Key Points:
- A new study from the University of Gothenburg suggests that a compound in broccoli sprouts, sulforaphane, may help lower fasting blood glucose (sugar) levels in people with prediabetes.
- Participants who took a sulforaphane supplement for 12 weeks saw greater reductions in blood sugar than those who took a placebo.
- The most significant improvements were seen in people with mild age-related diabetes, low insulin resistance, and certain gut bacteria linked to better sulforaphane absorption.
How broccoli may help blood sugar
We all know that eating vegetables is good for our health, but new research suggests that broccoli might have a particularly powerful effect on blood sugar levels. A study from the University of Gothenburg found that sulforaphane — a natural compound found in broccoli sprouts — may help reduce blood sugar levels in people with prediabetes.
The study, published in the journal Nature Microbiology, builds on previous research showing that sulforaphane can improve blood sugar management in people with type 2 diabetes.
This time, researchers focused on prediabetes — a condition in which blood glucose levels are high but not high enough to be considered diabetes. With an estimated 10% of Swedes affected by prediabetes and no clear treatment guidelines in place, researchers hope these findings could lead to more targeted prevention strategies.
What the study evaluated
The study involved 89 adults between the ages of 35 and 75 who had elevated fasting blood sugar, were overweight or obese, and had no prior diabetes diagnosis. Participants were randomly assigned to take either a sulforaphane supplement or a placebo (inactive treatment) once daily for 12 weeks, without knowing which one they were receiving. A total of 74 participants completed the full study.
What the study found
The results showed that participants taking the sulforaphane supplement had a greater reduction in fasting blood sugar levels compared to those taking the placebo. On average, the sulforaphane group saw a 0.2 mmol/l (3.6 mg/dl) drop in blood sugar, with some subgroups experiencing even more significant benefits:
- People with early signs of mild age-related diabetes had an average reduction of 0.4 mmol/l (7.2 mg/dl).
- Those with specific gut bacteria linked to sulforaphane absorption saw up to a 0.7 mmol/l (12.6 mg/dl) decrease.
The group with the greatest improvement tended to have lower insulin resistance, lower body-mass index (BMI, a measure of weight relative to height), a lower incidence of fatty liver disease, and reduced insulin secretion. This suggests that sulforaphane may be most effective in people with a milder metabolic profile.
“These new findings open the way for possible precision treatment using sulforaphane extracted from broccoli as a functional food,”
said lead researcher Professor Anders Rosengren, MD, PhD, of the University of Gothenburg. “However, lifestyle factors such as exercise, diet, and weight management remain the foundation of any prediabetes treatment.”
Why this matters
Prediabetes often goes undetected, but early intervention can significantly reduce the risk of developing type 2 diabetes. While lifestyle changes like healthy eating and regular exercise are the first line of defense, not everyone responds to them in the same way. This study suggests that sulforaphane supplements could be particularly helpful for people with specific metabolic profiles and gut bacteria.
“The results of this study not only point to the potential of sulforaphane as a functional food but also highlight the role of gut bacteria in determining how well certain treatments work,” Rosengren added.
Limitations and next steps
While the findings are promising, researchers emphasize that this was a relatively small study. More extensive trials are needed to confirm the long-term benefits and safety of sulforaphane supplements.
Future research will also explore whether a single dose of sulforaphane can immediately improve blood sugar management and whether the compound has additional benefits for people with obesity.
The bottom line
This study adds to a growing body of evidence that what we eat can directly impact our blood sugar levels and overall health. While broccoli isn’t a magic cure, its active compound, sulforaphane, may offer another tool for managing prediabetes — especially for people with specific metabolic traits.
For more details, check out the press release from the University of Gothenburg and the full study in Nature Microbiology.
Want to learn more about managing prediabetes? Read What Is Prediabetes? Symptoms, Treatments, and More and Prediabetes: What to Know.
