June 22, 2017
3 min read

Concentrated broccoli sprout extract may reduce fasting blood glucose in type 2 diabetes, obesity

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A small group of Scandinavian adults with poorly controlled type 2 diabetes and obesity saw a reduction in both HbA1c and fasting plasma glucose with a daily supplement of broccoli sprout extract over 12 weeks when compared with similar adults assigned to placebo, according to findings published in Science Translational Medicine.

“Increased glucose production is a central disease mechanism in type 2 diabetes,” Anders Rosengren, MD, PhD, associate professor at the University of Gothenburg, told Endocrine Today. “Metformin is currently affecting that mechanism, but it cannot be taken by patients with poor kidney function (approximately 15% of patients) or because of stomach problems (5 to 10% of patients). New options are therefore needed. Sulforaphane [in concentrated broccoli sprout extract] also reduces glucose production, but via a different mechanism to that of metformin, by reduced basal gluconeogenesis. Moreover, it has only very mild side effects.”

Anders Rosengren
Anders Rosengren

Rosengren, Annika S. Axelsson, a PhD student in the department of clinical sciences at Lund University Diabetes Center in Malmö, Sweden, and colleagues, analyzed co-expression networks and genetic data to identify a disease signature for type 2 diabetes in liver tissue. The researchers identified sulforaphane via a library of 3,852 drug signatures from publicly available data at the Gene Expression Omnibus, based on experiments with compound treatments of cell lines or primary tissues, as a compound that may reverse the disease signature, according to study background. Sulforaphane is a naturally occurring isothiocyanate found in cruciferous vegetables, such a broccoli and cabbage, and has been studied for its protective effects in models associated with oxidative stress and chemoprotection, the researchers noted.

The researchers then analyzed data from 97 Scandinavian adults diagnosed with type 2 diabetes within the past 10 years; 60 (31 with obesity) had diabetes that was considered well controlled (HbA1c 8%); 37 (17 with obesity) had poorly controlled type 2 diabetes (HbA1c 8.1%). Researchers randomly assigned participants to broccoli sprout extract (containing 150 µmol sulforaphane per dose) or placebo once daily for 12 weeks. All participants provided blood samples and underwent an oral glucose tolerance test at baseline and 12 weeks. Primary outcome was the difference in fasting blood glucose and HbA1c before and after treatment for each participant.

Researchers observed an association between baseline HbA1c levels and change in HbA1c in response to treatment with broccoli sprout extract, with a mean reduction of 0.2 mmol/mol per 1 mmol/mol higher HbA1c at baseline (P = .004); there was no association observed in the placebo group.

At 12 weeks, researchers did not observe a between-group difference in HbA1c for the entire group of participants with poorly controlled diabetes, but within that group, those with BMI at least 30 kg/m² assigned broccoli sprout extract showed a treatment benefit. At 12 weeks, those with type 2 diabetes and obesity assigned broccoli sprout extract had a 1.4% decrease in HbA1c compared with those assigned placebo (P = .034). Researchers also observed a concomitant decrease in fasting blood glucose for those assigned broccoli sprout extract vs. those assigned placebo (8.2 mM vs. 8.9 mM; P = .036). After adjusting for body weight, researchers observed an association between serum sulforaphane concentration and change in fasting blood glucose in those assigned broccoli sprout extract (P = .002).

The extract was well tolerated by most participants; eight participants receiving the extract and seven receiving placebo reported gastrointestinal side effects, typically during the first few days of treatment, according to the researchers.

“High doses of [broccoli sprout extract] cannot yet be recommended to patients as a drug treatment, but would require further studies, including data on which groups of patients would potentially benefit most from it,” the researchers wrote. “Finally, the findings provide support for using disease signatures based on co-expression networks to interrogate drug signatures, thereby using the large, public repositories of gene expression data as one of many strategies for repurposing compounds of immediate clinical relevance.” – by Regina Schaffer

Disclosures: The Novo Nordisk Foundation provided support for this study. Two of the study authors are inventors on patent applications submitted by Lund University that cover the use of sulforaphane to treat exaggerated hepatic glucose production.