Asparagus and other foods like potatoes, nuts, legumes and soy contain a compound known as asparagine, which researchers believe helps drive the spread of breast cancer to other organs. "When scientists reduced asparagine in animals with breast cancer, they found that the number of secondary tumors in other tissues fell dramatically," The Guardian reports. "The spread of malignant cells, often to the bones, lungs and brain, is the main cause of death among patients who are diagnosed with breast cancer." From the report: Asparagine is an amino acid that is made naturally in the body as a building block for proteins. But it is also found in the diet, and in high levels in certain meats, vegetables and dairy products. The international team of cancer specialists from Britain, the U.S., and Canada studied mice with an aggressive form of breast cancer. The mice develop secondary tumors in a matter of weeks and tend to die from the disease within months. Writing in the journal Nature, the researchers describe how they reduced the ability of breast cancer to spread in the animals by blocking asparagine with a drug called L-asparaginase. To a lesser extent, by putting the animals on a low-asparagine diet worked too. Inspired by the results, the scientists examined records from human cancers and found that breast tumors that churned out the most asparagine were most likely to spread, leading patients to die sooner. The same was seen in cancers of the head, neck and kidney.