Watercress is grown in water and like its veggie cousins, broccoli and kale, watercress is also rich in vitamins K and C. And like other brassica vegetables, watercress contains a potent cancer fighter called sulforaphane. This leafy green also supplies nitrates, which numerous studies have shown help lower blood pressure (and even boost athletic performance if enough is consumed prior to a workout). Dietary nitrates work indirectly to improve blood flow and ultimately more oxygen gets to your muscles. Watercress makes a nutritious addition to spring mix salads, blended into smoothies or stuffed into wraps and sandwiches. - Dr. Liz Applegate