It’s not only fat, sugar, salt, and artificial additives that make junk food so dangerous to the heart. New research out of the University of Leicester has identified harmful bacterial molecules in certain processed foods such as burgers and processed meals that are also bad for your ticker.

The study identifies so-called “pathogen-associated molecular patterns” (PAMPs), which are released by certain types of bacteria as they grow during some food processing and refrigeration processes. PAMPs have been shown to increase the risk of developing coronary artery disease and Type 2 diabetes.

“It has been understood for many years that frequent consumption of highly processed foods, particularly processed meats, is associated with increased risk of developing a range of diseases, including cardiovascular disease, Type 2 diabetes and obesity,” said lead researcher Dr. Clett Erridge, from the University's Department of Cardiovascular Sciences.

“Our recent findings have uncovered a potential mechanism by which certain types of processed food increase risk of developing these diseases. In essence, we have discovered that contaminating molecules that arise in processed foods from the overgrowth of a specific type of bacteria during refrigeration or food processing can cause our immune systems to over-react in a manner that might be damaging to health when we eat foods containing these molecules."

To reach their conclusions, researchers tested volunteers on a diet low in PAMPs for one week and discovered an 11 percent reduction in white blood cell counts and an 18 percent reduction in LDL “bad.” Those decreases translate to the equivalent of a 40 percent reduction in risk of developing coronary artery disease.

In addition, the volunteers also experienced a reduction in weight and waist size, which equates to a 15 percent reduction in risk of developing Type 2 diabetes.

When the same volunteers were fed food enriched in PAMPs, the beneficial changes were reversed, highlighting the negative effect PAMPs appear to have on the health of an individual.

“Crucially, we have found that some processed foods do not contain these molecules, and our results suggest it should be possible to manufacture almost any current foodstuff in a manner that results in a low content of pro-inflammatory PAMP molecules,” Dr. Erridge added. “Our method can also be used to monitor progress in efforts to clean up the production process.

"The present work suggests that removing these molecules from common foods could provide a health benefit to consumers and suggest a potential means of making some of our favorite foods healthier without any appreciable change to taste, texture, cost or ingredients."

Key processed foods found to frequently contain high levels of PAMPs include sausages and burgers, ready-to-eat meals (especially lasagna, Bolognese pasta sauce), prepared sauces, sandwiches, cheeses, chocolate, and some types of ready-chopped vegetables, such as onions.

When food is fresh, including any type of meat, fruit or vegetable, it contains undetectable levels of PAMPs, the researchers explained.