The association between dietary folate intake and risk of colorectal cancer incidence: A systematic review and dose‒response meta-analysis of cohort studies.

Background: Dietary components can influence the incidence of colorectal cancer (CRC). Folate is one of the compounds that plays an essential role in the formation of DNA structures, which can lead to or prevent tumorigenesis. The present study is the first systematic review and dose-response meta-analysis of cohort studies evaluating the association between dietary folate intake and the risk of CRC. Methods: The PubMed/Medline, Scopus, and ISI Web of Science databases were systematically searched for cohort studies that assessed the association between folate intake and CRC up to January 2024. Summary relative risks (RRs) and 95 % confidence intervals (CIs) were calculated using a random effects model. Also, linear and nonlinear dose-response analyses were conducted for the dose-response associations between folate intake and risk of CRC. Results: Eighteen prospective cohort studies with 931,469 participants, 14,860 CRC patients, 3536 colon cancer (CC) patients, and 1075 rectal cancer (RC) patients were included in the analysis. The summary RR of CRC for each 100-µg increase in dietary folate intake was 0.97 (95 % CI: 0.95-0.99, I2: 0.0 %, P-heterogeneity: 0.616), which can be related to BMI (0.97 (95 % CI: 0.95-0.99)); a more protective effect was also observed in subjects who drank alcohol (0.97 (95 % CI: 0.95-0.99)) and those who smoked (0.97 (95 % CI: 0.95-0.99)). Additionally, it was positively related to a 7 % lower risk of CC (0.93 (95 % CI: 0.87-0.99, I2: 33.7 %, P-heterogeneity: 0.159)), and the null relation for RC was 0.98 (95 % CI: 0.90-1.08), I2: 16.6 %, P-heterogeneity: 0.309). There was evidence of nonlinearity in which up to 500 µg/day dietary folate intake was inversely associated with CC (P nonlinearity = 0.04). Conclusion: The findings showed an inverse association between dietary folate intake and the risk of CRC, especially in high-risk persons, those who have a higher BMI, alcohol drinkers, and smokers.

Effect of Low-Fat Diet on Depression Score in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Clinical Trials.

CONTEXT: Current evidence on the effect of a low-fat (LF) diet on depression scores has been inconsistent. OBJECTIVE: To explore the effect of an LF diet on depression scores of adults by systematic review and meta-analysis of randomized controlled trials (RCTs). DATA SOURCES: The PubMed, ISI Web of Science, Scopus, and CENTRAL databases were searched from inception to June 7, 2023, to identify trials investigating the effect of an LF diet (fat intake ≤30% of energy intake) on the depression score. DATA EXTRACTION: Random-effects meta-analyses were used to estimate pooled summary effects of an LF diet on the depression score (as Hedges g). DATA ANALYSIS: Finding from 10 trials with 50 846 participants indicated no significant change in depression score following LF diets in comparison with usual diet (Hedges g = -0.11; 95% CI, -0.25 to 0.03; P = 0.12; I2 = 70.7% [for I2, 95% CI, 44%, 85%]). However, a significant improvement was observed in both usual diet and LF diets when the content of protein was 15-20% of calorie intake (LF, normal protein diet: n = 5, Hedges g = -0.21, 95% CI, -0.24 to -0.01, P = 0.04, I2 = 0%; usual, normal protein diet: n = 3, Hedges g = -0.28, 95% CI, -0.51 to -0.05, P = 0.01, I2 = 0%). Sensitivity analysis also found the depression score improved following LF diet intervention in participants without baseline depression. CONCLUSION: This study revealed that LF diet may have small beneficial effect on depression score in the studies enrolled mentally healthy participants. Moreover, achieving to adequate dietary protein is likely to be a better intervention than manipulating dietary fat to improve depression scores. However, it is not clear whether this effect will last in the long term. Conducting more studies may change the results due to the low-certainty of evidence. SYSTEMATIC REVIEW REGISTRATION: CRD42023420978 (https://www.crd.york.ac.uk/PROSPERO).

Effects of a low FODMAP diet on the symptom management of patients with irritable bowel syndrome: a systematic umbrella review with the meta-analysis of clinical trials.

A low FODMAP diet (LFD) is a common restrictive diet to manage the symptoms of irritable bowel syndrome (IBS). However, there is no consensus on the alleviating effects of this diet. Herein, a systematic umbrella review with meta-analysis was conducted to investigate the effect of an LFD on IBS symptoms and its secondary outcomes in patients, which were not reported in previous meta-analyses. We performed a systematic literature search in PubMed, Scopus, and ISI Web of Science up to December 2023. The methodological quality of systematic reviews and their included trials was evaluated using AMSTAR 2 and the Cochrane risk of bias, respectively. The certainty of the evidence tool was evaluated using the GRADE approach. The data related to IBS symptoms, quality of life (QoL), microbiome diversity, and stool short-chain fatty acids were extracted. A random-effect (if RCTs ≥ 6) or fixed-effect model (if RCTs < 5) was used to recalculate effect sizes and 95% CIs and report them in both qualitative and quantitative terms (pooled risk ratio, Hedges' g, and weighted mean difference). A total of 658 articles were initially identified, with 11 meta-analyses and 24 RCTs reporting 28 outcomes with 1646 participants included. An LFD significantly affected the clinical improvement of total symptoms according to the IBS-SSS questionnaire (RR: 1.42; 95% CI: 1.02, 1.97; P = 0.04) in all the subtypes of IBS and also had favorable effects on stool consistency (WMD: -0.48; 95% CI: -0.902, -0.07) and frequency (WMD: -0.36; 95% CI: -0.61, -0.10) and some other GI symptoms in both less and more than 4 weeks of diet intervention except for stool consistency, which needed more than 4 weeks of LFD implementation. A significant QoL improvement was observed but not in the anxiety and depression state. Furthermore, some studies showed that an LFD may increase fecal pH and dysbiosis and reduce SCFA and the abundance of Bifidobacterium. In conclusion, an LFD can alleviate symptoms and QoL in IBS patients, although dysbiosis may occur. Considering the low certainty of evidence, strong RCTs with more appropriate designs are needed.

Investigation about the correlation between the severity of metabolic-associated fatty liver disease and adherence to the Mediterranean diet.

BACKGROUND: Metabolic-associated fatty liver disease (MAFLD) is defined by fatty liver combined with a disturbed metabolic state. Mediterranean diet (MedDiet) contains anti-inflammatory, anti-oxidative, and anti-fibrotic components and is seemingly beneficial in the management of MAFLD. We aimed to evaluate the correlation between adherence to MedDiet and the severity of MAFLD. MATERIALS AND METHODS: Totally 101 adult patients diagnosed with MAFLD were enrolled in this cross-sectional study. Persian version of Mediterranean Diet Adherence Screener (MEDAS), demographics, clinical, laboratory, and FibroScan findings were collected. Correlation and regression analyses were performed. RESULTS: The mean of participants' age was 49.37 ± 12.14 (51.48 % male subjects). Six patients (5 diabetic and 1 pre-diabetic) had advanced fibrosis. Overall, 48.5 % had good adherence to MedDiet [the least MEDAS-1 (15.8 %) and the highest MEDAS-13 (99 %)]. The adherence score was significantly higher in married, female, non-smoker, and diabetic subjects, and patients with hypertension. Adherence to MedDiet had insignificant correlations with hepatic fibrosis (P = 0.888), steatosis (P = 0.208), waist-to-height ratio (P = 0.853), and FIB-4 score (P = 0.919). Vitamin D level had just significant inverse associations with steatosis score (r = -0.21, P = 0.037) and no significant association was found with fibrosis score (r = -0.036, P = 0.717) and MedDiet adherence (r = 0.055, P = 0.581). According to the multiple regression analyses, less fruit intake, lower platelet count and DM had significant positive correlations with MAFLD severity (P < 0.001). CONCLUSION: Adherence to Mediterranean diet, particularly a higher fruit intake, is associated with a lower severity of MAFLD. Dietary modification based on taste, economic state, and culture should be deliberated in different geographic areas along with nutritional education.

L-Arginine is a feasible supplement to heal chronic anal fissure via reducing internal anal sphincter pressure: a randomized clinical trial study.

The hypertonicity of internal anal sphincter resting pressure is one of the main causes of chronic anal fissure. Therefore, the aim of this study was to assess the effect of oral administration of L-arginine on the improvement of the anal fissures by relaxing the internal anal sphincter. Seventy-six chronic anal fissure patients (aged 18-65 years) who were referred to Rasoul-e-Akram Hospital, Tehran, Iran from February 2019 to October 2020 participated in this randomized, double-blind, placebo-controlled trial. Participants were allocated into treatment (L-arginine) and placebo groups. They took a 1000 mg capsule three times a day for 1 month, and then we followed them at the end of the first and third months after the intervention. Clinical symptoms, anal sphincter resting pressure, and quality of life (QoL) were completed at baseline and the end of the study. The analysis of data showed a significant decrease in bleeding, fissure size, and pain for each group; however, in the L-arginine group was more than the control group at the end of the study (P values < 0.001). Following that, a significant increase in QoL was seen just in patients treated with L-arginine (P value = 0.006). In addition, the comparison of anal pressures at baseline and, between groups at the end of the study showed a significant reduction in sphincter pressure in patients treated with L-arginine (P value < 0.001, = 0.049; respectively). The oral administration of 3000 mg L-arginine can heal chronic anal fissures by reducing internal anal sphincter pressure with more negligible side effects. However, we recommend long-term study with more extended follow-up.Clinical trial registry: IRCT20190712044182N1 at Iranian clinical trials, date: 2019-08-27.

Association between dietary antioxidant index and risk of Helicobacter pylori infection among adults: a case-control study.

BACKGROUNDS AND AIMS: One of the most important risk factors for Helicobacter pylori (H. pylori) infection is nutrition. Balanced diets with high antioxidant properties may have protective effects against the consequences of this infection. In the current study, we aimed to investigate the association between the dietary antioxidant index and the risk of H. pylori infection among adults. METHODS: In a case-control study the dietary intake of patients with H. pylori infection was compared with healthy subjects. The dietary antioxidant index (DAI) was calculated using dietary intakes derived from a validated food frequency questionnaire (FFQ). Demographic information was obtained by a related questionnaire and Physical Activity was measured by International Physical Activity Questionnaire (IPAQ) were used to obtain information. Using logistic regression models, we evaluated the association between the DAI and H. pylori infection risk. The significance level was determined as P < 0.05. RESULTS: Finally, dietary data of 148 cases and 302 controls (mean age: 38.72 ± 10.61 (were analyzed. The mean of total DAI was significantly higher in controls (7.67) when compared with H. pylori cases (3.57) (P < 0.001). After adjustment for covariates, participants with less than median DAI values had an increased risk of H. pylori onset (adjusted OR 1.08, 95% CI: 1.02-1.12, P < 0.001). CONCLUSIONS: Appropriate intake of nutrient antioxidants may have a role in decreasing the likelihood of H. pylori infection risk.

A positive effect of egg consumption on macular pigment and healthy vision: a systematic review and meta-analysis of clinical trials.

Increasing macular pigment optical density (MPOD) as a result of increased macular concentration of lutein and zeaxanthin may reduce the risk of age-related macular degeneration (AMD). The aim of the present study was to determine whether the consumption of eggs, a rich source of dietary lutein and zeaxanthin, influences MPOD and serum lutein. In this systematic review and meta-analysis we searched PubMed, Scopus, and ISI Web of Science up to July 2020, for relevant randomized clinical trials. Using a random-effects model, pooled weighted mean differences, and standard deviations (SDs) for each outcome were obtained. The quality of the eligible studies was assessed by the Cochrane Collaboration's tool. A meta-analysis of five trials (296 participants) revealed that egg consumption significantly increased MPOD (weighted mean differences (WMD): +0.037; 95% CI: 0.004, 0.069; P = 0.027) and serum lutein (WMD: +0.150 µmol L̂-1; 95% CI: 0.037, 0.263; P = 0.009). Subgroup analyses showed that egg consumption: (a) had a larger effect on MPOD in studies with a parallel design; and (b) increased serum lutein to a greater extent in a healthy population. We did not detect any heterogeneity between studies. Daily egg consumption has beneficial effects on MPOD and serum lutein is inversely associated with reduced AMD progression. Further clinical trials are required to confirm the results of this study. © 2021 Society of Chemical Industry.

Effects of vitamin D3 supplementation on clinical symptoms, quality of life, serum serotonin (5-hydroxytryptamine), 5-hydroxy-indole acetic acid, and ratio of 5-HIAA/5-HT in patients with diarrhea-predominant irritable bowel syndrome: A randomized clinical trial.

Vitamin D deficiency, common in the population with irritable bowel syndrome (IBS), can induce the main factors that lead to IBS clinical symptoms, such as depression, anxiety, and inflammation. Serotonin (5-HT) plays an important role in the pathophysiology of IBS, and its production and secretion are increased from the lumen due to stress and inflammation. The aim of this study was to evaluate the effect of vitamin D3 supplementation on the pathogenesis of diarrhea-predominant IBS (IBS-D). Seventy-four IBS-D patients (age: 18-65 y) participated in a randomized, double-blind, placebo-controlled trial study from February 2017 to May 2018, at Rasoul-e-Akram Hospital, Tehran, Iran. Subjects were allocated into two groups receiving 50,000 IU/week of vitamin D3 or placebo for 9 weeks. IBS severity score system (IBS-SSS), IBS-quality of life questionnaire (QoL), hospital anxiety and depression Scale (HADs), visceral sensitivity index (VSI) and serum 25(OH) vitamin D3, serotonin, 5-hydroxy-indole acetic acid and ratio of 5-HIAA/5-HT were evaluated before and after the interventions. Symptoms severity, QoL, HADs-depression, and VSI score improved significantly in the vitamin D group as compared to the placebo group (P-values: <0.001, 0.049, 0.023, and 0.008; respectively). There were no significant differences in abdominal bloating, HADs-anxiety, serum 5-HT, 5-HIAA, and 5-HIAA/5-HT between the two groups at the end of the study. Based on our results, we recommend serum vitamin D be evaluated in the process of treatment of these patients to ameliorate symptoms and quality life of IBS-D patients with vitamin D deficiency and/or insufficiency.

The responses of different dosages of egg consumption on blood lipid profile: An updated systematic review and meta-analysis of randomized clinical trials.

Diverse notions exist regarding egg intake, which is one of the main sources of dietary cholesterol, and its effect on blood lipids. We conducted this study to update the previous meta-analysis for their flaw in calculated effect size. PubMed, Scopus, ISI, and Cochrane were searched up to April 2019, for relevant randomized controlled clinical trials. Mean changes in total cholesterol (TC), LDL-cholesterol (LDL-C), HDL-cholesterol (HDL-C), triglyceride (TG), very low-density lipoprotein cholesterol (VLDL-C), LDL-C/HDL-C, TC/HDL-C, apolipoprotein (apo)A1, and apoB100 were assessed. Meta-analysis of 66 RCTs with 3,185 participants revealed that egg consumption can significantly increase TC, LDL-C, HDL-C, TC/HDL-C, apoA1/and B100, but there was no significant effect on other serum lipids. Dose-response analysis showed a linear effect for TC, HDL-C, ApoA1, ApoB100, and nonlinear for LDL-C, and TC/HDL-C. In conclusion, intake of more than one egg daily in less than 12 weeks may increase some blood lipids without any changes in the ratio of LDL-C/HDL-C. PRACTICAL APPLICATIONS: There are controversies reports for egg intake, which is one of the main sources of dietary cholesterol. This study provides comprehensive information about the effect of the number of eggs consumed per day (dietary cholesterol) on blood lipids for nutritionists, physicians, researchers, and the general population. In this regard, our results indicated that there is a linear correlation between consumption of greater than one egg per day in a short time (no long time) and increasing lipid profiles which may increase the risk of cardiovascular diseases. However, consumption of one egg daily can be safe and this can be a useful recommendation for prevention of cardiovascular disease and promotion of healthy life which indeed are the potential or actual uses of this research.

Vitamin D3 Supplementation in Diarrhea-Predominant Irritable Bowel Syndrome Patients: The Effects on Symptoms Improvement, Serum Corticotropin-Releasing Hormone, and Interleukin-6 - A Randomized Clinical Trial.

OBJECTIVES: This study aimed to evaluate whether vitamin D deficiency is associated with the severity of symptoms of irritable bowel syndrome (IBS) patients. Stress and gut inflammation can increase the serum level of corticotropin-releasing hormone (CRH) and interleukin-6 (IL-6), leading to a change in bowel movements. The aim of this study was to evaluate the anti-inflammatory and psychological effects of vitamin D3 supplementation on the symptom improvement of patients with a diarrhea-predominant form of IBS (IBS-D). METHODS: Eighty-eight IBS-D patients (age: 18-65 years) based on Rome IV criteria who suffered from vitamin D deficiency and/or insufficiency were enrolled in this randomized, placebo-controlled trial from February 2017 to May 2018 at Rasoul-e-Akram Hospital, Tehran, Iran. Participants were randomly divided into two groups. The intervention group received 50,000 IU vitamin D3 weekly and the control group received a placebo for 9 weeks. All patients received Mebeverine 135 mg twice a day besides supplementation. The IBS Severity Score System (IBS-SSS), serum 25(OH) vitamin D3, CRH, and IL-6 were measured before and after interventions. RESULTS: Seventy-four patients completed the study. The severity of IBS symptoms (p < 0.01) and IL-6 (p = 0.02) decreased significantly in the intervention group as compared to the control group, but there was no significant difference in the serum level of CRH. Also, in the treatment group, IBS-SSS and IL-6 were significantly reduced at the end of the study from baseline (p < 0.01 and p < 0.03, respectively). CONCLUSION: Our findings indicate that vitamin D3 supplementation can modulate the serum level of CRH and IL-6 and can improve symptoms in IBS-D patients. Vitamin D3 supplementation should be considered in IBS-D patients who suffer from vitamin D deficiency and/or insufficiency.