LONDON (Science) - Around two million years ago, a genetic change occurred that differentiated humans from most other primates that both protected humans from diseases, yet made red meat a health risk.
At this point in human evolution, a certain gene, known as CMAH, that allows for the synthesis of a sugar called Neu5Gc, went missing. This sugar is present in red meats, some fish and dairy products. When humans consume an animal that has that gene, the body has an immune reaction to the foreign sugar, which can cause inflammation, arthritis, and cancer.
University of Nevada, Reno researchers, led by College of Science Assistant Professor David Alvarez-Ponce, have analyzed 322 animal genome sequences from the National Center for Biotechnology Information looking for animals that show the presence of active CMAH genes. They placed the data from the 322 animal genomes into a "tree” to determine when in an animal’s evolutionary history did the CMAH gene became inactive or "turned off.” This is useful in explaining why certain species have an active CMAH gene and why similar species don’t.
The Alvarez-Ponce lab specializes in studying the evolution of genes and genomes using bioinformatics. When it comes to the few fish investigated so far, there is an insignificant concentration of the Neu5Gc sugar to be a medical concern, but the concentrations of Neu5Gc are significantly higher in fish eggs, better known as caviar. As masters’ student Sateesh Peri puts it, "one of the most expensive foods is among the ones with the highest amount of toxic Neu5Gc.”