MedicalResearch.com Interview with: Dr. Clett Erridge PhD Department of Cardiovascular Sciences University of Leicester Clinical Science Wing Glenfield General Hospital Leicester Medical Research: What is the background for this study? What are the main findings? Dr. Erridge: We have spent many years seeking potential stimuli that might be responsible for triggering the chronic inflammatory processes that underpin atherosclerosis. Our earlier work focused mainly on the questions of whether and how various molecules related to lipoprotein particles, oxidised lipids and fatty acids interacted with receptors of the innate immune system, which we believe are central players in the initiation of atherosclerosis. However, we were surprised to discover (as a result of some control experiments that we expected to yield a null result), that extracts of some, but not all, foods trigger inflammatory cytokine production in human monocytes via stimulation of the innate immune receptors Toll-like receptor (TLR)-2 and TLR4. The molecules responsible for triggering these responses (collectively termed PAMPs, 'pathogen-associated molecular patterns'), were found to arise in foods that have been finely chopped and stored at refrigeration temperature or above for some time, as a result of the growth and activity of common food spoilage bacteria. The foods most commonly affected are minced meats, ready chopped vegetables, some cheeses and chocolates. The present study found that in 11 healthy volunteers who habitually consumed food products rich in PAMPs, switching to a low PAMP diet for 7 days resulted in an 18% reduction in LDL-cholesterol, 11% reduction in white blood cell count, a 1.5 cm reduction in waist circumference and a 0.6 kg reduction in body weight. Switching back to a high PAMP diet, in which the same volunteers were then fed meals tested and proven to be high in PAMPs, for just 4 days reversed these beneficial effects. A second study in 13 healthy volunteers then showed that PAMPs can exert effects on white cell markers of inflammation within 24 h of consumption, when volunteers were fed either fresh or processed onion-based meals, which were nutritionally identical other than for content of bacteria and PAMPs. (more…)