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Background and Aims: Vitamin D deficiency impacts a significant proportion of the world's population, and this deficiency has been linked to various conditions characterized by imbalanced serotonin regulation. The objective of this systematic review and meta‐analysis was to evaluate the effect of vitamin D supplementation on serum serotonin levels. Methods: We conducted a comprehensive search of PubMed, Scopus, Cochrane Central for Randomized Clinical Trials, and Web of Science up to September 2022, without any language restrictions. The effect sizes were calculated using the standard mean difference (SMD) and 95% confidence interval (CI). Results: Six randomized clinical trials involving 356 participants were included in the analysis. Our findings indicated no significant changes in serotonin levels between the intervention and control groups (SMD: 0.24 ng/mL, 95% CI: −0.28, 0.75, p > 0.10). Subgroup analysis also did not reveal any significant changes in serotonin levels among children, participants with autism spectrum disorders, interventions lasting 10 weeks or longer, or those receiving vitamin D doses below 4000 IU/day. Conclusion: Although the results obtained in this systematic review are inconclusive, they support the need for further well‐designed randomized trials to assess the potential role of vitamin D supplementation in regulating serotonin levels and potentially ameliorating depression and related disorders. [ABSTRACT FROM AUTHOR]

Cardiovascular diseases (CVDs) have become the leading global cause of mortality, prompting a heightened focus on identifying precise indicators for their assessment and treatment. In this perspective, the plasma levels of HDL have emerged as a pivotal focus, given the demonstrable correlation between plasma levels and cardiovascular events, rendering them a noteworthy biomarker. However, it is crucial to acknowledge that HDLs, while intricate, are not presently a direct therapeutic target, necessitating a more nuanced understanding of their dynamic remodeling throughout their life cycle. HDLs exhibit several anti-atherosclerotic properties that define their functionality. This functionality of HDLs, which is independent of their concentration, may be impaired in certain risk factors for CVD. Moreover, because HDLs are dynamic parameters, in which HDL particles present different atheroprotective properties, it remains difficult to interpret the association between HDL level and CVD risk. Besides the antioxidant and anti-inflammatory activities of HDLs, their capacity to mediate cholesterol efflux, a key metric of HDL functionality, represents the main anti-atherosclerotic property of HDL. In this review, we will discuss the HDL components and HDL structure that may affect their functionality and we will review the mechanism by which HDL mediates cholesterol efflux. We will give a brief examination of the effects of aging and diet on HDL structure and function. [ABSTRACT FROM AUTHOR]

Background: There are randomized controlled trials (RCTs) about the zinc supplementation effect on circulating levels of brain-derived neurotrophic factor (BDNF). However, the findings of these studies are inconsistent. The purpose of this systematic review and meta-analysis was to determine the zinc supplementation effect on BDNF and zinc levels in published RCTs. Methods: We searched PubMed/Medline, Cochrane, Scopus, ISI Web of Science, EMBASE, "Clinicaltrials.gov", "Cochrane Register of Controlled Trials", "IRCT" and also key journals up to 2019. RCTs with two intervention (zinc) and control (placebo) groups that evaluated zinc supplementation efficacy on BDNF levels were included. Study heterogeneity was assessed, and then, meta-analysis was performed using the fixed-effects model. Results: Four studies were included in the present secondary analysis. Compared with placebo, zinc supplementation significantly enhanced circulating levels of BDNF [(SMD): 0.31, 95% confidence interval (CI): (0.22, 0.61)] and zinc [(SMD): 0.88, 95% CI: (0.54, 1.22)] with no considerable heterogeneity among the studies [(Q = 3.46; P = 0.32; I2% = 13.4); (Q = 2.01; P = 0, 37; I2% = 0.5), respectively]. Conclusions: Our results propose that zinc supplementation can increase the circulating levels of BDNF and zinc. This study was registered at PROSPERO as CRD42020149513. [ABSTRACT FROM AUTHOR]

Despite the apparent beneficial effects of probiotics/synbiotics on glucose haemostasis, lipid profile and inflammatory responses, it is not clear whether these beneficial effects also impact renal and hepatic function in diabetes. Therefore, we sought to assess the effect of probiotics/synbiotics supplementation on renal and liver biomarkers in adults with type 2 diabetes mellitus (T2DM) using a systematic review and meta-analysis of randomised controlled trials (RCT). PubMed, Scopus, Web of Science and Cochrane Library were systematically searched, up to February 2021. The pooled weighted mean difference (WMD) was estimated using a random-effects model. The methodological quality of studies, as well as certainty of evidence, was assessed using standard scales. Fifteen related trials were identified. Meta-analysis of six trials, involving 426 participants, indicated that probiotics/synbiotics supplementation reduced serum levels of creatinine (WMD = −0·10 mg/dl, 95 % CI −0·20, −0·00; P = 0·01; I2 = 87·7 %; P-heterogeneity < 0·001), without any significant effect on blood urea nitrogen (BUN), glomerular filtration rate or microalbuminuria. No significant improvement was found on liver biomarkers following probiotics/synbiotics supplementation. The subgroup analysis showed a significant improvement in BUN when follow-up duration lasted for 12 weeks or more (WMD = −1·215 mg/dl, 95 % CI −1·933, −0·496; P = 0·001) and in creatinine levels in patients with renal dysfunction (WMD = −0·209 mg/dl, 95 % CI −0·322, −0·096; P < 0·001). Our results are insufficient to advocate the use of probiotics/synbiotics for improving renal or liver function in patients with T2DM. Indeed, due to the low certainty of evidence, these findings need to be affirmed in further high-quality RCT. [ABSTRACT FROM AUTHOR]