DOI: 10.1080/19490976.2025.2580693