(NaturalNews) Non-Hodgkin lymphomas belong to a large group of immune system cancers involving lymphocytes (white blood cells). In 2009, according the National Cancer Institute (NCI) about 65,980 Americans were diagnosed with this form of cancer and almost 20,000 died from the disease. But now scientists at the Mayo Comprehensive Cancer Center in Minnesota think they've found a way to prevent a huge number of these malignancies. The key is a nutrient found in many leafy, green vegetables -- vitamin K.For their study, the first ever to investigate vitamin K and non-Hodgkin lymphoma risk, the Mayo researchers enrolled 603 patients who were newly diagnosed with non-Hodgkin lymphoma as well as 1,007 matched cancer-free research subjects who served as controls. The participants answered a food questionnaire about their usual intake of over 120 food items during the two years before they were diagnosed with cancer or they enrolled in the study as a member of the cancer-free control group. They were also asked about their use of vitamin and mineral supplements.The findings of the study, which were recently announced in Washington, D.C., at the 101st Annual Meeting of the American Association for Cancer Research (AACR), showed that the risk of developing non-Hodgkin lymphoma was slashed dramatically -- by 45 percent -- for the study participants who had the highest vitamin K levels compared to participants with the lowest levels of the vitamin. This association remained even after the Mayo research team investigated factors such as age, sex, education, obesity, smoking, alcohol use and consumption of foods with high amounts of antioxidants.Vitamin K is a fat-soluble vitamin found in certain plants or formed by bacterial synthesis. The Mayo study involved intake of the plant form of vitamin K from diet and/or supplement use. The most common food sources of vitamin K include leaf lettuce and spinach, with smaller amounts found in other vegetables such as onions, bell peppers, asparagus and alfalfa sprouts and some fruits, including strawberries.Consuming a lot of vitamin K was associated with a lower risk of non-Hodgkin lymphoma whether the vitamin came from natural food sources or from supplements. However, very high intakes of vitamin K from supplements did not cause a further reduction in risk."These results are provocative, since they are the first work we have done on the connection between vitamin K and non-Hodgkin lymphoma, and this is a fairly strong protective effect," the study's lead investigator, cancer epidemiologist James Cerhan, M.D., Ph.D., said in a media statement. "Whether the protective effect we observed is due to vitamin K intake, or some other dietary or lifestyle exposure, cannot be definitely assessed in this study Well-known as essential for blood clotting (the name of the vitamin is derived from the German word "Koagulations"), vitamin K has also been found in recent years to be important for other functions in the body, including putting a damper on inflammation and regulating cell growth -- and this might explain its apparent ability to protect from non-Hodgkin lymphoma.