Oh, My Gut! New insights on the role of the gastrointestinal tract and the gut microbiome in chronic kidney disease-mineral and bone disorder

PURPOSE OF REVIEW

The aim of this review is to highlight recent evidence on the role of the gastrointestinal tract and gut microbiome on chronic kidney disease-mineral bone disorder (CKD-MBD) outcomes, including intestinal phosphorus absorption and sensing, and the effect of gut-oriented therapies.

RECENT FINDINGS

Recent evidence has revealed a complex interplay among mineral metabolism and novel gut-related factors, including paracellular intestinal phosphate absorption, the gut microbiome, and the immune system, prompting a reevaluation of treatment approaches for CKD-MBD. The inhibition of NHE3 limits phosphate transport in the intestine and may lead to changes in the gut microbiome. A study in rats with CKD showed that the supplementation of the fermentable dietary inulin delayed CKD-MBD, lowering circulating phosphorus and parathyroid hormone, reducing bone remodeling and improving cortical parameters, and lowering cardiovascular calcifications. In non-CKD preclinical studies, probiotics and prebiotics improved bone formation mediated through the effect of butyrate facilitating the differentiation of T cells into Tregs, and Tregs stimulating the osteogenic Wnt10b, and butyrate was also necessary for the parathyroid hormone (PTH) bone effects.

SUMMARY

Recent findings support multiple possible roles for gut-oriented therapies in addressing CKD-MBD prevention and management that should be further explored through clinical and translational studies.

The effects of pomegranate consumption on obesity indices in adults: A systematic review and meta-analysis

Evidence supports the potential application of polyphenols as agents against obesity. Pomegranate is one of the fruits that possess a high content of polyphenols. This systematic review and meta-analysis of randomized controlled trials (RCTs) sought to evaluate the effects of pomegranate consumption on obesity indices, including body mass index (BMI), body weight, waist circumference (WC), fat mass (FM), body fat percentage (BFP), and fat-free mass (FFM) in adults. Relevant RCTs were obtained by searching databases, including PubMed, SCOPUS, and Web of Science, up to May 2023. Heterogeneity tests of the included trials were performed using the I 2 statistic. Random effects models were assessed based on the heterogeneity tests, and pooled data were determined as the weighted mean difference with a 95% confidence interval. Pooled analysis of 28 trials revealed that pomegranate consumption led to a significant reduction in body weight (WMD: -1.97, 95% CI: -2.91, -1.03, p < .05), and a significant decrease in BMI (WMD: -0.48, 95% CI: -0.76, -0.20, p < .05) in comparison with the control group. However, there were no significant effects on WC, FM, FFM, and BFP in comparison with the control group. Pomegranate consumption may yield a beneficial effect on body weight and BMI in adults. However, there were no significant effects on WC, FM, FFM, and BFP, by pomegranate consumption. Also, pomegranate consumption can reduce body weight, BMI, WC, and BFP in obese adults. Long-term trials with different doses of pomegranate are needed.

The effects of pomegranate consumption on glycemic indices in adults: A systematic review and meta-analysis

BACKGROUND AND AIM

Epidemiologic studies have shown that type 2 diabetes (T2D) is more prevalent worldwide; therefore, improving glycemic indices to prevent or control T2D is vital. Randomized controlled trials (RCTs) on the effects of pomegranate consumption on glycemic indices have shown inconsistent results. Therefore, we aim to evaluate the impact of pomegranate consumption on fasting blood glucose (FBG), fasting insulin, hemoglobin A1c (HbA1c), and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) in adults.

METHODS

A systematic literature search was performed using electronic databases, including PubMed, Web of Science, and Scopus, up to May 2023 to identify eligible RCTs evaluating the effect of pomegranate consumption on glycemic indices. Heterogeneity tests of the included trials were performed using the I2 statistic. Random effects models were assessed based on the heterogeneity tests, and pooled data were determined as the weighted mean difference with a 95 % confidence interval.

RESULTS

Of 1999 records, 32 eligible RCTs were included in the current study. Our meta-analysis of the pooled findings showed that pomegranate consumption significantly reduced FBG (WMD: -2.22 mg/dL; 95 % CI: -3.95 to -0.50; p = 0.012), fasting insulin (WMD: -1.06 μU/ml; 95%CI: -1.79 to -0.33; p = 0.004), HbA1c (WMD: -0.22 %; 95% CI: -0.43 to -0.01; p = 0.037), and HOMA-IR (WMD: -0.30; 95%CI: -0.61 to -0.00; p = 0.046).

CONCLUSION

Overall, the results demonstrated that pomegranate consumption benefits glycemic indices in adults. However, further research with long-term interventions is required.

PROSPERO REGISTRATION CODE

CRD42023422780.

The effects of purslane consumption on lipid profile and C-reactive protein: A systematic review and dose-response meta-analysis

Earlier investigations into the impact of purslane, Portulaca oleracea, on lipid profile and C-reactive protein (CRP) produced contradictory findings. The effect of purslane consumption on lipid profiles and CRP was assessed in this comprehensive review and meta-analysis. We conducted a thorough literature search in online databases, including PubMed, Scopus, the Cochrane library, and ISI Web of Science to find relevant randomized controlled trials up to June 2023. By incorporating 14 effect sizes from 13 RCTs, we were able to show that purslane consumption significantly decreases serum triglyceride (TG) (WMD: -16.72, 95% CI: -22.49, -10.96 mg/dL, p < .001), total cholesterol (TC) (WMD: -9.97, 95% CI: -19.86, -0.07 mg/dL, p = .048), and CRP (WMD: -1.22, 95% CI: -1.63, -0.80 mg/L, p < .001) levels in patients compared to the control group. In addition, purslane consumption significantly increases high-density lipoprotein (HDL-C) (WMD: 4.09, 95% CI: 1.77, 6.41 mg/dL, p = .001) levels. However, purslane consumption did not affect low-density lipoprotein (LDL-C) levels. According to a suggested optimal dosage, purslane consumption is considered to be safe up to 30 g/day. Purslane consumption can significantly improve cardiovascular health by improving lipid profile and inflammation status.

Insulin resistance surrogate markers and risk of hyperuricemia among patients with and without coronary artery disease: a cross-sectional study

Background

Although emerging evidence emphasizes the associations between both insulin resistance and hyperuricemia with coronary artery disease (CAD) risk, no definite relationship has yet been established. In this respect, time-efficient and affordable methods to estimate insulin resistance (IR) status, and to predict risk of hyperuricemia, are needed. Thus, the goal of this investigation was to examine the associations between IR, as assessed by novel surrogate markers [triglyceride-glucose (TyG) and TyG-body mass index (TyG-BMI)], and risk of hyperuricemia in patients with and without diagnosed CAD.

Methods

This cross-sectional study used data from the medical records of 1,170 patients who were referred to the cardiology outpatient clinic. Medical records, anthropometrics, and serum analytes were determined at the initial visit. Hyperuricemia was defined as serum uric acid ≥ 5.6 mg/dL. IR was estimated through surrogate markers (TyG and TyG-BMI). Multiple regression analysis was performed to assess the relationship between these indices and odds of hyperuricemia among patients with and without CAD.

Results

Overall, 814 angiographically-confirmed CAD cases (mean age (SD) = 52 (8)yrs) were compared with 356 patients without CAD (mean age (SD) = 48 (8)yr). There were positive associations between TyG and TyG-BMI indices and odds of hyperuricemia in CAD patients after controlling for confounders (adjusted odds ratio (aOR) = 1.60; 95%CI: 1.02-2.51; p-value = 0.036; and aOR = 1.83; 95%CI: 1.24-2.70; p-value = 0.002, third tertiles for TYG and TYG-BMI, respectively).

Conclusion

The present findings suggest that higher levels of the IR surrogate markers, TyG and TyG-BMI, are associated with higher odds of hyperuricemia in patients with CAD. However, given the cross-sectional design of this study, the sensitivity and specificity of these novel markers could not be determined for confirming the diagnosis of IR and hyperuricemia, further studies are needed to determine such outcomes and to confirm the current findings.

Dietary Total Antioxidant Capacity and Risk of Polycystic Ovary Syndrome: A Case-Control Study

Among multiple factors that affect the etiology of polycystic ovary syndrome (PCOS), diet has<br />an important contribution. Chronic oxidative stress has also been implicated in the development of PCOS. The<br />present study is an attempt to evaluate dietary total antioxidant capacity (TAC) and its relationship with odds of<br />PCOS in Iran.<br />Materials and Methods: The study was carried out as a case-control study in hospital outpatient clinics, Tehran,<br />Iran. Totally, 310 female participants with a history of PCOS and 602 age-matched controls took part in this<br />study between June 2015 and December 2018. A reproducible and valid 168-item semi-quantitative food frequency<br />inventory was utilized to determine the entire antioxidants of the usual diet in order to calculate dietary<br />TAC. The relationship of dietary TAC with odds of PCOS were assessed adjusting for potential confounders<br />through an estimation of two multivariable conditional regression models. The first tertile was presented as a<br />reference category.<br />Results: In a fully adjusted model, the highest tertile of dietary TAC was associated with a reduced odds of<br />PCOS [odds ratio (OR): 0.81, 95% confidence interval (95% CI): 0.59, 0.96, P for trend: 0.038). In addition, PCOS odds decreased in the highest tertile of α-tocopherol intake (OR: 0.73, 95% CI: 0.56, 0.88, P for trend:<br />0.023). The adjusted ORs in the highest tertile of vitamin C, β-carotene and magnesium were 0.79 (95% CI: 0.83-0.97), 0.81 (95% CI: 0.67-0.98) and 0.91 (95% CI: 0.55-0.9 8) respectively, with a significant trend.<br />Conclusion: Our results provide evidence that there was a relationship between high TAC diets and lower odds of<br />PCOS.

The association between fertility diet score and polycystic ovary syndrome: A Case-Control study

We performed this case-control study with 303 polycystic ovarian syndrome (PCOS) patients and 588 age-matched controls to evaluate the relation between fertility diet score and odds of PCOS. In a fully adjusted model, the top tertile of fertility diet score compared to the bottom was associated with 22% [95%CI 0.71-0.93] lower odds of PCOS (P trend = 0.012). Ratio of monounsaturated to trans fat and vegetable protein was associated with a lower odd of PCOS. Animal protein intake and glycemic load were associated with a higher odd of PCOS. Based on our results, increasing the quality of the diet according to fertility diet score can reduce the odds of PCOS.