Scientists in Japan have identified four proteins in chicken legs which appear to be effective in controlling high blood pressure, a study has said. In a paper published in the Journal of Agricultural Chemistry and Food, the researchers said they had extracted collagen from chicken legs and then fed it to hypertensive rats. Collagen is the protein of connective tissue in animals. The rats which were fed collagen had distinctly lower blood pressure levels eight hours afterwards, compared with another group of rats which were fed a saline solution, they wrote. The group of rats fed collagen continued to have significant reduction in blood pressure four weeks later. The study was jointly undertaken by Nippon Meat Packers' Research and Development Center and researchers at the Hiroshima University. Persistent high blood pressure is one of the risk factors for strokes, heart attacks, heart failure and is a leading cause of chronic renal failure. It is believed to be the cause of 4.5 percent of the world's disease burden and is as prevalent in many developing countries as it is in developed nations.