Study leader Joe Alcock of the University of New Mexico and VA Medical Center and colleagues at Northwestern University said the body evolved to recognize these fats to create an immune response to preempt the impeding changes in harmful bacteria. The resulting low-level inflammation over the long-term causes chronic disease such as heart disease, Alcock said.
Some fats -- mostly unsaturated fats found in plants and fish -- have strong anti-microbial properties and react chemically with bacterial cell membranes, weakening them, Alcock said.
"If you expose unsaturated fats on bacteria, the bacteria have a tendency to dissolve. The combination of long chain unsaturated fats, especially omega-3 fatty acids, and innate host defenses like gastric acid and antimicrobial peptides, is particularly lethal to pathogenic bacteria," Alcock said in a statement. "Saturated fats on the other hand generally lack those anti-microbial properties, and in fact can provide a carbon source that bacteria need to grow and flourish."
It may be these differing microbial effects that are at the root of why some fats are inflammatory and some aren't, Alcock said.
However, while this hypothesis is well supported by current data, there's much more research to be done, Alcock warned.
The findings are scheduled to be published in The Quarterly Review of Biology in March.