Flavonoid intake and eye health

The association between food diversity and serum antioxidant indices in cataract patients compared to healthy subjects

BACKGROUND

Cataract is a chronic disorder that is related to antioxidant-oxidant imbalance situation. We aimed to investigate the association between food diversity and serum antioxidant and oxidant indices in cataract patients compared to healthy subjects.

MATERIALS AND METHODS

In this case-control study, ninety volunteers (aged > 50 years) were divided into the cataract (n = 45) and healthy control (n = 45) groups. Anthropometric variables, physical activity and stress levels, food diversity score, serum total oxidant capacity (TOC), and total antioxidant capacity (TAC) measurements were done for all participants.

RESULTS

Serum TAC, even after adjustment for stress level, was significantly higher in healthy people compared to cataract patients (P < 0.001). In addition, serum TOC was significantly lower in healthy controls compared to cataract patients (P < 0.002). In healthy group, there was a weak significant positive association between serum TAC and meats group diversity (r = 0.149, P = 0.047). In addition, there was a moderate negative association between meats group diversity and TOC in the healthy controls (r = -0.712, P = 0.041). In the cataract group, there was a significant negative association between serum TOC and diversity score of fruits (r = -0.811, P = 0.017) and meats group (r = -0.926, P = 0.046) as well as total score of food diversity (r = -0.466, P = 0.003).

CONCLUSION

It seems that increase in total dietary diversity and food groups' diversity can have a beneficial effect on oxidant situation among cataract patients.

Effects of Flavonoid Supplementation on Common Eye Disorders: A Systematic Review and Meta-Analysis of Clinical Trials

Background: Emerging studies show that certain plant compounds may reduce the severity of most prevalent ocular abnormalities. The aim of this systematic review and meta-analysis was to assess the effect of dietary flavonoids on major eye disorders.

Methods: Eligible studies were identified by searching PubMed, Web of Science, Scopus, and Cochrane Library databases for all articles published up to April 2021. The literature search yielded 1,134 articles, and a total of 16 studies were included in the systematic review. A meta-analysis of 11 intervention trials involving a total of 724 participants was performed.

Results: Using a random-effects model, the pooled results revealed an overall significant effect of flavonoids on common ophthalmic disorders (standard mean difference = −0.39; 95% CI: −0.56, −0.21, p < 0.01). Of the subclasses of flavonoids, flavan-3-ols (standard mean difference = −0.62; 95% CI: −1.03, −0.22, p < 0.01), and anthocyanins (standard mean difference = −0.42; 95% CI: −0.63, −0.21, p < 0.01) were the only effective intervention for improving the outcomes of ocular conditions. For several of the other flavonoid subclasses, evidence on efficacy was insufficient.

Conclusion: Our findings indicate that flavonoids may improve the clinical manifestations associated with ocular disorders. However, further well-constructed clinical trials are required to confirm these results and examine the effect of flavonoids on eye disorders other than those identified in this review.

Systematic Review Registration: PROSPERO, identifier CRD42021247332.

Herbal nutraceutical treatment of chronic prostatitis-chronic pelvic pain syndrome: a literature review

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is the most frequent form of prostatitis, and has a serious impact on patients' quality of life, and causes severe symptoms. The pain in the pelvic, perineal and penile areas, lower abdominal pain, and pain during urination or ejaculation are the main complaints of CP/CPPS. The underlying complex and unknown pathophysiology of this syndrome have made the management of CP/CPPS and the availability of monotherapy challenging. To identify an effective monotherapy, a plethora of clinical trials failed due to its puzzling etiology. Antibiotics, anti-inflammatory, and a-blockers have been commonly used for the treatment of CP/CPPS, but the desired and complete effects have not been gotten yet. The patients and clinicians are attracted to alternative therapies because of their multi-targeted effects. Attention toward natural compounds effectiveness and safety, supporting the development of a new nutraceutical science. In the alternative remedies for the treatment of prostatic diseases, medicinal herbs, in the form of herb parts or extracts, are getting attention due to their positive effects on prostatic diseases. At present, there is no available detailed literature review about the efficacy of medicinal herbs in the treatment of CP/CPPS. This review aimed to explore the useful medicinal herbs in the treatment of CP/CPPS from different perspectives and their possible mechanism of action in managing CP/CPPS.

Inflammation in Glaucoma: From the back to the front of the eye, and beyond

The pathophysiology of glaucoma is complex, multifactorial and not completely understood. Elevated intraocular pressure (IOP) and/or impaired retinal blood flow may cause initial optic nerve damage. In addition, age-related oxidative stress in the retina concurrently with chronic mechanical and vascular stress is crucial for the initiation of retinal neurodegeneration. Oxidative stress is closely related to cell senescence, mitochondrial dysfunction, excitotoxicity, and neuroinflammation, which are involved in glaucoma progression. Accumulating evidence from animal glaucoma models and from human ocular samples suggests a dysfunction of the para-inflammation in the retinal ganglion cell layer and the optic nerve head. Moreover, quite similar mechanisms in the anterior chamber could explain the trabecular meshwork dysfunction and the elevated IOP in primary open-angle glaucoma. On the other hand, ocular surface disease due to topical interventions is the most prominent and visible consequence of inflammation in glaucoma, with a negative impact on filtering surgery failure, topical treatment efficacy, and possibly on inflammation in the anterior segment. Consequently, glaucoma appears as an outstanding eye disease where inflammatory changes may be present to various extents and consequences along the eye structure, from the ocular surface to the posterior segment, and the visual pathway. Here we reviewed the inflammatory processes in all ocular structures in glaucoma from the back to the front of the eye and beyond. Our approach was to explain how para-inflammation is necessary to maintain homoeostasis, and to describe abnormal inflammatory findings observed in glaucomatous patients or in animal glaucoma models, supporting the hypothesis of a dysregulation of the inflammatory balance toward a pro-inflammatory phenotype. Possible anti-inflammatory therapeutic approaches in glaucoma are also discussed.

Benefits of micronutrient supplementation for reducing the risk of wet age-related macular disease and diabetic retinopathy

Age-related macular disease and diabetic retinopathy are chronic degenerative diseases characterised by progressive visual impairment. In Europe, age-related macular disease accounts for over 15% of blindness in adults over 50 years of age, and although the burden of diabetic retinopathy in terms of vision impairment is lower, vision loss associated with diabetic retinopathy is increasing with the rising prevalence of diabetes mellitus and the ageing of the population. Late-stage age-related macular disease can be subdivided into dry (non-neovascular) or wet (neovascular or exudative) forms. The large Age-Related Eye Disease Study 2 showed that supplementation with antioxidant nutrients reduces choroids neovascularisation and reduces the risk of progression of neovascular age-related macular disease. Antioxidant micronutrient supplements have also shown promising results in preventing the pathogenesis of retinopathy in animal models of diabetes. Age-related macular disease and diabetic retinopathy are understood to share some common pathophysiological characteristics, suggesting that micronutrients have an important role in ocular health in both conditions. This article will review the current evidence for the utility of micronutrients in preventing the development and progression of neovascular age-related macular disease and diabetic retinopathy.

The Effect of Flavonoids on Chronic Prostatitis: A Meta-analysis of Published Randomized Controlled Trials

OBJECTIVE

To assess the effect of flavonoids on chronic prostatitis, a meta-analysis of randomized controlled trials was performed.

METHODS

Through using subject word and random word, PubMed, Scopus, Web of Science, and Cochrane Library were searched for related records up to July 2018. The response rate and National Institutes of Health-Chronic Prostatitis Symptom Index (NIH-CPSI) were used to evaluate the therapeutic efficacy of the flavonoids. The Cochrane handbook for systematic reviews of interventions version was used to evaluate the quality of included studies. The model of determining odds ratio (OR) was chose according to the value of I².

RESULTS

A total of 11 studies involving 975 subjects (experiment 516, control 459) were included. The overall OR of response rate was 0.31 (95%CI 0.11-0.89, P = 0.03). At the subgroup analysis, the OR of response rate of chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) was 0.57 (95%CI 0.18-1.77, P = 0.33), while the OR of response rate of chronic bacterial prostatitis (CBP) was 0.08 (95%CI 0.02-0.33, P = 0.0005). The OR of response rate of CP/CPPS (control was placebo) was 0.29 (95%CI 0.16-0.52, P < 0.0001). The overall OR of baseline NIH-CPSI was -0.1 (95%CI -0.61-0.41, P = 0.70). The overall OR of posttreatment NIH-CPSI was -6.96 (95%CI -8.32∼ -5.60, P < 0.00001).

CONCLUSIONS

This meta-analysis indicates that the flavonoids may be clinically beneficial through significantly improving the response rate and NIH-CPSI in chronic prostatitis patients and short-lasting antibiotics therapy in association with the flavonoids could be a better choose for CBP. Moreover, the flavonoids therapy has an excellent safety profile with minor adverse effects.

Effect of Myricetin on Primary Open-angle Glaucoma

Background

Primary open angle glaucoma (POAG) is the most common form of glaucoma, with a multifactorial etiology that results in retinal ganglion cell death and loss of vision. In this study, we assessed the effects of myricetin on the trabecular meshwork cells in POAG.

Methods

In the in-vivo model, glaucoma was induced in Sprague-Dawley rats by injecting hyaluronic acid into the anterior chamber of the eye (every week for six-weeks). Treatment group rats were administered myricetin (25, 50 or 100 mg/ kg body weight via oral gavage) each day for of six weeks.

Results

POAG TM cells exposed to myricetin (25, 50 or 100 μM) exhibited significantly lowered reactive oxidative species (ROS) levels and lipid peroxidation products. The expressions of transforming growth factors (TGFβ1/β2), vascular endothelial growth factor, and senescence markers (senescence associated-β-galactosidase, cyclin-dependent kinase inhibitors-p16 and p21) were substantially down-regulated in POAG TM cells exposed to myricetin. Myricetin effectively prevented IOP elevation in glaucoma-induced rats and decreased inflammatory cytokines (IL-1α, IL-1β, IL-6, Il-8, TNF-α) in the aqueous humor and POAG TM cells of glaucoma-induced rats.

Conclusion

The observations of the study illustrate the protective effects of myricetin in glaucomatous TM cells.

Prospective study of flavonoid intake and risk of primary open-angle glaucoma

PURPOSE

To evaluate the association between flavonoid intake and incident primary open-angle glaucoma (POAG).

METHODS

We followed 65 516 women from the Nurses' Health Study (from 1984) and 42 156 men from the Health Professionals Follow-up Study (from 1986) biennially to 2012, who were 40+ years old, free of POAG, and reported eye examinations. Dietary flavonoid intake was assessed with validated repeated semi-quantitative food frequency questionnaires. Incident POAG cases (n = 1575) were confirmed with medical record review. Cohort-specific multivariable-adjusted relative risks (RRs) and 95% confidence intervals (CIs) were calculated and meta-analysed.

RESULTS

Total flavonoid intake was not associated with risk of POAG development [RR for highest (Q5: median ~645 mg/day) versus lowest quintile (Q1: ~130 mg/day) = 0.91 (95% CI = 0.77, 1.08); p for trend (p-trend) = 0.19]; the flavonoid subclasses of flavones, flavanones, polymeric flavanols or anthocyanidins were also not associated (Q5 versus Q1 comparison p-values ≥0.05 and p-trend ≥0.09). Higher intakes of flavonols and monomeric flavanols were nominally associated with lower POAG risk, based on the Q5 versus Q1 comparisons or p-trends. The Q5 versus Q1 comparison RRs were: for flavonols, 0.82 (95% CI = 0.69, 0.97; p-trend = 0.05; ~28 versus ~8 mg/day), and for monomeric flavanols, 0.86 (95% CI = 0.72, 1.02; p-trend=0.04; ~110 versus 10 mg/day). The food/beverage that contributed most to both the variation of flavonols and monomeric flavanols was tea; consuming ~2 cups/day was associated with 18% lower POAG risk (RR=0.82; 95% CI = 0.68, 0.99; p-trend = 0.02).

CONCLUSION

Total flavonoid intake was not associated with POAG risk. Greater intakes of flavonols and monomeric flavanols and of tea showed suggestive modest associations with lower risk; these results need confirmation.

Rational Basis for Nutraceuticals in the Treatment of Glaucoma

BACKGROUND

Glaucoma, the second leading cause of blindness worldwide, is a chronic optic neuropathy characterized by progressive retinal ganglion cell (RGC) axons degeneration and death. Primary open-angle glaucoma (OAG), the most common type, is often associated with increased intraocular pressure (IOP), however other factors have been recognized to partecipate to the patogenesis of the optic neuropathy. IOP-independent mechanisms that contribute to the glaucoma-related neurodegeneration include oxidative stress, excitotoxicity, neuroinflammation, and impaired ocular blood flow. The involvement of several and diverse factors is one of the reasons for the progression of glaucoma observed even under efficient IOP control with the currently available drugs.

METHODS

Current research and online content related to the potential of nutritional supplements for limiting retinal damage and improving RGC survival is reviewed.

RESULTS

Recent studies have suggested a link between dietary factors and glaucoma risk. Particularly, some nutrients have proven capable of lowering IOP, increase circulation to the optic nerve, modulate excitotoxicity and promote RGC survival. However, the lack of clinical trials limit their current therapeutic use. The appropriate use of nutraceuticals that may be able to modify the risk of glaucoma may provide insight into glaucoma pathogenesis and decrease the need for, and therefore the side effects from, conventional therapies.

CONCLUSION

The effects of nutrients with anti-oxidant and neuroprotective properties are of great interest and nutraceuticals may offer some therapeutic potential although a further rigorous evaluation of nutraceuticals in the treatment of glaucoma is needed to determine their safety and efficacy.

The effect of flavonoids on visual function in patients with glaucoma or ocular hypertension: a systematic review and meta-analysis

BACKGROUND

Glaucoma is a leading cause of irreversible blindness worldwide. A major symptom of this pathology is the loss to the visual field in a peripheral to central pattern. Flavonoids are polyphenol compounds sourced from plants, commonly found in green tea, red wine and cocoa, and they have neuroprotective and antioxidant characteristics proposed to be advantageous within the context of glaucoma. Currently, the literature presents conflicting evidence regarding the effect of flavonoids on patients with glaucoma and ocular hypertension; hence a systematic review and meta-analysis was conducted.

METHOD

Databases included in our literature search were EMBASE (1980-present), MEDLINE Ovid, Alternative and Complementary Medicine Database (AMED), Cumulative Index to Nursing and Allied Health Literature (CINAHL) and Cochrane Central Register of Controlled Trials (CENTRAL). Meta-analysis was performed using RevMan 5 (Review Manager) 5 software, version 5.3 (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen). The primary outcomes were visual field mean deviation (MD) and intraocular pressure (IOP). Secondary outcomes were ocular blood flow and blood pressure (BP).

CONCLUSION

Meta-analyses showed that flavonoids have a promising role in improving visual function in patients with glaucoma and ocular hypertension (OHT), and appear to play a part in both improving and slowing the progression of visual field loss.

Posttranslational protein modifications by reactive nitrogen and chlorine species and strategies for their prevention and elimination

Proteins are subject to various posttranslational modifications, some of them being undesired from the point of view of metabolic efficiency. Prevention of such modifications is expected to provide new means of therapy of diseases and decelerate the process of aging. In this review, modifications of proteins by reactive nitrogen species and reactive halogen species, is briefly presented and means of prevention of these modifications and their sequelae are discussed, including the denitrase activity and inhibitors of myeloperoxidase.