Role of the Microbiota in Obesity: Effect After Bariatric Surgery
NCT ID: NCT07277465
Last Updated: 2025-12-18
Study Results
The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.
Basic Information
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COMPLETED
NA
60 participants
INTERVENTIONAL
2021-03-03
2025-05-31
Brief Summary
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However, in cases of severe obesity, recent data have challenged the prevailing view, as bacterial species associated with low microbial richness (prior to surgery) appear to change only marginally after bariatric surgery, despite significant metabolic improvements.
Our objective is to examine whether gut microbiota and gastrointestinal peptides are further impaired in severe obesity and, additionally, to explore how the microbiota relates to metabolic profile or sex, as well as whether bariatric surgery may differentially correct obesity-related intestinal microbial features.
To this end, we propose a prospective, interventional, translational clinical study involving a cohort of 60 obese patients (BMI \> 35 kg/m²) undergoing laparoscopic gastric bypass surgery. Patients will be grouped according to their degree of obesity to assess potential baseline differences and to evaluate the efficacy of the intervention. Furthermore, we will investigate whether these parameters differ according to metabolic profile or sex.
Body composition and nutritional status will be assessed, along with cardiovascular risk factors and comorbidities (hypertension, obstructive sleep apnea syndrome, dyslipidemia, type 2 diabetes mellitus, and insulin resistance). Gastrointestinal hormones (ghrelin, GIP, GLP-1, PYY, CCK, and leptin) will be measured in serum using Luminex XMAP technology. The content and diversity of the gut microbiota will be analyzed (16S rRNA amplicon sequencing and shotgun metagenomic sequencing using Illumina MiSeq technology) in stool samples collected before and 6-12 months after surgery. Additionally, individualized dietary follow-up and assessment of participants' quality of life will be conducted.
Detailed Description
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To address these gaps, the investigators designed a prospective, interventional, comparative, and translational clinical study including 60 obese individuals scheduled for bariatric surgery at a single tertiary hospital. Participants will be consecutively recruited according to strict inclusion and exclusion criteria and classified by degree of adiposity (severe, morbid, or extreme obesity), metabolic phenotype (metabolically healthy or metabolically abnormal obesity), and sex.
Prior to the surgical intervention, a structured dietary protocol will be implemented. Participants will receive an individualized hypocaloric diet tailored to nutritional requirements, with a macronutrient distribution of 55% carbohydrates, 30% fats, and 15% proteins. During the two weeks preceding surgery, a very low-calorie diet based on Optisource® sachets will be administered in three daily intakes. Postoperative dietary progression will follow standardized clinical guidelines, with close monitoring to support weight reduction and metabolic stabilization. Follow-up evaluations will occur at 1, 6, and 12 months after surgery.
All participants will undergo comprehensive baseline and longitudinal assessments, including: evaluation of nutritional status; anthropometric measurements; body composition and basal metabolism; cardiovascular risk factors; metabolic comorbidities; and exclusion of secondary causes of obesity. Analytical parameters will include fasting plasma glucose, lipid profile (triglycerides, HDL-cholesterol), blood pressure, markers of hepatic and renal function, and additional biochemical indices relevant to obesity and T2DM risk stratification. Gut microbiota profiling will be conducted to evaluate microbial composition, diversity, and gene richness. Gastrointestinal hormone analyses will quantify circulating incretins and appetite-regulating peptides, including GLP-1, PYY, and ghrelin, to explore their association with postoperative metabolic outcomes. Oxidative stress and inflammatory parameters will be also assessed in order to stratify cardiovascular risk before and after induced weight loss after bariatric surgery.
Statistical analyses will be performed using SPSS 17.0. Categorical variables will be summarized with frequency distributions and percentages. Quantitative variables will be described using mean, range, and standard deviation, with normality assessed via the Kolmogorov-Smirnov test. Between-group comparisons (sex, metabolic phenotype) will employ unpaired t-tests or Mann-Whitney U tests; comparisons across obesity categories will use ANOVA. Longitudinal changes following surgery will be evaluated with repeated measures ANOVA or paired t-tests. Correlations will be analyzed using Pearson or Spearman methods, and logistic regression models will be developed to identify predictive factors for specific metabolic responses.
This study aims to determine whether gut microbiota alterations are directly linked to metabolic abnormalities across obesity phenotypes and whether bariatric surgery elicits differential microbial and hormonal responses according to degree of adiposity and sex. It further explores whether gastrointestinal peptides and other peripheral biomarkers can refine obesity phenotyping and enhance individualized clinical management.
Conditions
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Keywords
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Study Design
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NA
SINGLE_GROUP
TREATMENT
NONE
Study Groups
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Bariatric surgery in patients with obesity
Patients will undergo bariatric surgery if they meet the inclusion criteria and are willing to participate in the study.
Bariatric surgery
Bariatric surgery according to surgeon's assessment.
Interventions
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Bariatric surgery
Bariatric surgery according to surgeon's assessment.
Other Intervention Names
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Eligibility Criteria
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Inclusion Criteria
* Aged between 18 and 65 years.
* Patients with a known duration of obesity exceeding five years, despite dietary interventions and farmacological treatment.
Exclusion Criteria
18 Years
65 Years
ALL
No
Sponsors
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Celia Bañuls
OTHER
Responsible Party
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Celia Bañuls
Principal Investigator
Locations
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FISABIO
Valencia, , Spain
Countries
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References
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Nijhawan S, Richards W, O'Hea MF, Audia JP, Alvarez DF. Bariatric surgery rapidly improves mitochondrial respiration in morbidly obese patients. Surg Endosc. 2013 Dec;27(12):4569-73. doi: 10.1007/s00464-013-3125-y. Epub 2013 Aug 24.
Akalestou E, Miras AD, Rutter GA, le Roux CW. Mechanisms of Weight Loss After Obesity Surgery. Endocr Rev. 2022 Jan 12;43(1):19-34. doi: 10.1210/endrev/bnab022.
Ciobarca D, Catoi AF, Copaescu C, Miere D, Crisan G. Bariatric Surgery in Obesity: Effects on Gut Microbiota and Micronutrient Status. Nutrients. 2020 Jan 16;12(1):235. doi: 10.3390/nu12010235.
Cani PD, Van Hul M, Lefort C, Depommier C, Rastelli M, Everard A. Microbial regulation of organismal energy homeostasis. Nat Metab. 2019 Jan;1(1):34-46. doi: 10.1038/s42255-018-0017-4. Epub 2019 Jan 7.
Aron-Wisnewsky J, Prifti E, Belda E, Ichou F, Kayser BD, Dao MC, Verger EO, Hedjazi L, Bouillot JL, Chevallier JM, Pons N, Le Chatelier E, Levenez F, Ehrlich SD, Dore J, Zucker JD, Clement K. Major microbiota dysbiosis in severe obesity: fate after bariatric surgery. Gut. 2019 Jan;68(1):70-82. doi: 10.1136/gutjnl-2018-316103. Epub 2018 Jun 13.
Kootte RS, Levin E, Salojarvi J, Smits LP, Hartstra AV, Udayappan SD, Hermes G, Bouter KE, Koopen AM, Holst JJ, Knop FK, Blaak EE, Zhao J, Smidt H, Harms AC, Hankemeijer T, Bergman JJGHM, Romijn HA, Schaap FG, Olde Damink SWM, Ackermans MT, Dallinga-Thie GM, Zoetendal E, de Vos WM, Serlie MJ, Stroes ESG, Groen AK, Nieuwdorp M. Improvement of Insulin Sensitivity after Lean Donor Feces in Metabolic Syndrome Is Driven by Baseline Intestinal Microbiota Composition. Cell Metab. 2017 Oct 3;26(4):611-619.e6. doi: 10.1016/j.cmet.2017.09.008.
Sroka-Oleksiak A, Mlodzinska A, Bulanda M, Salamon D, Major P, Stanek M, Gosiewski T. Metagenomic Analysis of Duodenal Microbiota Reveals a Potential Biomarker of Dysbiosis in the Course of Obesity and Type 2 Diabetes: A Pilot Study. J Clin Med. 2020 Jan 29;9(2):369. doi: 10.3390/jcm9020369.
Amabebe E, Robert FO, Agbalalah T, Orubu ESF. Microbial dysbiosis-induced obesity: role of gut microbiota in homoeostasis of energy metabolism. Br J Nutr. 2020 May 28;123(10):1127-1137. doi: 10.1017/S0007114520000380. Epub 2020 Feb 3.
Bouter KE, van Raalte DH, Groen AK, Nieuwdorp M. Role of the Gut Microbiome in the Pathogenesis of Obesity and Obesity-Related Metabolic Dysfunction. Gastroenterology. 2017 May;152(7):1671-1678. doi: 10.1053/j.gastro.2016.12.048. Epub 2017 Feb 10.
Haluzik M, Kratochvilova H, Haluzikova D, Mraz M. Gut as an emerging organ for the treatment of diabetes: focus on mechanism of action of bariatric and endoscopic interventions. J Endocrinol. 2018 Apr;237(1):R1-R17. doi: 10.1530/JOE-17-0438. Epub 2018 Jan 29.
Murphy R, Clarke MG, Evennett NJ, John Robinson S, Lee Humphreys M, Hammodat H, Jones B, Kim DD, Cutfield R, Johnson MH, Plank LD, Booth MWC. Laparoscopic Sleeve Gastrectomy Versus Banded Roux-en-Y Gastric Bypass for Diabetes and Obesity: a Prospective Randomised Double-Blind Trial. Obes Surg. 2018 Feb;28(2):293-302. doi: 10.1007/s11695-017-2872-6.
Pareek M, Schauer PR, Kaplan LM, Leiter LA, Rubino F, Bhatt DL. Metabolic Surgery: Weight Loss, Diabetes, and Beyond. J Am Coll Cardiol. 2018 Feb 13;71(6):670-687. doi: 10.1016/j.jacc.2017.12.014.
Other Identifiers
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CEIm: 8/21
Identifier Type: -
Identifier Source: org_study_id