The money quote:

The most severe health effects were seen in mice that consumed the chemicals at a level similar to a person whose diet consists of only ice cream.

I wish we would not trouble innocent mice :-( :-( 

They are helping us understand ourselves. 

Yikes:

Artificial preservatives used in many processed foods could increase the risk of inflammatory bowel diseases and metabolic disorders, according to research published on 25 February in Nature1. In a study done in mice, chemicals known as emulsifiers were found to alter the make-up of bacteria in the colon — the first time that these additives have been shown to affect health directly.

About 15 different emulsifiers are commonly used in processed Western foods for purposes such as smoothing the texture of ice cream and preventing mayonnaise from separating. Regulatory agencies such as the US Food and Drug Administration (FDA) rule that emulsifiers are “generally regarded as safe”, because there is no evidence that they increase the risk of cancer or have toxic effects in mammals.

But when immunologist Andrew Gewirtz at Georgia State University in Atlanta and his colleagues fed common emulsifiers carboxymethylcellulose and polysorbate-80 to mice, they found evidence that the chemicals affected the animals' health. Although their diet was not otherwise changed, healthy mice whose water contained the chemicals became obese and developed metabolic problems such as glucose intolerance. In mice genetically engineered to be prone to inflammatory gut diseases, emulsifiers also seemed to increase the severity and frequency with which the animals developed inflammatory bowel disease.

A few Reddit comments:

https://reddit.com/r/science/comments/3l340k/food_preservatives_linked_to_obesity_and_gut/