A high-fat diet depletes beneficial bacteria and increases the levels of “bad” bacteria in the oesophagus microbiota, researchers from University of New South Wales have found.

First author Dr Nadeem Kaakoush says two other interesting things were observed:

“The high-fat diet drops the levels of Lactobacillus species, well known to be beneficial and form part of different probiotics. It gives us the idea that maybe we can counteract through probiotics the effects of unhealthy diets and obesity in the oesophagus as they are known risk factors for oesophageal disease. The other interesting observation was the increase of Fusobacterium species given that they have been associated with various diseases."

Fusobacterium has been linked to oral disease like periodontitis, as well as appendicitis, inflammatory bowel diseases and, more recently, colorectal cancers.

Oesophageal Cancers

Now, Dr Kaakoush says, researchers have a reason to look more closely at whether they also play a role in oesophageal adenocarcinoma, and what’s known as the “cascade” of conditions that precede it.

Gastro-oesophageal reflux disease (GORD) occurs when stomach acid backs up into the oesophagus, over time damaging the oesophagus walls. This can cause the oesophageal cells to be replaced by cells more like acid-resistant intestinal cells, a condition called Barrett’s oesophagus.

Oesophageal cancers are uncommon, occurring in 1300 people in Australia each year. However, the incidence of oesophageal adenocarcinoma is rising.

A previous study from Japan in late 2016 established that Fusobacterium in the oesophagus of oesophageal cancer patients is associated with shorter survival times.

“What we’re interested in now is seeing if we increase the Lactobacillus species in the oesophagus, whether that is beneficial, and if we increase Fusobacterium in the oesophagus, does that have negative consequences?” Kaakoush says. “The other thing is the damage to the lining of the oesophagus, and if we can connect that with the presence of Fusobacterium. That would be a pretty good indicator for us to say these bacteria are involved in this cascade."

The study was supported by a Cancer Institute New South Wales Career Development Fellowship and the National Health and Medical Research Council, Australia.

Nadeem O. Kaakoush, Virginie Lecomte, Christopher A. Maloney & Margaret J. Morris Cross-talk among metabolic parameters, esophageal microbiota, and host gene expression following chronic exposure to an obesogenic diet Scientific Reports 7, Article number: 45753 (2017) doi:10.1038/srep45753

Image: University of New South Wales

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