A Nobel Prize-winning scientist believes sick cows might be making humans sick. Professor Harald zur Hausen won the Nobel Prize in medicine in 2008 for discovering the link between HPV and cervical cancer, and he now believes that viruses in cows may be linked to colorectal cancer (CRC).
Studies have been done that have linked diets high in red meat to CRC. So far, scientists believed that the link could have been due to the cooking process and carcinogens that are generated when meat is cooked, processed or cured. But these same carcinogens are present when cooking white meat and fish, and zur Hausen believes the link may actually be from beef that's served rare, not well done.
The focus of his work is on TT-viruses that occur frequently in cattle. The hypothesis is that these viruses may remain viable if the meat is served rare. The virus is eliminated completely only when meat is cooked to the "well done" stage.
Japanese and Korean cusine has recently begun to favor very lightly cooked or completely raw beef over the traditional fish-based diet, and a corresponding rise in the rate of CRC has also been observed. On the other hand, countries which are experiencing a rise in the popularity of well-cooked beef, like Saudi Arabia, haven't seen similar rises in CRC rates.
The research is still ongoing and much more data is needed, but it's interesting to note that zur Hausen predicted in the mid-80s that as much as half of all cancers could be linked to viruses. "Any link between this and human cancer is yet to be established, but it seems clear that the search for infectious causes of cancer is only just beginning," zur Hausen said.
In the meantime, it might be better to order that burger well done—just to be on the safe side.