We all know that mother's milk is best - and scientists have discovered that it could also be one of the best cancer fighters of them all. Human milk contains a natural substance that appears to kill 40 different types of cancer. The magic ingredient is known as Hamlet (human alpha-lactalbumin made lethal to tumour cells). In one test, people with bladder cancer started to excrete dead cancer cells after taking the substance, which comprises a protein and a fatty acid. But researchers at the University of Gothenburg who made the discovery aren't sure if Hamlet naturally occurs in the milk itself, or if it is produced when the milk is mixed with the acid in a baby's stomach. (Source: PLoS ONE, 2010; 5: e9384).