There are many that argue, on philosophical grounds often, that processed food should be avoided. Nature recently published an article that found “even relatively low concentrations of two commonly-used emulsifiers frequently found on processed food ingredient labels — carboxymethylcellulose[E466] and polysorbate-80[E433] — both have been found to induce low-grade inflammation and obesity/metabolic syndrome in wild-type hosts and to promote “robust” colitis in mice with a predisposition to that disorder.” [Link] 
“Carboxymethylcellulose induces bacterial overgrowth and small bowel inflammation in susceptible animals. Because of its ubiquity in products and its unrestricted use in food of the industrial world, CMC is an ideal suspect to account for the rise of IBD in the 20th century.”
Note: ” CMC is one of the important raw material in the toothpaste production, it can mix liquid ingredients with solid materials evenly in the toothpaste” [link] as well as wine and beer, bakery products like breads and cake preparation, ice cream and candy.[Wikipedia].
Polysorbate-80 [Wikipedia] is in ice cream, powdered drink preparations such as hot cocoa mix, and mouthwashes. A small number of people may be sensitive to polysorbate 80,[ 2005 ] and it may be harmful to people with Crohn’s disease.[2013 ]
I view Crohn’s Disease as one of the paths that CFS/IBD/UC can lead to (based on the premise that all are microbiome dysfunctions)
In Europe and America, people eat about 100 mg of polysorbate foods per day on average.
Sorbitol – glucitol
Most of the studies have been on short term impact of oral bacteria and not gut bacteria.
“sorbitol diets exerted a strong influence upon gut microbiota patterns… sorbitol and FOS intake increased L. reuteri cell numbers, and sorbitol also contributed to maintaining the levels of Lactobacillus sp. AD102. Analysis of organic acid concentrations showed that sorbitol intake significantly increased colonic and cecal butyrate levels.”
However, with “Long-term use of xylitol-containing chewing-gum can reduce the growth of… lactobacilli-type bacteria in saliva, even if xylitol is used only on school days. The results also suggest that xylitol gum use can have a long-term, delayed growth-retarding effect on these micro-organisms, since reduced bacterial growth was still observed 15 months following the termination of xylitol use.” 
“Recent studies [of IBS] indicate that a diet restricted in fermentable, poorly absorbed carbohydrates, including fructose, fructans (present in wheat and onions), sorbitol, and other sugar alcohols is beneficial, but confirmatory studies are needed 
“Recently, polymerized forms of fructose (fructans) also were implicated in symptom production in patients with irritable bowel syndrome (IBS). Evidence from uncontrolled and controlled challenge studies suggests that malabsorbed sugars (fructose, sorbitol, lactose) and fructans may act as dietary triggers for clinical symptoms suggestive of IBS.”