Immune to our Food

Fast Food, Slow Recovery

Our country is plastered with weight-loss advertisements. For every McDonald’s commercial, there is another one for Lean Cuisine or Weight Watchers. In America, obesity and health have become national concerns, as over a third of the adult population is obese—a record high. It seems that unhealthy eating habits don’t just contribute to obesity; they also have long-term consequences that originate from our immune systems and DNA.

Our immune systems have a memory similar to that of our muscles and brains. For example, our immune systems are able to recognize pathogens such as the influenza virus so that we are capable of fighting possible recurring infections. This evolutionary advantage in humans allows us to ward off infections and illnesses on the daily. Without our innate immune system’s memory, we would die from the common cold.

The Latz lab at University of Bonn, in which postdoctoral fellow Anette Christ has researched the immune system, has delved into these health concerns with a scientific mindset. By pairing a problem we see in society with curiosities about the innate immune system and its response to certain types of diets, the researchers discovered that the immune system responds similarly to the typical Western fast food diet—high in fat, high in sugar, and low in fiber—as it does to pathogens and infections.

The experiment was performed on three groups of mice: one was fed a standard healthy chow diet, a second was fed a Western diet, and a third group was given a Western fast food diet and then switched over to the chow diet after a period of time. After performing genetic analyses on the different groups’ bone marrow cells, the Latz lab discovered the presence of signatures linked to inflammation and immune cell differentiation called inflammasomes that release inflammatory messengers in the group of mice on a Western diet. Inflammasomes are usually only triggered by bacterial infections in order to keep the immune system ready for a subsequent infection. These signatures were originally observed in the group that had switched diets, but they later disappeared after the mice were put onto chow diet. Although still curious about how exactly these signatures recognize characteristics of the Western fast food diet, the lab was surprised to discover that the immune system may treat high-sugar, high-fat foods the way it treats bacterial infections.

Furthermore, they found that the Western fast food diet affects histone-packaging in the DNA, which means that certain portions of the DNA unwind to cause a change in the expression of the genetic material of the cell. These epigenetic changes, coupled with inflammation, have been shown to play a major role in the development of atherosclerosis, diabetes, and heart disease in the mice. This finding suggests that nutrition and diet choices can have major consequences on our health.

The next step in this research is determining whether it applies to humans. In the near future, Christ hopes to conduct a clinical study in which healthy volunteers will be exposed to different diets for several different time periods. While this study will have more variables, she believes that it will produce results similar to those of the study she has already performed with the Latz lab.

As health gurus and health movements are on the rise, we often find ourselves wondering which diets are the best for us: vegan? vegetarian? A raw diet? The answer is probably none of the above. “There is no ‘correct’ diet out there for us,” Christ said. Everyone is different—due to different food resources and traditional cuisines, people from different races or geographical locations may have varied intestinal environments and genetic makeups that complicate the answer. It’s nonetheless important for people to be informed about what types of foods they should choose for themselves in an attempt to live a healthy life. We are what we eat, and our immune systems agree.