Doctors at the Mayo Clinic are warning that a popular dietary supplement, 5 Hydroxy Tryptophan or 5-HTP, may contain a contaminant suspected in a rare blood disease. And late today, the Food and Drug Administration confirmed the Mayo findings. The study, published in the September issue of "Nature Medicine," reports that Mayo doctors have found the same contaminant in off-the-shelf brands of 5-HTP that they found in a batch of the L-Tryptophan dietary supplement that killed 30 people in 1989. Minnesota Public Radio's Brent Wolfe reports from Rochester.