Obesity, bariatric surgery and oxidative stress

Nitrate-Nitrite-Nitric Oxide Pathway, Oxidative Stress, and Fertility Outcomes in Morbidly Obese Women Following Bariatric Surgery: A Systematic Review

Obesity reduces nitric oxide (NO) production due to endothelial nitric oxide synthase (eNOS) dysfunction, resulting in oxidative stress, mitochondrial dysfunction, and chronic inflammation. These factors have a negative impact on reproductive health, including oocyte quality, endometrial receptivity, and embryo implantation. When oxidative stress affects eNOS function, the nitrate-nitrite-nitric oxide (NO3-NO2-NO) pathway provides an alternate route for NO production. Bariatric surgery has been found to restore NO production, reduce oxidative stress, and improve fertility in morbidly obese women. This review investigates the molecular mechanisms by which bariatric surgery affects eNOS activity, the NO3-NO2-NO pathway, and oxidative stress reduction, with an emphasis on intracellular activities including mitochondrial biogenesis and NO production. A systematic review employing PRISMA criteria included articles published between 2000 and 2024 from PubMed, Scopus, and Embase that investigated NO3-NO2 pathways, oxidative stress markers, hormonal alterations, and reproductive outcomes in morbidly obese women following bariatric surgery. After evaluating 1542 studies, 11 were selected for the final analysis. Results showed a 45% increase in NO3-NO2 levels (p < 0.001), a 35% reduction in oxidative stress indicators (p < 0.01), a 60% increase in pregnancy rates, and a 50% increase in spontaneous ovulation rates following surgery. These benefits were connected to improved mitochondrial function and endometrial receptivity as a result of reduced oxidative stress and inflammation. The NO3-NO2-NO route is critical in compensating for lower NO generation under oxidative stress and hypoxia, and bariatric surgery significantly improves this pathway to optimize blood flow, mitochondrial function, and reproductive results.

Oxidative Stress Responses in Obese Individuals Undergoing Bariatric Surgery: Impact on Carcinogenesis

Obesity is a big public health problem that claims several thousand lives every year. Bariatric surgery has arisen as a suitable procedure for treating obesity, particularly morbid obesity. Oxidative stress, genotoxicity, apoptosis, and inflammatory responses are recognized as the most important occurrences in carcinogenesis, as they actively contribute to the multistep process. This study aimed to briefly review the connection between oxidative stress, genotoxicity, apoptosis, and inflammation in obese patients undergoing bariatric surgery, focusing on its impact on carcinogenesis. Regarding oxidative stress, bariatric surgery may inhibit the synthesis of reactive oxygen species. Moreover, a significant reduction in the inflammatory status after weight loss surgery was not observed. Bariatric surgery prevents apoptosis in several tissues, but the maintenance of low body weight for long periods is mandatory for mitigating DNA damage. In conclusion, the association between bariatric surgery and cancer risk is still premature. However, further studies are yet needed to elucidate the real association between bariatric surgery and a reduced risk of cancer.

A Systematized Review of the Relationship Between Obesity and Vitamin C Requirements

Obesity rates have increased globally in recent decades. Body weight is used as a modifiable factor in determining vitamin requirements. Accordingly, vitamin C requirements are volumetrically scaled from data for healthy weight males to other age- and sex-based categories. Likewise, it is possible that increases in body weight due to obesity may affect vitamin C needs. A systematized literature review was performed to summarize evidence on whether obesity affects vitamin C intake or status. The literature was also scanned for potential mechanisms for the relationship. Many observational studies showed that vitamin C status is lower in overweight and obese children and adults; this may be explained by lower vitamin C intakes. Nevertheless, a reanalysis of carefully conducted intervention studies has demonstrated a lower vitamin C status in participants who were overweight or obese when given the same dose of vitamin C as subjects of normal weight. Several mechanisms have been proposed to potentially explain why vitamin C status is lower in people with obesity: changes in vitamin C partitioning between lean and adipose tissue, volumetric dilution, metabolic alterations due to obesity, and gut microbial dysbiosis. Depletion-repletion or pharmacokinetic studies that include individuals of diverse body weights and ages would be helpful to further investigate whether obesity increases requirements for vitamin C. The current evidence base supports a lower vitamin C status in people who are overweight or obese; however, the association may be attenuated by lower vitamin C intakes.

Oxidative Stress in Postbariatric Patients: A Systematic Literature Review Exploring the Long-term Effects of Bariatric Surgery

Background

The present study investigates the impact of oxidative stress after bariatric surgery in patients with obesity. This field of study has gained great interest in recent years due to the role that oxidative stress plays in metabolic diseases. Obesity, by itself, can generate an increase in reactive oxygen and nitrogen species, intensifying cellular damage and promoting the progression of adverse metabolic conditions. In this context, bariatric surgery emerges as a candidate capable of modifying oxidative stress biomarkers, facilitating the patient's metabolic recovery.

Methods

A systematic review was carried out, identifying 30 studies found in databases such as PubMed, Scopus, Web of Science, and Google Scholar. It looked at the link between oxidative stress and recovery after bariatric surgery in patients. The selection of studies was based on the measurement of oxidative stress biomarkers before and after surgical intervention.

Results

The results reveal a significant decrease in oxidative stress biomarkers after bariatric surgery. However, a notable variability in antioxidant activity is observed between different patients, as well as a significant influence of comorbidities.

Conclusions

Bariatric surgery is postulated as an effective intervention in reducing oxidative stress in patients with obesity, enhancing antioxidant activity and improving patient recovery. This finding highlights the importance of considering oxidative stress management as an integral part of postoperative care, suggesting the need to implement complementary treatment strategies to optimize health outcomes.

The role of IGF-1 in exercise to improve obesity-related cognitive dysfunction

Obesity is an important factor that threatens human health. The occurrence of many chronic diseases is related to obesity, and cognitive function decline often occurs with the onset of obesity. With the further prevalence of obesity, it is bound to lead to a wider range of cognitive dysfunction (ORCD). Therefore, it is crucial to suppress ORCD through intervention. In this regard, exercise has been shown to be effective in preventing obesity and improving cognitive function as a non-drug treatment. There is sufficient evidence that exercise has a regulatory effect on a growth factor closely related to cognitive function-insulin-like growth factor 1 (IGF-1). IGF-1 may be an important mediator in improving ORCD through exercise. This article reviews the effects of obesity and IGF-1 on cognitive function and the regulation of exercise on IGF-1. It analyzes the mechanism by which exercise can improve ORCD by regulating IGF-1. Overall, this review provides evidence from relevant animal studies and human studies, showing that exercise plays a role in improving ORCD. It emphasizes the importance of IGF-1, which helps to understand the health effects of exercise and promotes research on the treatment of ORCD.

Differential effects of bariatric surgery and caloric restriction on hepatic one-carbon and fatty acid metabolism

Weight loss interventions, including dietary changes, pharmacotherapy, or bariatric surgery, prevent many of the adverse consequences of obesity, and may also confer intervention-specific benefits beyond those seen with decreased weight alone. We compared the molecular effects of different interventions on liver metabolism to understand the mechanisms underlying these benefits. Male rats on a high-fat, high-sucrose diet underwent sleeve gastrectomy (SG) or intermittent fasting with caloric restriction (IF-CR), achieving equivalent weight loss. The interventions were compared to ad-libitum (AL)-fed controls. Analysis of liver and blood metabolome and transcriptome revealed distinct and sometimes contrasting metabolic effects between the two interventions. SG primarily influenced one-carbon metabolic pathways, whereas IF-CR increased de novo lipogenesis and glycogen storage. These findings suggest that the unique metabolic pathways affected by SG and IF-CR contribute to their distinct clinical benefits, with bariatric surgery potentially influencing long-lasting changes through its effect on one-carbon metabolism.

Oxidative Stress and DNA Damage Markers in Colorectal Cancer

Oxidative stress (OS) and inflammation are known to play an important role in chronic diseases, including cancer, and specifically colorectal cancer (CRC). The main objective of this study was to explore the diagnostic potential of OS markers in patients with CRC, which may translate into an early diagnosis of the disease. To do this, we compared results with those in a group of healthy controls and assessed whether there were significant differences. In addition, we explored possible correlations with the presence of tumors and tumor stage, with anemia and with inflammatory markers used in clinical practice. The study included 80 patients with CRC and 60 healthy controls. The following OS markers were analyzed: catalase (CAT), reduced glutathione (GSH) and oxidized glutathione (GSSG) in serum; and 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) and F2-isoprotanes in urine (F2-IsoPs). Tumor markers (CEA and CA 19.9), anemia markers (hemoglobin, hematocrit and medium corpuscular volume) and inflammatory markers (leukocytes, neutrophils, N/L index, platelets, fibrinogen, C-reactive protein, CRP and IL-6) were also determined. Comparison of means between patients and controls revealed highly significant differences for all OS markers, with an increase in the prooxidant markers GSSG, GSSG/GSH ratio, 8-oxodG and F2-IsoPs, and a decrease in the antioxidant markers CAT and GSH. Tumor and inflammatory markers (except CRP) correlated positively with GSSG, GSSG/GSH ratio, 8-oxodG and F2-IsoPs, and negatively with CAT and GSH. In view of the results obtained, OS markers may constitute a useful tool for the early diagnosis of CRC patients.

Lipid Peroxidation in Obesity: Can Bariatric Surgery Help?

Obesity and chronic oxidative stress, often being associated with each other in a vicious circle, are important factors of chronic diseases. Although it was usually considered to accompany aging and wealth, global trends show the increase in obesity among children even in Third World countries. Being manifested by an imbalance between energy consumption and food intake, obesity is characterized by an excessive or abnormal fat accumulation, impaired redox homeostasis and metabolic changes often associated with the self-catalyzed lipid peroxidation generating 4-hydroxynonenal, pluripotent bioactive peroxidation product of polyunsaturated fatty acids. Conservative methods targeting obesity produced only modest and transient results in the treatment of morbid obesity. Therefore, in recent years, surgery, primarily bariatric, became an attractive treatment for morbid obesity. Since adipose tissue is well known as a stress organ with pronounced endocrine functions, surgery results in redox balance and metabolic improvement of the entire organism. The source of bioactive lipids and lipid-soluble antioxidants, and the complex pathophysiology of lipid peroxidation should thus be considered from the aspects of personalized and integrative biomedicine to treat obesity in an appropriate way.

Changes in the expression of meteorin-like (METRNL), irisin (FNDC5), and uncoupling proteins (UCPs) after bariatric surgery

OBJECTIVE

Bariatric surgery is currently the most effective treatment for severe obesity. This study aims to investigate the changes in expression levels of meteorin-like protein (METRNL), irisin (FNDC5), and uncoupling proteins (UCP) 1/2/3 following bariatric surgery to understand their involvement in enhancing metabolism after surgery.

METHOD

A total of 40 participants were enrolled in this interventional study, 20 with obesity BMI ≥ 35 kg/m² and 20 with BMI ≤ 25 kg/m² . Bariatric surgery (laparoscopic sleeve gastrectomy and Roux-en-Y gastric bypass) was performed. The levels of various molecules of interest were analyzed before and after surgery.

RESULTS

Gene expression analysis revealed significantly higher levels of METRNL, UCP1, and UCP3 in individuals with obesity when compared with healthy individuals before surgery (p < 0.05). Gene expression levels of METRNL and UCP2 showed a significant increase after bariatric surgery (p < 0.05). METRNL plasma level was significantly higher in individuals with obesity before surgery (mean [SEM], 55,222.6 [1,421.1] pg/mL, p = 0.0319), as well as at 6 and 12 months (57,537.3 [1,303.9] pg/mL, p = 0.0005; 59,334.9 [1,214.3] pg/mL, p < 0.0001) after surgery.

CONCLUSION

The changes in the levels of various molecules of interest support their possible involvement in the inflammatory and thermogenic responses following bariatric surgery.

Gut microbiota in bariatric surgery

Gut microbes share a symbiotic relationship with humans and perform several metabolic and physiological functions essential for human survival. It has been established in several scientific studies that obesity and other metabolic complications are always associated with disturbed gut microbiota profile, also called gut dysbiosis. In recent years, bariatric surgery has become a treatment of choice for weight loss, and it forms an important part of obesity management strategies across the globe. Interestingly, bariatric surgery has been shown to alter gut microbiota profile and synthesize short-chain fatty acids by gut microbes. In other words, gut microbes play a crucial role in better clinical outcomes associated with bariatric surgery. In addition, gut microbes are important in reducing weight and lowering the adverse events post-bariatric surgery. Therefore, several prebiotics, probiotics and postbiotics are recommended for patients who underwent bariatric surgery procedures for better clinical outcomes. The present review aims to understand the possible association between gut microbes and bariatric surgery and present scientific evidence showing the beneficial role of gut microbes in improving therapeutic outcomes of bariatric surgery.

Telomere length in patients with obesity submitted to bariatric surgery: A systematic review

BACKGROUND

Patients with obesity show evidence of increased levels of inflammation, oxidative stress and premature ageing. Telomere length (TL) is a key marker of cellular ageing, and patients with obesity often present shorter TL. Bariatric surgery (BS) is currently the most effective treatment for severe obesity. The aim of this systematic review was to explore whether the beneficial health effects observed after surgery in obese patients correspond to a restoration in TL or slower rates of shortening. As a secondary aim, we evaluated, at baseline and post-surgery, the relationship between TL and different factors that could play a role in TL changes along time.

METHODS

Searches for relevant articles were performed in MEDLINE, Web of Knowledge and SCOPUS. Prospective longitudinal studies that evaluated leukocyte TL in adult patients who had undergone BS were included. Data were extracted and evaluated by two independent researchers. The protocol was registered in PROSPERO with the number CRD42020197711.

RESULTS

Seven studies based on independent samples that fulfilled our inclusion criteria were included. Obese patients showed shorter telomeres compared to healthy individuals. Long-term studies (>2 years) seem to suggest an improvement in TL after surgery presumably due to the improvement of the inflammatory and oxidative levels of the patients induced by weight loss.

CONCLUSION

Studies seem to point towards a beneficial long-term effect of BS on TL recovery. However, the scarce number of studies and the heterogeneity in the variables analysed in the different cohorts make it difficult to draw a firm conclusion. More studies are needed to evaluate long-term changes to TL following BS.

Association Between Magnesium and Oxidative Stress in Patients with Obesity

Background:

The role of minerals in preventing the generation of oxidative stress in obese individuals has been evaluated. Magnesium is an antioxidant nutrient and a cofactor of enzymes involved in the cell membrane stabilization, attenuating the effects of oxidative stress.

Objective:

To evaluate the association between magnesium and concentrations of thiobarbituric acid reactive substances (TBARS) in patients with obesity and eutrophic women.

Methods:

A cross-sectional study was conducted with 73 women, divided into two groups: case group (patients with obesity, n=27) and control group (eutrophic women, n=46). Measurements of body mass index and waist circumference were performed. Dietary magnesium intake was assessed by the three-day food record using the NutWin software. Urinary magnesium concentration was measured by atomic absorption spectrophotometry method. Plasma concentrations of thiobarbituric acid reactive substances (TBARS) were also determined.

Results:

Mean values of dietary magnesium intake were 161.59 ± 60.04 and 158.73 ± 31.96 for patients with obesity and control group, respectively, with no significant difference between the groups studied (p >0.05). The value of urinary excretion of magnesium was lower than the reference values in both groups, with no significant difference between the groups studied (p >0.05). The plasma concentration of thiobarbituric acid reactive substances was significantly higher in patients with obesity compared to the control group (p <0.001). There was no correlation between levels of magnesium biomarkers and the concentration of TBARS (p >0.05).

Conclusion:

Patients with obesity showed a reduced dietary magnesium intake which seems to induce hypomagnesuria as a compensatory mechanism. The marker of oxidative stress evaluated in this study was not influenced by magnesium.

One Anastomosis Gastric Bypass Reconstitutes the Appropriate Profile of Serum Amino Acids in Patients with Morbid Obesity

Bariatric surgery leads to metabolic benefits in patients with obesity, but their mechanisms are not well understood. The appropriate composition of serum amino acids (AA) is important for sufficient supply of these components into various tissues and organs. Obesity leads to alterations in serum AA concentrations. The aim of this study was to examine the effect of one anastomosis gastric bypass (OAGB), a promising type of bariatric surgery, on serum AA concentrations, which were assayed by LC-MS in serum of 46 bariatric patients prior to and 6–9 months after OAGB, as well as in 30 lean control subjects. The results were analyzed by principle components analysis and metabolic pathway analysis. PCA analysis showed that OAGB led to normalization of serum AA concentrations of patients with obesity to a pattern similar to the control subjects, and the concentrations of essential AA remained decreased after OAGB. Changes of individual AA and their associated metabolic pathways were also presented. OAGB caused normalization of the AA profile, which may contribute to improvement of glucose homeostasis and reduction of cardiovascular risk. Considering decreased essential AA concentrations after OAGB, increased intake of high protein food should be recommended to the patients after this type of bariatric surgery.

Interplay between the Adaptive Immune System and Insulin Resistance in Weight Loss Induced by Bariatric Surgery

Low-grade chronic inflammation plays a pivotal role among other pathophysiological mechanisms involved in obesity. Innate and adaptive immune cells undergo systemic proinflammatory polarization that gives rise to an increased secretion of proinflammatory cytokines, which in turn leads to insulin resistance. Bariatric surgery is currently the most effective treatment for obesity, as it brings on significant weight loss, glucose metabolism improvement, and a decrease in systemic inflammation biomarkers. After bariatric surgery, several changes have been reported to occur in adaptive immunity, including reduction in CD4+ and CD8+ T cell counts, a decrease in the Th1/Th2 ratio, an increase in B regulatory cells, and reduction in proinflammatory cytokine secretion. Overall, there seems to be a major shift in several lymphocyte populations from a proinflammatory to an anti-inflammatory phenotype. Furthermore, increased antioxidant activity and reduced lipid and DNA oxidation products have been reported after bariatric surgery in circulating mononuclear cells. This paper highlights the shift in the adaptive immune system in response to weight loss and improved insulin sensitivity, as well as the interplay between immunological and metabolic adaptations as a result of bariatric surgery. Finally, based on data from research, we propose several mechanisms such as changes in adaptive immune cell phenotypes and their by-products, recruitment in adipose tissue, reduced oxidative stress, and modification in metabolic substrate availability as drivers to reduce low-grade chronic inflammation after bariatric surgery in severe obesity.

Decreased Chromosomal Damage in Lymphocytes of Obese Patients After Bariatric Surgery

The number of bariatric surgeries being performed worldwide has markedly risen. While the improvement in obesity-associated comorbidities after bariatric surgery is well-established, very little is known about its impact on cancer risk. The peripheral lymphocyte micronucleus test is a widely used method for the monitoring of chromosomal damage levels in vivo, and micronucleus frequency positively correlates with cancer risk. Therefore, the aim of this study was to compare the micronucleus frequency before and after bariatric surgery in obese subjects. Peripheral blood mononuclear cells were collected from 45 obese subjects before and at two time-points after bariatric surgery (6 and 12 months) to assess spontaneous micronucleus frequency. Consistent with the increased cancer risk previously shown, bariatric surgery-induced weight loss led to a significant reduction in lymphocyte micronucleus frequency after 12 months. Interestingly, comorbidities such as type 2 diabetes mellitus and metabolic syndrome further seemed to have an impact on the lymphocyte micronucleus frequency. Our findings may indicate a successful reduction of cancer risk in patients following weight loss caused by bariatric surgery.

Key Clinical Factors Predicting Adipokine and Oxidative Stress Marker Concentrations among Normal, Overweight and Obese Pregnant Women Using Artificial Neural Networks

Maternal obesity has been related to adverse neonatal outcomes and fetal programming. Oxidative stress and adipokines are potential biomarkers in such pregnancies; thus, the measurement of these molecules has been considered critical. Therefore, we developed artificial neural network (ANN) models based on maternal weight status and clinical data to predict reliable maternal blood concentrations of these biomarkers at the end of pregnancy. Adipokines (adiponectin, leptin, and resistin), and DNA, lipid and protein oxidative markers (8-oxo-2′-deoxyguanosine, malondialdehyde and carbonylated proteins, respectively) were assessed in blood of normal weight, overweight and obese women in the third trimester of pregnancy. A Back-propagation algorithm was used to train ANN models with four input variables (age, pre-gestational body mass index (p-BMI), weight status and gestational age). ANN models were able to accurately predict all biomarkers with regression coefficients greater than R² = 0.945. P-BMI was the most significant variable for estimating adiponectin and carbonylated proteins concentrations (37%), while gestational age was the most relevant variable to predict resistin and malondialdehyde (34%). Age, gestational age and p-BMI had the same significance for leptin values. Finally, for 8-oxo-2′-deoxyguanosine prediction, the most significant variable was age (37%). These models become relevant to improve clinical and nutrition interventions in prenatal care.