Watercress not only adds unusual texture and tang to a salad, it may also contribute an unexpected health benefit. A short-term pilot study by the University of Southampton, UK, indicates that the plant compound phenylethyl isothiocyanate, found in unusually high concentrations in the peppery herb, may help suppress breast cancer by interfering with a protein function that spurs cancer cell development. The compound apparently works to block the signal that a tumor sends out, calling for surrounding normal tissues to grow new blood vessels to feed it, thus starving the tumor of oxygen and nutrients. More research is needed.