Broccoli compound could offer obese diabetics a drug-free way to slash blood sugar levels
Love it or hate it, Swedish scientists have found another reason for you to load up on broccoli, or at least finish what's on your plate. As it turns out, sulforaphane, a powerhouse antioxidant found in the vegetable, could be Nature's secret weapon against type 2 diabetes, offering obese patients a way to slash their blood glucose levels and fight the disease.
This is not the first time sulforaphane has been in the health spotlight. Found in cruciferous greens such as broccoli and cabbage (though if you want to get the most bang for your bite, broccoli sprouts are the way to go), the compound is known for its cancer-fighting and anti-inflammation properties. However hardly anything was known about its effect on type 2 diabetes until now.
Type 2 diabetes occurs when the body isn't able to make enough insulin or to use the hormone to regulate blood glucose levels. This causes a build-up of sugar in the blood and for obese patients, their excess body fat makes it harder for the liver and muscle tissue to absorb this excess blood glucose. At present, type 2 diabetes affects more than 300 million people worldwide and makes up 90 percent of all diabetes cases.
While metformin is the industry standard for controlling blood glucose, the drug is not suitable for everyone, in particular those with reduced kidney function, which affects 15 percent of those with the disease. In addition, it has been reported to cause side-effects such as nausea, bloating, abdominal pain, or diarrhea in some 30 percent of patients who take it.
In their search for an alternative therapy, researcher Annika Axelson of the University of Gothenburg and her colleagues decided to use a different tactic. Instead of targeting an individual gene or protein, they focused on identifying the genes responsible for the liver's elevated glucose production, a key disease mechanism. By analyzing the liver tissue of diabetic mice that had been fed a high-fat diet, they eventually identified a network of 50 genes responsible for causing increased blood glucose levels. This was then matched against different compounds for drugs that could potentially reverse the disease.
Of the 2,800 substances that they investigated, one stood out: sulforaphane. Researchers were alerted to its potential impact on diabetes when they found it tamping down glucose production in cultured liver cells.
When tested in rodents with dietary-induced diabetes, the researchers found that their blood sugar dropped by 23 percent in four weeks when they were given the compound, which was comparable to the 24 percent drop in those that were given metformin. To ensure sulforaphane was directly responsible for this change, they removed it from the extract to see what would happen, and as co-author Anders Rosengren notes, the effect disappeared.
"We also looked at the genes from the liver of the animals and saw that the 50 key genes had been changed in the right direction," he adds.
Encouraged by the results, they tested it on people next. The 12-week randomized placebo-controlled study involved 97 type 2 diabetes patients who were given a powdered broccoli sprout extract containing 100 times the amount of sulforaphane found naturally in broccoli. All, with the exception of three, were also on metformin. Given what they had seen in the animal experiments, the researchers report that it was "not surprising" that sulforaphane had the greatest impact on obese participants with dysregulated diabetes, whose glucose levels decreased significantly while fasting – enough to meet the 7 percent goal recommended by the American Diabetes Association.
Not a silver bullet
That said, while sulforaphane might seem like a miracle worker, there is a limit to what it can do on its own. When rats were fed a high-fructose diet with a 60 percent fat content, the researchers found that even though it had positive side effects, the diet was "too severe a stressor to fully prevent glucose intolerance." In addition, as the researchers note in the study, the extract "did not change body weight, BMI, liver parameters, cholesterol concentration, plasma triglycerides, or blood hemoglobin concentration [in obese human patients.]" In other words, patients will also need to adopt appropriate lifestyle habits to get the most out of the therapy. As numerous studies have shown, diet and an active lifestyle are key to preventing and reversing the disease.
Moving forward, the researchers will continue to study the potential of broccoli sprouts extract as an alternative drug treatment. In addition, since all the participants involved in the study were Scandinavian, more data is also needed to document its impact on other groups of patients, such as those with pre-diabetes.
"High doses of BSE 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," note the authors.
If all goes well, the researchers say the plan is to bring the broccoli sprout extract to market within two years – and there's a good reason it would be better as a pill. To experience the benefits reported in the study, a person with diabetes would need to eat four to five kilograms (8.8 to 11 pounds) of broccoli a day.
That said, manufacturers of metformin need not worry. Rather than see it as a competitor, the researchers regard sulforaphane as a "supplement to existing medication." Metformin works by decreasing the amount of glucose that the liver releases into the blood stream and also makes cells more receptive to insulin. Sulforaphane, on the other hand, stops the liver enzymes from over-producing glucose and also has the advantage of having mild side-effects, thus offering those who can't take metformin a viable alternative. As a naturally occurring compound, it could also have other benefits.
"As functional food, it can reach the patients faster than a medication, and it is also an interesting concept from a diabetes perspective where diet is central," says Rosengren.
The study was published in Science Translational Medicine.
Source: Lund University