The pilot study used four women, all of whom were breast cancer survivors, and monitored changes in their blood of key molecules involved in the growth of cancer cells. The participants were asked to fast on the day of the tests and had blood samples taken before and after eating a portion of watercress. The scientists found that six hours after they had eaten the leaves, the women experienced a drop in the activity of a molecule called 4E binding protein, which is thought to be involved in helping cancer cells survive.
Laboratory studies also showed that extracts taken from watercress leaves inhibited the growth of breast cancer cells. The findings build on epidemiological studies that have shown people who eat watercress and other vegetables rich in isothiocyanates, such as broccoli and cabbage, are at lower risk of developing cancer.
Hazel Nunn, Cancer Research UK's health information manager, said the current study was too small to draw any firm conclusions.
She added: “Watercress may well have benefits but there's no reason to believe that it should be superior to a generally healthy, balanced diet that is high in fibre, vegetables and fruit and low in red and processed meat, salt, saturated fat and alcohol.”More