The research, published in the Journal Molecular Nutrition and Food Research, said that while consuming standard broccoli could also reduce cholesterol, the effect was much greater with the Beneforte variety, most likely due to its higher glucoraphanin content.
The researchers measured blood pressure and plasma lipids before and after the experiment and found that in the first of two studies (involving 37 subjects) there was a 7.1% reduction in LDL cholesterol compared to 1.8% in the standard broccoli group.
In the second involving 93 subjects the reduction was 5.1% compared to 2.5% for normal broccoli.
Glucoraphanin, which is transformed into the bioactive compound sulphoraphane in the body, is thought to work by altering the lipid synthesis signaling pathways away from the production of LDL cholesterol by the mitochondria – cell powerhouses – in our body. Mitochondria convert dietary sugar and fat into energy, but if they receive too much fat or sugar this is converted into cholesterol.
The study was conducted in two parts and involved 130 male and female participants in total aged between 50 and 76 years. All subjects selected had a mild to moderate risk of cardiovascular disease.
Split into two groups, they were given either 400 g of standard broccoli or 400 g of high glucoraphanin broccoli per week for 12 weeks, both frozen and steamed for five minutes.
The Beneforte broccoli contained around 21.6 micromoles per gram (μmol/g) of glucoraphanin while the standard variety contained about 6.9 μmol/g.
They said that the cholesterol-lowering benefits could be even greater with fresh-cooked broccoli.
"The reductions in LDL-C were due to consumption of broccoli that had been blanched and frozen. The blanching process destroys all endogenous plant thioglucosidase activity that is required to convert glucoraphanin to the [...] sulforaphane.
"Thus, it is possible that consuming cooked fresh broccoli [...] may have a more pronounced effect on reducing LDL-C than that reported in the current study."
Beneforte broccoli, which contains two to three times as much glucoraphanin as normal broccoli was developed by two UK publically-funded research institutions, The Institute of Food Research (IFR) and the John Innes Centre in Norwich. The scientists crossed cultivated broccoli with a variety of wild Sicilian brassica.
This new research build on previous IFR findings which showed that Beneforté broccoli could ‘retune’ the metabolic processes that may become imbalanced due to age or lack of exercise. An imbalanced metabolism has been linked with cardiovascular disease, obesity and some cancers.
Source: Journal of Molecular Nutrition and Food Research
Published online ahead of print: 7 April 2015, DOI 10.1002/mnfr.201400863
"A diet rich in high glucoraphanin broccoli reduces plasma LDL cholesterol: evidence from randomised controlled trials"
Authors: Armah, C.N. et al.