The association of dietary nitrates/nitrites intake and the gut microbial metabolite trimethylamine N-oxide and kynurenine in adults: a population-based study.

Background: Dietary nitrate and nitrite may affect the gut microbiota and its metabolites, such as trimethylamine N-oxide (TMAO) and kynurenine (KYN). However, this association and the exact mechanism are still unclear. Therefore, this study aimed to assess the association between dietary consumption of nitrite and nitrate on TMAO and KYN levels in adults. Methods: This cross-sectional study was employed on a subsample baseline phase of the Tehran University of Medical Sciences (TUMS) Employee's Cohort Study (TEC). A total of 250 adults aged 18 years or older were included in the current analysis. Data on the dietary intakes were collected using a validated dish-based food frequency questionnaire (FFQ), and dietary intakes of nitrite and nitrate were estimated using the FFQ with 144 items. Serum profiles and TMAO and KYN were measured using a standard protocol. Results: The findings of this study demonstrate a significant association between the intake of animal sources of nitrate and nitrite and the likelihood of having elevated levels of TMAO and KYN. Specifically, after adjustment, individuals with the highest intake adherence to nitrates from animal sources exhibited increased odds of having the highest level of TMAO (≥51.02 pg/ml) (OR = 1.51, 95% CI = 0.59-3.88, P = 0.03) and KYN (≥417.41 pg/ml) (OR = 1.75, 95% CI = 0.73-4.17, P = 0.02). Additionally, subjects with the highest animal intake from nitrite sources have 1.73 and 1.45 times higher odds of having the highest levels of TMAO and KYN. These results emphasize the potential implications of animal-derived nitrate and nitrite consumption on the levels of TMAO and KYN. Conclusion: The present evidence indicates that a high level of nitrate and nitrite intake from animal sources can increase the odds of high levels of TMAO and KYN. Further studies suggest that we should better evaluate and understand this association.

Serum levels of trimethylamine N-oxide and kynurenine novel biomarkers are associated with adult metabolic syndrome and its components: a case-control study from the TEC cohort.

Background: Epidemiologic research suggests that gut microbiota alteration (dysbiosis) may play a role in the pathogenesis of metabolic syndrome (MetS). Dysbiosis can influence Trimethylamine N-oxide (TMAO) a gut microbiota-derived metabolite, as well as kynurenine pathways (KP), which are known as a new marker for an early predictor of chronic diseases. Hence, the current study aimed to investigate the association between KYN and TMAO with MetS and its components. Methods: This case-control study was conducted on 250 adults aged 18 years or over of Tehran University of Medical Sciences (TUMS) Employee's Cohort study (TEC) in the baseline phase. Data on the dietary intakes were collected using a validated dish-based food frequency questionnaire (FFQ) and dietary intakes of nitrite and nitrate were estimated using FFQ with 144 items. MetS was defined according to the NCEP ATP criteria. Serum profiles TMAO and KYN were measured by standard protocol. Result: The mean level of TMAO and KYN in subjects with MetS was 51.49 pg/mL and 417.56 nmol/l. High levels of TMAO (≥30.39 pg/mL) with MetS were directly correlated, after adjusting for confounding factors, the odds of MetS in individuals 2.37 times increased (OR: 2.37, 95% CI: 1.31-4.28, P-value = 0.004), also, high levels of KYN (≥297.18 nmol/L) increased odds of Mets+ 1.48 times, which is statistically significant (OR: 1.48, 95% CI: 0.83-2.63, P-value = 0.04). High levels of TMAO compared with the reference group increased the odds of hypertriglyceridemia and low HDL in crude and adjusted models (P < 0.05). Additionally, there was a statistically significant high level of KYN increased odds of abdominal obesity (P < 0.05). Conclusion: Our study revealed a positive association between serum TMAO and KYN levels and MetS and some of its components. For underlying mechanisms and possible clinical implications of the differences. Prospective studies in healthy individuals are necessary.

The association between adherence to alternative healthy Diet Index (AHEI) and severity, disability, duration, and frequency of migraine headache among women: a cross-sectional study.

BACKGROUND: Migraine is a common brain disorder characterized by recurrent seizures lasting between 4 and 72 h. Dietary factors can affect migraine headaches. The Alternative Healthy Diet Index (AHEI) is a measure of diet quality and adherence to healthy dietary patterns. This study aimed to assess the association of adherence to AHEI and severity, disability, duration, and frequency of migraine headaches. METHODS: In this cross-sectional study, 266 women who suffered from migraines were selected. Usual dietary intakes were assessed using a semi-quantitative, 147-item, food frequency questionnaire (FFQ). AHEI was calculated based on FFQ. The Migraine Disability Assessments (MIDAS) and Visual Analog Scale (VAS) questionnaires were used to evaluate migraine disability, severity and the pain, duration and frequency of headaches. RESULTS: People with high adherence to AHEI, compared with low adherence, had a 43% reduction in headache duration in the crude model (OR = 0.57; 95% CI 0.34, 0.97; P = 0.03), which remained significant after adjusting for potential confounders (OR = 0.56; 95% CI 0.31, 0.99; P = 0.04). No association was found between the frequency of migraine and AHEI in both crude and adjusted models (OR = 1.19; 95% CI 0.66, 2.14; P = 0.55). In addition, no significant association was found between high adherence of AHEI and odds of severe and moderate headaches (P > 0.05). CONCLUSION: The results of our study showed that people with high adherence of AHEI had a 43% reduction in duration of migraine. More studies are needed to evaluate and better understand this relationship.

The effects of Gymnema Sylvestre supplementation on lipid profile, glycemic control, blood pressure, and anthropometric indices in adults: A systematic review and meta-analysis.

There is a growing interest in the considerable health benefits of Gymnema Sylvestre (GS) supplementation, as some studies have reported that it may improve cardiometabolic risk factors. However, the widespread impact of GS supplementation on the parameters mentioned above is not fully resolved. Consequently, this study aimed to examine the effects of GS supplementation on lipid profile, glycemic control, blood pressure, and anthropometric indices in adults. Eligible randomized controlled trials (RCT), published up to November 2021, were identified through PubMed, Scopus, and ISI Web of Science databases. Six studies were included and analyzed using a random-effects model to calculate weighted mean differences (WMDs) with 95% confidence intervals (CI). All studies were conducted in adults that used a GC supplement (>1 week) and assessed our selected cardiovascular risk factors. Outcomes revealed that GS supplementation significantly decreased triglyceride (p < .001), total cholesterol (p < .001), low-density lipoprotein (p < .001), fasting blood sugar (p < .001), and diastolic blood pressure (p = .003). Some limitations, including notable heterogeneity, low quality of studies, and lack of diversity among research participants, should be considered when interpreting our results. Our outcomes suggest that GS supplementation may improve cardiovascular risk factors. Future large-high-quality RCTs with longer duration and various populations are needed to firmly establish the clinical efficacy of the plant.

The Effect of Saffron Supplementation on Blood Pressure in Adults: A Systematic Review and Dose-Response Meta-Analysis of Randomized Controlled Trials.

BACKGROUND: The favorable influences of saffron supplementation on metabolic diseases have previously been shown. We aimed to assess the effects of saffron supplementation on blood pressure in adults. METHODS: A systematic search was performed in Scopus, Embase, and the Cochrane library databases to find randomized controlled trials (RCTs) related to the effect of saffron supplementation on blood pressure in adults up to March 2021. The primary search yielded 182 publications, of which eight RCTs were eligible. RESULTS: Our results showed that saffron supplementation resulted in a significant decrease in systolic blood pressure (weighted mean difference (WMD): -0.65 mmHg; 95% CI: -1.12 to -0.18, p = 0.006) and diastolic blood pressure (DBP) (WMD: -1.23 mmHg; 95% CI: -1.64 to -0.81, p < 0.001). Moreover, saffron supplementation reduced DBP in a non-linear fashion, based on duration (r = -2.45, p-nonlinearity = 0.008). CONCLUSIONS: Saffron supplementation may significantly improve both systolic and diastolic blood pressure in adults. It should be noted that the hypotensive effects of saffron supplementation were small and may not reach clinical importance.

The Effects of Nano-Curcumin Supplementation on Risk Factors for Cardiovascular Disease: A GRADE-Assessed Systematic Review and Meta-Analysis of Clinical Trials.

BACKGROUND: Previous studies have indicated that curcumin supplementation may be beneficial for cardiometabolic health; however, current evidence regarding the effects of its nanorange formulations, popularly known as "nano-curcumin", remains unclear. This systematic review and meta-analysis aimed to determine the impact of nano-curcumin supplementation on risk factors for cardiovascular disease. METHODS: PubMed, Scopus, Embase, and ISI web of science were systematically searched up to May 2021 using relevant keywords. All randomized controlled trials (RCTs) investigating the effects of nano-curcumin supplementation on cardiovascular disease risk factors were included. Meta-analysis was performed using random-effects models, and subgroup analysis was performed to explore variations by dose and baseline risk profiles. RESULTS: According to the results of this study, nano-curcumin supplementation was associated with improvements in the glycemic profile by decreasing fasting blood glucose (FBG) (WMD: -18.14 mg/dL; 95% CI: -29.31 to -6.97; p = 0.001), insulin (WMD: -1.21 mg/dL; 95% CI: -1.43 to -1.00; p < 0.001), and HOMA-IR (WMD: -0.28 mg/dL; 95% CI: -0.33 to -0.23; p < 0.001). Interestingly, nano-curcumin supplementation resulted in increases in high-density lipoprotein (HDL) (WMD: 5.77 mg/dL; 95% CI: 2.90 to 8.64; p < 0.001). In terms of other lipid profile markers (triglyceride (TG), total cholesterol (TC), and low-density lipoprotein (LDL)), subgroup analyses showed that nano-curcumin supplementation had more favorable effects on lipid profiles in individuals with dyslipidemia at baseline. Nano-curcumin supplementation also showed favorable anti-inflammatory effects by decreasing C-reactive protein (CRP) (WMD: -1.29 mg/L; 95% CI: -2.15 to -0.44; p = 0.003) and interleukin-6 (IL-6) (WMD: -2.78 mg/dL; 95% CI: -3.76 to -1.79; p< 0.001). Moreover, our results showed the hypotensive effect of nano-curcumin, evidenced by a decrease in systolic blood pressure (SBP). CONCLUSIONS: In conclusion, our meta-analysis suggests that nano-curcumin supplementation may decline cardiovascular disease risk by improving glycemic and lipid profiles, inflammation, and SBP. Future large-scale investigations with longer durations are needed to expand on our findings.