“Eating broccoli could reverse the damage caused by diabetes to heart blood vessels”, BBC News reported. It said that researchers have found that the compound sulforaphane, found in the vegetable, encourages the production of enzymes which protect blood vessels and cause a reduction in the number of molecules that can damage cells.
This story is based on a complex laboratory study in which sulforaphane was directly applied to blood vessels that had been damaged by high blood sugar levels. It found that the compound reduced the production of potentially damaging molecules called reactive oxygen species. However, the results have been overinterpreted by the news; applying the compound in broccoli to cells in the laboratory is not comparable to eating broccoli. The blood vessel cells were not taken from a person with diabetes but had been incubated with sugar. It is unclear what effects sulforaphane would have on the blood vessels of a person with diabetes, and whether it would protect them from damage or have any effect upon the disease process. Optimal blood sugar control through diet and medication remains the best option for people with diabetes.
Dr Mingzhan Xue and colleagues from the University of Warwick and University of Essex carried out the research. It was supported by Juvenile Diabetes Research Foundation International, the Wellcome Trust, and the Biotechnology and Biosciences Research Council. The study was published in the peer-reviewed medical journal: Diabetes.
The aim of this laboratory study was to look at whether sulforaphane, a compound found in broccoli, could prevent metabolic damage to small blood vessels caused by high blood sugar. Sulforaphane activates a protein called nrf2, which initiates the production of a number of enzymes that protect cells from potentially damaging chemicals, including a type of free radical called reactive oxygen species (ROS).
The researchers incubated cells taken from the lining of human small blood vessels with two different concentrations of sugar – low and high. They then used laboratory methods to see what effects incubation with sulforaphane had on a range of complex metabolic and biochemical pathways. The researchers used concentrations of sulforaphane that they said were representative of the levels that have been reported to be found in the blood stream after eating broccoli.
The researchers found that activation of the protein nrf2 by sulforaphane, caused increased expression of various protective and metabolic enzymes, including three to five fold increases in the enzymes transketolase and glutathione reductase.
Incubating blood vessel cells in high sugar concentrations resulted in a three-fold increase of the potentially harmful free radical ROS, but adding sulforaphane reduced ROS levels by 73%. The enzyme transketolase played a role in this reduction. Sulforaphane also prevented the production of other chemicals that may potentially cause blood cell dysfunction in high blood sugar conditions.
The researchers concluded that activation of nrf2 may prevent the biochemical dysfunction of cells that line the inside of blood vessels caused by high levels of blood sugar.
The news report overinterpreted the results of this complex laboratory study.
Optimal blood sugar control through diet and medication remains the best option for people with diabetes, and broccoli should be considered only as part of a healthy diet.