UK researchers said that eating broccoli could reverse the damage done to heart blood vessels by diabetes because the vegetable contains a compound called sulforaphane that they tested in the lab and found it increased enzymes that protect heart blood vessels and reduced the molecules that damage them.

The study is the work of Professor Paul Thornalley and colleagues at the University of Warwick, and is published in the online 4th August issue of the journal Diabetes.

People with diabetes have a five times greater risk of developing heart disease and stroke, primarily because of damage to heart blood vessels from having about three times the normal level of circulating oxidative molecules called Reactive Oxygen Species (ROS) caused by having high blood glucose (hyperglycaemia).

From previous studies, the researchers already knew that eating lots of vegetables, and brassicas like broccoli in particular, was significantly linked to lower risk of heart disease and stroke, and wondered if this had anything to do with the presence of sulforaphane which is known to activate a protein called nrf2 (short for NF-E2-related factor-2) that switches on genes that increase antioxidants and a number of protective and metabolic enzymes.

For this particular study, Thornalley and colleagues wanted to find out if activating nrf2 using sulforaphane would prevent metabolic dysfunction under conditions of hyperglycemia in the type of cells found in heart blood vessels. So they cultured human microvascular HMEC-1 endothelial cells in low and high glucose concentrations (3 and 30 mMole) and assessed the effect of adding sulforaphane on multiple pathways of biochemical dysfunction, increases in ROS, and other metabolic processes.

The results showed that:

  • There was a significant reduction in ROS molecules.
  • Sulforaphane reversed the increase in ROS caused by hyperglycemia by 73 per cent.
  • Sulforaphane doubled the activation of nrf2, leading to increased production of antioxidant and detoxifying enzymes in human microvascular cells.

The authors concluded that:

“Activation of nrf2 may prevent biochemical dysfunction and related functional responses of endothelial cells induced by hyperglycemia in which increased expression of transketolase has a pivotal role.”

(Transkelotase, is a key enzyme that changes potentially damaging glucose byproducts into harmless compounds for safe elimination.)

In a separate statement, Thornalley said that the study:

“Suggests that compounds such as sulforaphane from broccoli may help counter processes linked to the development of vascular disease in diabetes. “

He said he fully expected further studies to show that eating a diet rich in brassicas would be highly beneficial to patients with diabetes.

However, Dr Iain Frame, director of research at the charity Diabetes UK, cautioned that findings based on research done on cells in the lab is a long way from trials in real human subjects. But he was encouraged by the study, and told the BBC that it was good to see that:

“Professor Thornalley and his team have identified a potentially important substance that may protect and repair blood vessels from the damaging effects of diabetes.”

Frame said it could also support the idea that eating brocolli is good for you.

“Activation of NF-E2-related factor-2 reverses biochemical dysfunction of endothelial cells induced by hyperglycemia linked to vascular disease.”
Mingzhan Xue, Qingwen Qian, Adaikalakoteswari Antonysunil, Naila Rabbani, Roya Babaei-Jadidi, and Paul J. Thornalley
Diabetes published online on August 4, 2008, as db06-1003

Click here for Abstract.

Sources: University of Warwick, journal abstract.

Written by: Catharine Paddock, PhD