20 June 2017

Broccoli extract shows promise for type 2 diabetes

A substance in this crunchy vegetable may help diabetics gain better control of their blood sugar.


There are few children – or adults – who are naturally fond of broccoli, and moms have a notoriously difficult time to get their kids to eat this green vegetable.

It now turns out that your mom may have been right about broccoli's goodness all along. A small study suggests that a substance in this vegetable may help diabetics gain better control of their blood sugar.

Researchers found that a concentrated extract of the substance, called sulforaphane, helped obese type 2 diabetes patients rein in their stubbornly high blood sugar levels.

The findings were published in Science Translational Medicine.

Small, short-term study

Previous research has found that the sulforaphane in broccoli also blocks the enzymes that cause joint destruction in osteoarthritis – the most common form of arthritis.

In addition, broccoli has been discovered to be an extremely potent cancer-fighting agent, and that three to five servings a week are enough to have a noticeable effect.

In the current study, the caveat, however, is that the study was short-term and small – involving 97 people with diabetes followed for 12 weeks. And the extract was taken in addition to the diabetes drug metformin, not instead of it.

Plus, the extract the researchers used was not like the sulforaphane supplements available at your local health food store.

"The way that you produce and process the extract is important to keep the sulforaphane intact," said senior researcher Dr Anders Rosengren, of the University of Gothenburg, in Sweden.

He said his team used a highly concentrated supplement that was tested for purity and side effects.

Reducing inflammation

"At this point," Rosengren said, "we cannot recommend that anyone take the currently available extracts on the market to treat type 2 diabetes."

Sulforaphane is a chemical found in cruciferous vegetables such as cauliflower, Brussels sprouts and broccoli. Broccoli sprouts are a particularly rich source.

So Rosengren's team recruited 97 people with type 2 diabetes. All were of Scandinavian ethnicity. Almost all of them were on metformin, a first-line treatment for type 2 diabetes. The majority of them were doing well; however, 37 patients still had poorly controlled blood sugar, the study authors noted.

Half of the group was randomly assigned to take sulforaphane powder once a day for 12 weeks, in addition to their usual medication. The other half received a placebo (inactive) powder.

The sulforaphane powder was hardly a panacea. In the end, the supplement appeared to be effective only for specific patients – namely, those who were obese and had poorly controlled blood sugar to start.

Patent applications

For this group, average haemoglobin A1C level went from almost 7.4% to just over 7%. An A1C test gives a snapshot of a person's blood sugar levels over the past two to three months.

Rosengren said his team is planning further trials. They aim to test sulforaphane in people with pre-diabetes to see if it can lower the odds of progression to full-blown type 2 diabetes.

Rosengren and a colleague are named as inventors on patent applications covering the use of sulforaphane for lowering the liver's production of glucose.

But if broccoli and other veggies naturally provide the chemical, is a supplement even necessary?

According to Rosengren, a person would have to eat more than a plateful of broccoli each day to get the amount of sulforaphane used in this study.

However, he added, "increasing your daily intake of broccoli could certainly be good from many viewpoints."

Read more:

Broccoli brilliance

Broccoli may prevent arthritis

Broccoli may ease allergies


Ask the Expert

Diabetes expert

Dr. May currently works as a fulltime endocrinologist and has been in private practice since 2004. He has a variety of interests, predominantly obesity and diabetes, but also sees patients with osteoporosis, thyroid disorders, men's health disorders, pituitary and adrenal disorders, polycystic ovaries, and disorders of growth. He is a leading member of several obesity and diabetes societies and runs a trial centre for new drugs.

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