Beyond affecting host metabolism, the gut microbiota may be able to shape brain function and behaviour through the microbiota-gut-brain axis. A recent study, led by Dr. John Penders, from the Department of Medical Microbiology at Maastricht University Medical Centre (The Netherlands), has found that gut dysbiosis and gastrointestinal complaints in anorexia nervosa patients do not recover after weight gain and/or normalisation of eating behaviour.
The researchers aimed to study the role of gut microbiota in anorexia nervosa (AN) by investigating faecal microbiota and short-chain fatty acids (SCFA) in these patients, along with dietary intake and gastrointestinal complaints, before (n = 55) and after (n = 44) weight gain, in comparison with normal-weight participants (NW, n = 55).
The researchers found profound microbial perturbations in AN patients as compared to NW participants, with higher levels of mucin and protein degrading taxa and members of Clostridium clusters I, XI and XVIII, and reduced levels of carbohydrate utilising taxa, including the butyrate-producing Roseburia spp. Interestingly, the restrictive and binge/purging AN-subtypes featured distinct alterations in microbial community compositions. Short-chain fatty acids (SCFAs, including acetate, propionate, and butyrate)–end products of carbohydrate fermentation in the colon– were normal in AN patients.
Some upper and lower gastrointestinal symptoms improved in the course of weight gain whereas others did not. The concentrations of branched chain fatty acids (BCFA, consisting of isobutyrate and isovalerate)–products of protein fermentation–were increased before and after weight gain when compared to NW participants.
To sum up, the gut microbiota and BCFAs of AN patients are altered in comparison to NW participants and neither the dysbiosis, BCFA profiles, nor gastrointestinal complaints recovered after weight gain.
Mack I, Cuntz U, Grämer C, et al. Weight gain in anorexia nervosa does not ameliorate the faecal microbiota, branched chain fatty acids profiles, and gastrointestinal complaints. Sci Rep. 2016; 6:26752. doi:10.1038/srep26752.