According to a new study, antioxidant sulforaphane found in broccoli buds at high concentrations can improve blood sugar levels in some people with prediabetics. The findings suggest the need to personalize treatment for conditions that are precursors of type 2 diabetes.
Broccoli is a nutritious food with proven health benefits. Previous studies have found that it helps prevent cancer in type 2 diabetes, maintain heart and digestive health, and improve blood sugar levels.
A new study led by researchers at the University of Gothenburg, Sweden, found that one of the outstanding compounds in vegetables, the antioxidant sulforaphane, also improved blood sugar levels with a precursor to prediabetic people, type 2 diabetes (T2D).
“While pre-diabetic treatment is currently lacking in many respects, these new findings could be precise treatment using sulforaphane extracted from broccoli as a functional food,” Rosengren was the corresponding author in a previous study on the effects of sulforaphane on blood glucose control in patients with type 2 diabetes. “However, lifestyle factors are the basis for prediabetic treatments, such as exercise, healthy diet and weight loss.”
Prediabetes is characterized by higher than normal blood glucose levels, but not high enough to guarantee a diagnosis of T2D. It usually occurs in people with some degree of insulin resistance, or in people who do not produce enough insulin to maintain blood glucose in their normal range. Current treatment for prediabetes is directed towards correcting lifestyle factors such as improved diet and increased physical activity. In some cases, it is used to lower blood sugar levels using medication.
A common method of screening for prediabetes is to measure blood glucose levels that fast without the effects of food or drink. Normal fasting glucose is usually below 5.6 mmol/L (100 mg/dL), and levels above 7.0 mmol/L (126 mg/dL) usually indicate diabetes. In prediabetic patients, fasting glucose levels are usually between these two values. In this study, 89 people with impaired fasting glucose between 6.1 and 6.9 mmol/L were recruited. Participants were overweight or obese, with a mean age of 63 years, with a mean fasting glucose of 6.4 mmol/L. Sixty-four percent of participants were male.
Participants were randomized and administered broccoli sprout extract (BSE), a concentrated form of bioactive compounds found in broccoli, particularly sulforaphane. Neither the participants nor the researchers knew who was in which group. Broccoli buds can contain up to 100 times more sulforaphane than mature broccoli. Only 74 participants completed all stages of the study. 15 (9 in the BSE group and 6 in the placebo group) were dropped due to gastrointestinal side effects, including nausea, vomiting, reflux and diarrhea.
At the end of the 12-week period, the BSE group had a significantly lower mean fasting glucose than the placebo-administered, with a mean difference of 0.2 mmol/L between groups. A specific clinical subgroup of 13 participants had a “salient response” to BSE. It is mild obesity, low insulin resistance, and lower fasting blood glucose levels. The average reduction in fasting blood glucose was 0.4 mmol/L. The researchers called in responders for these participants.
The researchers used stool samples collected from participants before or after treatment with BSE or placebo to analyze the gut microbiota. The 13 “responders” found significantly different gut microbiota composition at baseline. Eleven of them belonged to the clinical subgroups described in the previous paragraph. Belonging to this subgroup, combined with intestinal bacterial differences, it led to the greatest reduction in fasting blood glucose in response to BSE treatment: 0.7 mmol/L.
The complete cohort of this study did not reach the main results the researchers wanted, but a reduction in fasting blood glucose by 0.3 mmol/L – said their findings were important nonetheless.
“This study shows that responses to sulforaphane-containing BSE in individuals with fasting glucose disorders differ based on host pathophysiology and gut microbiota,” the researchers said. “Together, this demonstrates the need to personalize prediabetic interventions, taking into account that many compounds have overall overall effectiveness, but have a significant impact on specific subgroups, and these findings represent steps towards precision treatment of patients based on individual pathology and gut microbiota.”
One limitation of this study is that the 12-week treatment time did not allow analysis of the long-term effects of BSE on glycemic control, which should be addressed in future studies. Same as the small sample size.
For pre-therapy that don't like the taste of broccoli, but still want to take advantage of the potential blood-lowering effects of sulforaphane, a quick internet search for “sulforaphane supplements” leads to retailers selling capsule antioxidants. However, please do not go overboard. Keep in mind the reasons why people dropped out of this study early.
This study was published in the journal Nature Microbiology.
Source: University of Gothenburg
