Genistein is an isoflavone, a plant-based chemical that mimics the effects of oestrogen in the body.

BBC: Soy 'helps manage prostate cancer'

Professor Tse said it was too early to recommend the use of isoflavone supplements.

BBC: Soy may benefit stroke patients

He said the mechanism by which isoflavone produces these changes in FMD were still not completely understood.

BBC: Soy may benefit stroke patients

Isoflavone is a major class of phytoestrogens, naturally occurring chemicals that mimic the effect of the human hormone oestrogen.

BBC: Soy may benefit stroke patients

"Women taking soy isoflavone tablets to alleviate hot flashes and prevent bone loss at the time of menopause might want to reconsider, " she adds.

CNN: Soy no help for bone loss, hot flashes

In the new study, published this week in the "Archives of Internal Medicine, " 248 menopausal women were randomly assigned to receive a placebo pill or 200 milligrams of soy isoflavone supplements per day -- a dose "equivalent to approximately twice the highest intake through food sources in typical Asian diets, " Levis says.

CNN: Soy no help for bone loss, hot flashes