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isoUDCA bile acid decreases after surgery reducing appetite

Researchers from the University of Nottingham, King's College London, UK and Amsterdam University Medical Center, The Netherlands, has shed light on the molecules underlying the benefits bariatric surgery on patient appetite and metabolism. The research has shown that surgery can significantly alter the levels of bile acid associated with higher appetite, as can taking fibre supplements but to a lesser degree.

Figure 1: Graphical abstract. Credit: Cell Reports Medicine (2023). DOI: 10.1016/j.xcrm.2023.100993

Researchers studied a group of patients in Amsterdam who had undergone bariatric surgery by measuring levels of bile acids before surgery and a year post-operation. They also studied bile acids from two population studies - TwinsUK, run by King's College London, and PREDICT, run by King's College London and nutrition company, ZOE.

The study found that a specific bile acid called isoursodeoxycholate (isoUDCA), which is associated with higher appetite and worse metabolic levels, decreased after bariatric surgery and after taking fibre supplements. Levels of isoUDCA did not decrease after consuming omega-3 supplements.

"Bariatric surgery is not only extremely effective at helping people lose weight by reducing their appetite, but also improves their liver function and their metabolism” explained co-lead author, Professor Ana Valdes from the University of Nottingham's School of Medicine. "What our study shows is that specific microbial metabolite is involved in some of these benefits and that, although to a more modest extent, dietary fibre might mimic some of these effects. This could help design dietary supplementation studies aimed at increasing satiety and improving liver parameters."

By understanding these mechanisms, scientists may be able to develop new interventions that mimic the effects of bariatric surgery without putting patients through the procedure itself. Understanding whether isoUDCA can be modified by lifestyle interventions could lead to more targeted treatments for obesity.

"The study's results have important implications for the development of targeted interventions for metabolic disorders focused on the gut microbiome,” added co-lead author, Dr Cristina Menni from King's College London. "By better understanding the complex interplay between genetics, the gut microbiome, and diet in regulating bile acid levels and their impact on appetite and metabolic health, we may be able to develop new strategies for preventing and treating obesity and metabolic syndrome.”

Another key finding was seeing the strong influence of gut microbes on the levels of isoUDCA. This confirms that the gut microbiome is key to determining the outcomes of bariatric surgery and sheds light on the ways in which gut microbes modify a person's metabolism.

"This study highlights the key role that fibre plays in appetite regulation and metabolism, harnessed by specific gut microbes. Advanced gut microbiome testing (as used by ZOE) provide personalised insights that can support metabolic health,” said co-author, Professor Tim Spector, Professor of Genetic Epidemiology at King's College London and co-founder of ZOE, the personalized nutrition company. “The gut microbiome and its chemical products such as these bile acids hold huge promise for reducing obesity without the need for invasive surgery."

The findings were reported in the paper, 'The secondary bile acid isoursodeoxycholate is associated with postprandial lipaemia, inflammation and appetite, and changes post bariatric surgery', published in Cell Reports Medicine. To access this paper, please click here


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