Many people with prediabetes never receive structured treatment, even though early intervention offers the best chance of reversing high blood sugar. While lifestyle changes are the primary recommendation, they are challenging to implement and often ineffective. A recent study found that a broccoli sprout extract rich in sulforaphane modestly lowered fasting blood sugar in some people with prediabetes.

Researchers conducted a 12-week, randomized, double-blind, placebo-controlled trial involving 74 participants with prediabetes who had not previously taken medication for the condition. Participants took a daily dose of broccoli sprout extract or a placebo, and researchers measured changes in their fasting blood sugar. They also analyzed gut microbial composition and genetic markers to explore potential differences in response.

Overall, the extract slightly reduced fasting blood sugar levels (3.6 milligrams per deciliter, mg/dL) compared to the placebo but did not meet the predefined target for effectiveness. However, a subgroup of participants with mild obesity, lower insulin resistance, and reduced insulin secretion saw a greater reduction in blood sugar—about 7.2 mg/dL. These participants also had a distinct gut microbiota composition, including a higher abundance of bacterial genes linked to sulforaphane activation.

Sulforaphane forms when glucoraphanin, found in broccoli sprouts, interacts with the enzyme myrosinase. Myrosinase activates when the plant cells are damaged, such as during chewing or processing. In the absence of myrosinase, some people’s gut microbes produce similar enzymes, helping convert more glucoraphanin into sulforaphane. This variation in gut bacteria may explain why some people respond more strongly to sulforaphane-rich foods or supplements.

These findings suggest that gut microbes and individual metabolic traits may influence the effectiveness of nutritional interventions for prediabetes. One in three people in the U.S. has prediabetes. Learn more in this clip featuring Dr. Michael Snyder.