The broccoli variety, available in UK supermarkets under the name Beneforte, was bred to contain two to three times more of a naturally occurring compound glucoraphanin.
Working with colleagues at the University of Reading, the researchers led by the Institute of Food Research in UK gave a total of 130 volunteers 400g of the high glucoraphanin broccoli per week to include in their normal diet.
After 12 weeks, they saw the levels of LDL-cholesterol in their blood drop by an average of about 6 per cent. Elevated LDL-cholesterol is a recognised risk factor for heart disease.
Glucoraphanin is thought to work by helping our bodies retune cellular metabolism.
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Mitochondria, the energy centres of the cell, convert sugars and fats into energy. But if they are not working efficiently, or if we overload them with too much fat or sugar, one response is to channel excess into cholesterol.
Glucoraphanin is converted in the body to sulphoraphane, which turns on specific genes that activate our bodies' defences against this happening, rebalancing metabolism away from the production of LDL cholesterol.
As glucoraphanin works by reducing how much our bodies make, eating these foods together is likely to have an additive effect, they said.
The study was published in the journal Molecular Nutrition and Food Research.