"A non-human, cellular molecule is absorbed into human tissues as a
result of eating red meat and milk products, according to a study by
researchers at the University of California, San Diego (UCSD) School of
Medicine, published online the week of September 29, 2003 in Proceedings
of the National Academy of Sciences. The researchers also showed that
the same foreign molecule generates an immune response that could
potentially lead to inflammation in human tissues."

http://www.sciencedaily.com/releases/2003/09/030930055440.htm