So-called superfruits like noni or pomegranate juice may provide a lot of antioxidants but may not be much help in preventing cancer, U.S. researchers say. Dr. David Euhus, a professor of surgery at the University of Texas Southwestern Medical Center in Dallas, and an expert in cancer genetics and risk assessment, says the fruits, marketed by companies for their high nutritional and antioxidant content, have no documented impact on keeping cancer at bay in humans. "There's really no superfood that's been proven to reduce the risk of cancer," Euhus says in a statement. "The antioxidants in clinical trials have not shown an effect on cancer rates." Some animal studies have linked eating certain foods -- such as cauliflower, Brussels sprouts and broccoli -- with cancer reduction. The foods have nutritional content Euhus finds "intriguing" in terms of potential disease-fighting properties but human study results remain inconclusive. To help prevent cancer, Euhus suggests staying away from simple sugars that can raise insulin levels, which have been linked to increased breast cancer rates. However, frequent exercise consistently has been shown to reduce breast cancer rates. Euhus warns fruit is still loaded with natural sugar, so quantities should be limited. "I think of fruit as a dessert and not as a medicine," Euhus says.