Can curcumin supplementation break the vicious cycle of inflammation, oxidative stress, and uremia in patients undergoing peritoneal dialysis?

BACKGROUND & AIMS: Turmeric (a source of curcumin) is an excellent food to modulate oxidative stress, inflammation, and gut dysbiosis in patients with chronic kidney disease (CKD). However, no studies report the benefits of curcumin in patients undergoing peritoneal dialysis (PD). This study aims to evaluate the effects of curcuminoid supplementation on oxidative stress, inflammatory markers, and uremic toxins originating from gut microbiota in patients with CKD undergoing PD. METHODS: This longitudinal, randomized, single-blind, placebo-controlled trial evaluated 48 patients who were randomized into two groups: Curcumin (three capsules of 500 mg of Curcuma longa extract, with 98.42 % total curcuminoids) or placebo (three capsules of 500 mg of starch) for twelve weeks. In the peripheral blood mononuclear cells (PBMCs), the transcriptional expression levels of Nrf2, HOX-1 and NF-κB were evaluated by quantitative real-time PCR. Oxidative stress was evaluated by malondialdehyde (MDA) and total Thiol (T-SH). TNF-α and IL-6 plasma levels were measured by ELISA. P-cresyl sulphate plasma level, a uremic toxin, was evaluated by high-performance liquid chromatography (HPLC) with fluorescent detection. RESULTS: Twenty-four patients finished the study: 10 in the curcumin group (57.5 ± 11.6 years) and 14 in the placebo group (56.5 ± 10.0 years). The plasma levels of MDA were reduced after 12 weeks in the curcumin group (p = 0.01), while the placebo group remained unchanged. However, regarding the difference between the groups at the endpoint, no change was observed in MDA. Still, there was a trend to reduce the p-CS plasma levels in the curcumin group compared to the placebo group (p = 0.07). Likewise, the concentrations of protein thiols, mRNA expression of Nrf2, HOX-1, NF-κB, and cytokines plasma levels did not show significant changes. CONCLUSION: Curcuminoid supplementation for twelve weeks attenuates lipid peroxidation and might reduce uremic toxin in patients with CKD undergoing PD. This study was registered on Clinicaltrials.gov as NCT04413266.

Sulforaphane Supplementation Did Not Modulate NRF2 and NF-kB mRNA Expressions in Hemodialysis Patients.

BACKGROUND: Patients with chronic kidney disease (CKD) have reduced expression of erythroid nuclear factor-related factor 2 (NRF2) and increased nuclear factor κB (NF-κB). "Food as medicine" has been proposed as an adjuvant therapeutic alternative in modulating these factors. No studies have investigated the effects of sulforaphane (SFN) in cruciferous vegetables on the expression of these genes in patients with CKD. OBJECTIVE: The study aimed to evaluate the effects of SFN on the expression of NRF2 and NF-κB in patients on hemodialysis (HD). DESIGN AND METHODS: A randomized, double-blind, crossover study was performed on 30 patients on regular HD. Fourteen patients were randomly allocated to the intervention group (1 sachet/day of 2.5 g containing 1% SFN extract with 0.5% myrosinase) and 16 patients to the placebo group (1 sachet/day of 2.5 g containing corn starch colored with chlorophyll) for 2 months. After a washout period of 2 months, the groups were switched. NRF2 and NF-κB mRNA expression was evaluated by real-time quantitative polymerase chain reaction, and tumor necrosis factor alpha and interleukin-6 levels were quantified by enzyme-linked immunosorbent assay. Malondialdehyde was evaluated as a marker of lipid peroxidation. RESULTS: Twenty-five patients (17 women, 55 [interquartile range = 19] years and 55 [interquartile range = 74] months on HD) completed the study. There was no significant difference concerning the expression of mRNA NRF2 (P = .915) and mRNA NF-κB (P = .806) after supplementation with SFN. There was no difference in pro-inflammatory and oxidative stress biomarkers. CONCLUSION: 150 µmol of SFN for 2 months had no antioxidant and anti-inflammatory effect in patients with CKD undergoing HD.

Curcumin supplementation improves oxidative stress and inflammation biomarkers in patients undergoing hemodialysis: a secondary analysis of a randomized controlled trial.

BACKGROUND AND OBJECTIVES: Recent studies have shed light on the potential role of curcumin in mitigating inflammation in patients with chronic kidney disease (CKD). This study aimed to evaluate the effects of curcumin supplementation on plasma levels of markers of inflammation and oxidative stress in patients with CKD undergoing hemodialysis (HD). METHODS: These are secondary exploratory analyses from a previous double-blind, randomized controlled pilot study registered under ClinicalTrials.gov Identifier no. NCT00123456. It included 28 hemodialysis patients from a previous study divided into two groups: curcumin group (receiving juice with 2.5 g of turmeric 3×/week for 12 weeks) and a control group. The TNF-α, IL-6 and Ox-LDL plasma levels were measured by sandwich enzyme immunoassays ELISA; lipid peroxidation was measured by the reaction between malondialdehyde (MDA) and thiobarbituric acid. RESULTS: After 12 weeks of supplementation with curcumin, the TNF-α plasma levels were significantly reduced [from 15.0 (8.23-73.3) to 6.17 (1.11-55.0) pg/mL, p = 0.01]. CONCLUSION: 12 weeks of treatment with curcumin in HD patients resulted in a reduction in the biomarker of inflammation (TNF-α), confirming our previous hypothesis that curcumin has an anti-inflammatory effect.

Effect of cranberry supplementation on toxins produced by the gut microbiota in chronic kidney disease patients: A pilot randomized placebo-controlled trial.

BACKGROUND & AIMS: Patients with Chronic Kidney Disease (CKD) have an imbalance in the gut microbiota that can lead to increase levels of lipopolysaccharides (LPS) and uremic toxins such as indoxyl sulfate (IS), p-cresyl sulfate (p-CS), and indole-3 acetic acid (IAA). Among the therapeutic options for modulating gut microbiota are the bioactive compounds such as polyphenols present in cranberry, fruit with potential antioxidant and anti-inflammatory effects. This clinical trial focuses on evaluating the effects of supplementation with a dry extract of cranberry on plasma levels of LPS and uremic toxins in non-dialysis CKD patients. METHODS: It was a randomized, double-blind, placebo-controlled study. Patients were randomized into two groups: the cranberry group received 500 mg of dry cranberry extract (2 times daily), and the placebo group received 500 mg of corn starch (2 times daily) for two months. LPS plasma levels were evaluated by enzyme-linked immunosorbent assay (ELISA) and uremic toxins (IS, p-CS, and IAA) by high-performance liquid chromatography-fluorescence detection. Anthropometric measurements and food intake using the 24-h food recall technique were also evaluated before and after the intervention. RESULTS: Twenty-five participants completed two months of supplementation: 12 patients in the cranberry group (8 women, 56.7 ± 7.5 years, estimated glomerular filtration rate (eGFR) of 39.2 ± 21.9 mL/min); 13 patients in the placebo group (9 women, 58.8 ± 5.1 years, eGFR of 39.7 ± 12.9 mL/min). As expected, there was a negative association between glomerular filtration rate and p-CS and IS plasma levels at the baseline. No change was observed in the uremic toxins and LPS levels. CONCLUSION: Cranberry dry extract supplementation for two months did not reduce the LPS and uremic toxins plasma levels produced by the gut microbiota in non-dialysis CKD patients.

Resistant starch type-2 enriched cookies modulate uremic toxins and inflammation in hemodialysis patients: a randomized, double-blind, crossover and placebo-controlled trial.

BACKGROUND: The aim of this study was to evaluate the effect of resistant starch (RS) enriched cookies supplementation on mRNA expression of nuclear transcription factors (nuclear erythroid 2-related factor, Nrf2; nuclear factor kappa-B, NF-κB), involved with inflammation and on uremic toxins levels produced by the gut microbiota in hemodialysis (HD) patients. METHODS: A randomized, double-blind, placebo-controlled crossover study with 26 HD patients was conducted. The patients were assigned to either resistant starch enriched cookies (16 g of RS per day) or placebo cookies supplementation during the first four weeks. After the washout period, patients were supplemented again, in the form of a crossover, for another 4 weeks. Nrf2, NF-κB, and antioxidant enzymes mRNA expression were measured by rt-PCR and protein expression by western blotting assay from isolated peripheral blood mononuclear cells (PBMC). Oxidative stress and inflammatory biomarkers, as well as uremic toxins, were evaluated. Intention-to-treat analysis was performed, using the proc mixed procedure in SAS. RESULTS: In RS group, post-treatment mean mRNA Nrf2 expression was market increased from baseline values, associated with a high expression of NQO1 protein. Besides, IS plasma levels were reduced in the RS group. No significant difference was observed in the placebo group. CONCLUSION: Our results suggested that resistant starch enriched cookies may be a good nutritional strategy to reduce indoxyl sulfate levels derived from the gut microbiota and also attenuate the inflammation in hemodialysis patients.