There are studies on PubMed which now agree and has implication for CFS/IBS patients

• High cocoa polyphenol rich chocolate may reduce the burden of the symptoms in chronic fatigue syndrome. 2010
• [The composition of the gastrointestinal mucosa-associated microbiota in irritable bowel syndromepatients]. 2013 – less Bifidobacterium in IBS
• My prior post on Bifidobacterium infantis 35624 – a demonstrated probiotic

A reader forward me Chemists discover secret to dark chocolate’s health benefits from the LA times… and behold

What they found was that after cocoa was “digested,” long molecules called polyphenolic polymers remained within the gastrointestinal, or GI, tract. The molecules are too large to cross the walls of the gut and be used as nutrients, according to researcher John Finley, a professor of food science and biochemistry at Louisiana State University. “They do nothing for us except travel down the GI tract after we consume them,” Finley said. That is until they encounter some of the many microbes that inhabit the human colon, particularly Bifidobacterium and lactic acid bacteria, researchers said.

“These little guys say, ‘Hey —   there’s something in there that I can use,’ and they start to break it down,” Finley said.

The smaller molecules that result from this fermentation can travel through the gut wall and be used by the body, researchers said.

“These materials are anti-inflammatory and they serve to prevent or delay the onset of some forms of cardiovascular disease that are associated with inflammation,” Finley said.

So dark chocolate promotes the growth of bifidobacterium (a known undergrowth in CFS), as well as pumping in anti-inflammatory chemicals.

Bottom Line for diet: Take  bifidobacterium and chocolate together!