Dietary flavonoids and the prevalence and 15-y incidence of age-related macular degeneration

Intake of Blueberries, Anthocyanins, and Risk of Eye Disease in Women

BACKGROUND

Blueberries and anthocyanins, their key bioactive component, may improve eye health. However, few long-term studies have examined blueberries and anthocyanins with cataract and age-related macular degeneration (AMD).

OBJECTIVES

To investigate the prospective association between blueberry and anthocyanin intake with incident cataract, total AMD, and visually significant AMD among middle-aged and older women.

METHODS

A total of 36,653 and 35,402 women initially free of AMD and cataract, respectively, aged ≥45 y from the Women's Health Study provided semiquantitative food frequency questionnaire data on blueberry intake categorized as none, 1-3 servings/mo, 1 serving/wk, or ≥2 servings/wk, plus a combined category of ≥1 serving/wk. Total anthocyanin intake and major subclasses were energy-adjusted and categorized into quintiles. Self-reported risk factors of eye disease were adjusted in multivariable hazard ratios (HRs) (95% confidence intervals [CIs]) of confirmed cataract, AMD, and visually significant AMD with mean follow-up of 11 y.

RESULTS

Among the participants, 10.5% consumed ≥1 serving/wk of blueberries, with mean total anthocyanin intake of 11.2 mg/d. Compared to no blueberry intake, women consuming 1-3 servings/mo, 1 serving/wk, and ≥2 servings/wk had corresponding multivariable HRs of total AMD of 0.90 (95% CI: 0.73, 1.11), 0.71 (95% CI: 0.50, 1.00), and 0.36 (95% CI: 0.14, 0.93) (Ptrend = 0.011); those consuming ≥1 servings/wk had an HR of 0.68 (95% CI: 0.47, 0.98). A similar magnitude of HRs were found for visually significant AMD (Ptrend = 0.012) but not for cataract. There were no significant associations between increasing total anthocyanin quintiles and total and visually significant AMD, but there was a modest inverse association with cataract (Ptrend = 0.022), driven by a 10% reduction in cataract in the upper 2 quintiles.

CONCLUSIONS

Greater blueberry intake significantly reduced total AMD, but not visually significant AMD or cataract. However, the magnitude of effect for visually significant AMD was similar to total AMD. There was a modest but significant inverse association between dietary anthocyanin intake with cataract but not AMD.

Insights into the nutritional prevention of macular degeneration based on a comparative topic modeling approach

Topic modeling and text mining are subsets of natural language processing (NLP) with relevance for conducting meta-analysis (MA) and systematic review (SR). For evidence synthesis, the above NLP methods are conventionally used for topic-specific literature searches or extracting values from reports to automate essential phases of SR and MA. Instead, this work proposes a comparative topic modeling approach to analyze reports of contradictory results on the same general research question. Specifically, the objective is to identify topics exhibiting distinct associations with significant results for an outcome of interest by ranking them according to their proportional occurrence in (and consistency of distribution across) reports of significant effects. Macular degeneration (MD) is a disease that affects millions of people annually, causing vision loss. Augmenting evidence synthesis to provide insight into MD prevention is therefore of central interest in this article. The proposed method was tested on broad-scope studies addressing whether supplemental nutritional compounds significantly benefit macular degeneration. Six compounds were identified as having a particular association with reports of significant results for benefiting MD. Four of these were further supported in terms of effectiveness upon conducting a follow-up literature search for validation (omega-3 fatty acids, copper, zeaxanthin, and nitrates). The two not supported by the follow-up literature search (niacin and molybdenum) also had scores in the lowest range under the proposed scoring system. Results therefore suggest that the proposed method's score for a given topic may be a viable proxy for its degree of association with the outcome of interest, and can be helpful in the systematic search for potentially causal relationships. Further, the compounds identified by the proposed method were not simultaneously captured as salient topics by state-of-the-art topic models that leverage document and word embeddings (Top2Vec) and transformer models (BERTopic). These results underpin the proposed method's potential to add specificity in understanding effects from broad-scope reports, elucidate topics of interest for future research, and guide evidence synthesis in a scalable way. All of this is accomplished while yielding valuable and actionable insights into the prevention of MD.

Association of dietary flavonoid intakes with prevalence of chronic respiratory diseases in adults

BACKGROUND AND AIMS

Flavonoids are a class of secondary plant metabolites that have been shown to have multiple health benefits, including antioxidant and anti-inflammatory. This study was to explore the association between dietary flavonoid consumption and the prevalence of chronic respiratory diseases (CRDs) in adults.

METHODS AND RESULTS

The six main types of flavonoids, including isoflavones, anthocyanidins, flavan-3-ols, flavanones, flavones, and flavonols, were obtained from the National Health and Nutrition Examination Survey (NHANES) 2007-2010 and 2017-2018 by the two 24-h recall interviews. The prevalence of CRDs, including asthma, emphysema, and chronic bronchitis, was determined through a self-administered questionnaire. The analysis included 15,753 participants aged 18 years or older who had completed a diet history interview. After adjustment for potential confounders, the inverse link was found with total flavonoids, anthocyanidins, flavanones, and flavones, with an OR (95%CI) of 0.86 (0.75-0.98), 0.84 (0.72-0.97), 0.80(0.69-0.92), and 0.85(0.73-0.98) for the highest group compared to the lowest group. WQS regression revealed that the mixture of flavonoids was negatively linked with the prevalence of CRDs (OR = 0.88 [0.82-0.95], P < 0.01), and the largest effect was mainly from flavanones (weight = 0.41). In addition, we found that flavonoid intake was negatively linked with inflammatory markers, and systemic inflammation significantly mediated the associations of flavonoids with CRDs, with a mediation rate of 12.64% for CRP (P < 0.01).

CONCLUSION

Higher flavonoid intake was related with a lower prevalence of CRDs in adults, and this relationship may be mediated through systemic inflammation.

A narrative review on dietary components and patterns and age-related macular degeneration

Age-related macular degeneration (AMD) is one of the most prevalent eye diseases among the ageing population worldwide. It is a leading cause of blindness in individuals over 55, particularly in industrialised Western countries. The prevalence of AMD increases with age, and genetic factors and environmental influences are believed to contribute to its development. Among the environmental factors, diet plays a significant role in AMD. This review explores the association between dietary components, dietary patterns and AMD. Various nutrients, non-nutrient substances and dietary models that have the potential to counteract oxidative stress and inflammation, which are underlying mechanisms of AMD, are discussed. Consuming fruits, vegetables, fish and seafood, whole grains, olive oil, nuts and low-glycaemic-index foods has been highlighted as beneficial for reducing the risk of AMD. Adhering to the Mediterranean diet, which encompasses these elements, can be recommended as a dietary pattern for AMD. Furthermore, the modulation of the gut microbiota through dietary interventions and probiotics has shown promise in managing AMD.

Role of flavonoids in age-related macular degeneration

A common eye disorder known as age-related macular degeneration (AMD) eventually results in blindness and vision loss. AMD has a complicated and poorly understood aetiology. The main pathological processes associated with AMD include oxidative damage, inflammation, and neovascularization. Flavonoids are naturally occurring bioactive substances with extensive distribution and antioxidant, anti-inflammatory, and neovascularization inhibitory properties. Several in vitro and in vivo AMD-related models pertinent to vision and this ocular ailment have been used to assess the mechanisms of action of various flavonoids. This article will discuss the research progress of flavonoids in AMD, especially the characteristics and mechanism of flavonoids in treating AMD.

What did we learn in 35 years of research on nutrition and supplements for age-related macular degeneration: a systematic review

The aim of this paper is to summarize all available evidence from systematic reviews, randomized controlled trials (RCTs) and comparative nonrandomized studies (NRS) on the association between nutrition and antioxidant, vitamin, and mineral supplements and the development or progression of age-related macular degeneration (AMD). The Cochrane Database of Systematic Reviews, Cochrane register CENTRAL, MEDLINE and Embase were searched and studies published between January 2015 and May 2021 were included. The certainty of evidence was assessed according to the GRADE methodology. The main outcome measures were development of AMD, progression of AMD, and side effects. We included 7 systematic reviews, 7 RCTs, and 13 NRS. A high consumption of specific nutrients, i.e. β-carotene, lutein and zeaxanthin, copper, folate, magnesium, vitamin A, niacin, vitamin B6, vitamin C, docosahexaenoic acid, and eicosapentaenoic acid, was associated with a lower risk of progression of early to late AMD (high certainty of evidence). Use of antioxidant supplements and adherence to a Mediterranean diet, characterized by a high consumption of vegetables, whole grains, and nuts and a low consumption of red meat, were associated with a decreased risk of progression of early to late AMD (moderate certainty of evidence). A high consumption of alcohol was associated with a higher risk of developing AMD (moderate certainty of evidence). Supplementary vitamin C, vitamin E, or β-carotene were not associated with the development of AMD, and supplementary omega-3 fatty acids were not associated with progression to late AMD (high certainty of evidence). Research in the last 35 years included in our overview supports that a high intake of specific nutrients, the use of antioxidant supplements and adherence to a Mediterranean diet decrease the risk of progression of early to late AMD.

Adherence to a Mediterranean Diet and Geographic Atrophy Enlargement Rate: Age-Related Eye Disease Study 2 Report 29

PURPOSE

To determine whether closer adherence to a Mediterranean diet was associated with altered speed of geographic atrophy (GA) enlargement.

DESIGN

Post hoc analysis of a cohort within the Age-Related Eye Disease Study 2.

PARTICIPANTS

The study included 1155 eyes (850 participants; mean age, 74.9 years) with GA at 2 or more visits.

METHODS

Geographic atrophy area was measured from color fundus photographs at annual visits. An alternative Mediterranean Diet index (aMedi) was calculated for each participant by food frequency questionnaire. Mixed-model regression of square root GA area was performed by aMedi.

MAIN OUTCOME MEASURES

Change in square root of GA area over time.

RESULTS

Over a mean follow-up of 3.1 years, the mean GA enlargement rate was 0.282 mm/year (95% confidence interval, 0.270-0.293). Enlargement was significantly slower in those with higher aMedi at 0.256 mm/year (0.236-0.276), 0.290 (0.268-0.311), and 0.298 (0.280-0.317; P = 0.008) for aMedi tertiles 3, 2, and 1, respectively. Of the 9 aMedi components considered separately, significant differences in enlargement rate were observed for 4 (whole fruit [P = 0.0004], red meat [P = 0.0002], alcohol [P = 0.006], and monounsaturated fatty acid to saturated fatty acid ratio ([MUFA:SFA] [P = 0.040]) but not for fish (P = 0.14). Enlargement was slower in those with higher whole fruit, lower red meat, moderate alcohol, and higher MUFA:SFA intake. In the 768 eyes with noncentral GA, aMedi was not associated with slower progression to central involvement: hazard ratios were 1.11 (0.83-1.48) and 0.95 (0.71-1.26) for tertiles 2 and 3, respectively.

CONCLUSIONS

A Mediterranean-type diet was associated with slower GA enlargement. Diet patterns like this may therefore lead to clinically meaningful delays in vision loss. Several components seemed to contribute most to this association in a pattern that differed from those most associated with decreased progression to GA. Hence, the Mediterranean diet is associated with protection against both faster progression to GA and faster enlargement of GA but for partially distinct reasons. These findings may help inform evidence-based dietary recommendations. Understanding the mechanisms responsible may provide insights into the underlying biology and lead to the development of nutritional supplements.

(–)-Epicatechin Provides Neuroprotection in Sodium Iodate-Induced Retinal Degeneration

Oxidative stress, mitochondrial impairment, and pathological amyloid beta (Aβ) deposition are involved in the pathogenesis of dry age-related macular degeneration (AMD). The natural flavonoid (–)-epicatechin (EC) is known to be an antioxidant and neuroprotective compound. Whether EC plays a therapeutic role in AMD is unknown. In this work, we aimed to assess the efficacy and molecular mechanisms of EC against sodium iodate (NaIO₃)-induced retinal degeneration in C57BL/6 mice via bioinformatic, morphological, and functional methods. We demonstrated that EC had no toxic effects on the retina and could ameliorate retinal deformation and thinning. EC treatment prevented outer retinal degeneration, reduced drusen-like deposits, increased b-wave amplitude in electroretinography, blocked retinal gliosis, and increased the number and quality of mitochondria. Importantly, EC increased the protein expression of OPA1 and decreased the expression of PINK1, indicating the role of EC in mitochondrial fusion that impaired by NaIO₃. Moreover, EC downregulated APP and TMEM97 levels, upregulated PGRMC1 levels, and reduced subretinal Aβ accumulation. This study illustrated that EC, which may become a promising therapeutic strategy for AMD, prevented NaIO₃-induced retinal degeneration, and this improvement may be associated with the mitochondrial quality control and the TMEM97/PGRMC1/Aβ signaling pathway.

Dietary Flavonoid Intake and Chronic Sensory Conditions: A Scoping Review

Dietary flavonoids have antioxidant, anti-inflammatory, and vascular health benefits, which align with the proposed pathophysiology of age-related eye conditions and hearing problems (hearing loss and tinnitus). This scoping review is based on Arksey and O’Malley’s six-stage framework and aims to summarise current evidence on the association between the dietary flavonoid intake and chronic sensory conditions in adults, and to identify the research gaps in this area. Eligible studies were identified by searching MEDLINE, EMBASE PsycINFO via the OVID platform, and Google Scholar, as well as manually searching the reference lists of the eligible articles. The inclusion criteria included: articles with full-text access, written in the English language, and focused on chronic sensory conditions and dietary flavonoid intake in an adult population. Studies focused on flavonoid supplements were excluded. Ten studies were included in this review. The evidence suggests that the flavonoid subclass, flavonols, are protective against eye conditions, including age-related macular degeneration, cataract, and glaucoma. There is insufficient evidence to support an association with hearing loss or tinnitus. Overall, dietary flavonol intake appears to be protective against some chronic eye conditions. However, for most eye and hearing-related conditions, only one study was identified. Thus, there is a need for more recent high-quality research to be conducted to confirm any significant associations.

Oxidative stress and visual system: a review

Different types of tissues respond differently to the action of oxidative stress. The visual system is very sensitive to oxidative action due to continuous exposure to light. In consideration of the growing interest of scientific studies towards various compounds endowed with antioxidant and anti-inflammatory properties, we performed a review of the literature focusing on the use of some antioxidant molecules for the treatment of conditions affecting the visual system. In this study, we focused on the ability of two antioxidant agents, the small molecule α-lipoic acid (ALA) and the enzyme superoxide dismutase (SOD), to influence the neurodegenerative physiological processes related to aging and oxidative stress affecting the ocular segment. The literature data report that ALA and SOD can protect against neurodegenerative effects both the optic nerve and retina and, if administered together, they are able to lower the levels of oxidative stress, thus preventing neurodegeneration and reducing the apoptotic process.

Prevalence of Vitreoretinal Interface Disorders in an Australian Population

Purpose

To describe the prevalence, risk factors, and associations of vitreoretinal interface (VRI) abnormalities in a population-based study of older adults.

Design

Cross-sectional analysis of cohort study participants.

Participants

Of the 1149 participants (mean age, 76.1 ± 6.9 years) in the 15-year Blue Mountains Eye Study follow-up examination from 2007 through 2009, 905 (1791 eyes) had gradable time-domain or spectral-domain OCT scans of the macula from at least 1 eye.

Methods

OCT scans were graded according to the International Vitreomacular Traction Study Group classification system of VRI abnormalities. Best-corrected visual acuity (BCVA) was recorded.

Main Outcome Measures

Prevalence of VRIs.

Results

Overall, 451 participants showed any VRI abnormality (49.8%). Prevalence of VRI abnormality by person was: vitreomacular adhesion (VMA), 33.6%; vitreomacular traction (VMT), 1.6%; epiretinal membrane (ERM), 21.4%; full-thickness macular hole (FTMH), 0.7%; and lamellar macular hole (LMH), 0.7%. Twenty-two percent of VMAs were focal, and 78% were broad based; 76% of VMTs were focal, and 24% were broad based. All FTMHs observed were large (>400 μm), with mean aperture size of 573 μm (range, 459–771 μm). Increased age was associated with higher ERM and lower VMA prevalence (P < 0.001 for both). Pseudophakia and myopia were associated with ERM (age- and sex-adjusted odds ratios [ORs], 1.48 [95% confidence interval (CI), 1.01–2.17] and 1.72 [95% CI, 1.05–2.81], respectively). Moderate or severe ERM and FTMH were associated with worse BCVA of 9.2 Early Treatment Diabetic Retinopathy Study (ETDRS) letters (95% CI, 3.4–15.0 ETDRS letters; P = 0.008) and 26.0 ETDRS letters (95% CI, 10.9–41.1 ETDRS letters; P = 0.001), respectively.

Conclusions

The prevalence of VRI abnormalities is high in older individuals. Epiretinal membrane was associated with increasing age, pseudophakia, and myopia. Epiretinal membrane and FTMH may account for significant visual loss in the affected eye. This study provided useful population-based data on the prevalence of VRI abnormalities in older individuals.

Dietary flavonoids are associated with longitudinal treatment outcomes in neovascular age-related macular degeneration

PURPOSE

To assess whether dietary intake of flavonoids are associated with longitudinal treatment outcomes of patients with neovascular age-related macular degeneration (nAMD).

METHODS

547 participants with nAMD were recruited at baseline, 494 were followed-up after receiving 12 months of anti-vascular endothelial growth factor (anti-VEGF) therapy. Baseline dietary intake of flavonoids was determined using a validated food frequency questionnaire. At follow-up, presence of intra-retinal and sub-retinal fluid (IRF and SRF), retinal pigment epithelium detachment and measurements of central macular thickness (CMT) were recorded from optical coherence tomography scans. Visual acuity (VA) was documented using LogMAR charts.

RESULTS

Participants in the first tertile of intake of the flavonol quercetin, and the flavan-3-ols epigallocatechin-3-gallate and epigallocatechin had significantly worse vision than participants in the third tertile-multivariable-adjusted least square (LS) mean VA: 14.68 vs. 19.53 (p = 0.04); 14.06 vs. 18.89 (p = 0.04); 13.86 vs. 18.86 (p = 0.03), respectively. Participants in the first compared to the third tertile of flavan-3-ol, epigallocatechin-3-gallate and epigallocatechin intake all had a twofold higher risk of IRF, multivariable-adjusted p trend of: 0.03, 0.01 and 0.02, respectively. The first vs. the third tertile of tea intake had significantly worse vision (LS mean VA: 13.49 vs. 19.04, p = 0.02), increased risk of IRF (OR 2.13, 95% CI 1.18-3.85) and greater mean CMT (279.59 μm vs. 256.52 μm, p = 0.04).

CONCLUSIONS

Higher intakes of dietary flavonoids, specifically flavonols and flavan-3-ols, could be associated with better long-term treatment outcomes in nAMD patients receiving anti-VEGF therapy. Confirmation of these associations in interventional studies could result in promising new therapeutic approaches to the treatment of nAMD.

Oxidative stress as a therapeutic target for the prevention and treatment of early age-related macular degeneration

Age-related macular degeneration, the leading cause of irreversible visual loss among older adults in developed countries, is a chronic, multifactorial, and progressive disease with the development of painless, central vision loss. Retinal pigment epithelial cell dysfunction is a core change in age-related macular degeneration that results from aging and the accumulated effects of genetic and environmental factors that, in part, is both caused by and leads to oxidative stress. In this review, we describe the role of oxidative stress, the cytoprotective oxidative stress pathways, and the impact of oxidative stress on critical cellular processes involved in age-related macular degeneration pathobiology. We also offer targeted therapy that may define how antioxidant therapy can either prevent or improve specific stages of age-related macular degeneration.

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.

Mitochondrial Dysfunction as a Novel Target for Neuroprotective Nutraceuticals in Ocular Diseases

The eyes require a rich oxygen and nutrient supply; hence, the high-energy demand of the visual system makes it sensitive to oxidative stress. Excessive free radicals result in mitochondrial dysfunction and lead to retinal neurodegeneration, as an early stage of retinal metabolic disorders. Retinal cells are vulnerable because of their coordinated interaction and intricate neural networks. Nutraceuticals are believed to target multiple pathways and have shown neuroprotective benefits by scavenging free radicals and promoting mitochondrial gene expression. Furthermore, encouraging results demonstrate that nutraceuticals improve the organization of retinal cells and visual functions. This review discusses the mitochondrial impairments of retinal cells and the mechanisms underlying the neuroprotective effects of nutraceuticals. However, some unsolved problems still exist between laboratory study and clinical therapy. Poor bioavailability and bioaccessibility strongly limit their development. A new delivery system and improved formulation may offer promise for health care applications.

Adherence to the Mediterranean Diet and Progression to Late Age-Related Macular Degeneration in the Age-Related Eye Disease Studies 1 and 2

PURPOSE

To determine whether closer adherence to a Mediterranean diet (and its individual components) was associated with altered risk of progression to late age-related macular degeneration (AMD) and large drusen. Additional objectives were to assess interactions with AMD genotype.

DESIGN

Retrospective analysis of 2 controlled clinical trial cohorts: Age-Related Eye Disease Study (AREDS) and AREDS2.

PARTICIPANTS

Eyes with no late AMD at baseline in AREDS participants (n = 4255) and AREDS2 participants (n = 3611): total of 13 204 eyes (7756 participants). Mean age was 71 years (standard deviation, 6.6); 56.5% were female.

METHODS

Color fundus photographs were collected at annual study visits and graded centrally for late AMD. The modified Alternative Mediterranean Diet Index (aMedi) score was calculated for each participant from food frequency questionnaires.

MAIN OUTCOME MEASURES

Progression to late AMD, geographic atrophy (GA), and neovascular AMD; progression to large drusen.

RESULTS

Over a median follow-up of 10.2 years, of the 13 204 eyes, 34.0% progressed to late AMD. Hazard ratios (HRs) for progression in aMedi tertile 3 versus 1 were 0.78 (95% confidence interval [CI], 0.71-0.85, P < 0.0001) for late AMD, 0.71 (0.63-0.80, P < 0.0001) for GA, and 0.84 (0.75-0.95, P = 0.005) for neovascular AMD. For fish consumption, HRs for late AMD in quartile 4 versus 1 were 0.69 (0.58-0.82, P < 0.0001; AREDS) and 0.92 (0.78-1.07, P = 0.28; AREDS2). In AREDS, both aMedi and its fish component interacted with CFH rs10922109 for late AMD (P = 0.01 and P = 0.0005, respectively); higher aMedi and fish intake were each associated with decreased risk only in participants with protective alleles. In separate analyses (n = 5029 eyes of 3026 AREDS participants), the HR for progression to large drusen in aMedi tertile 3 versus 1 was 0.79 (0.68-0.93, P = 0.004).

CONCLUSIONS

Closer adherence to a Mediterranean-type diet was associated with lower risk of progression to late AMD and to large drusen. The signal was greater for GA than neovascular AMD. Fish intake contributed to this protective association. CFH genotype strongly influenced these relationships. These findings may help inform evidence-based dietary recommendations.

Associations between dietary flavonoids and retinal microvasculature in older adults

PURPOSE

In this study, we assessed whether there are independent associations between dietary total flavonoid intake and major flavonoid classes with retinal arteriolar and venular calibre.

METHODS

Blue Mountains Eye Study participants aged 49+ years who had complete data on diet and retinal vessel measures were analysed (n = 2821). Dietary intake was assessed using a semi-quantitative Food-Frequency Questionnaire (FFQ). Flavonoid content of foods in the FFQ was estimated using the US Department of Agriculture Flavonoid, Isoflavone and Proanthocyanidin databases. Fundus photographs were taken and retinal vascular calibre was measured using validated computer-assisted techniques. The associations of intake of dietary flavonoids with retinal vessel calibre were examined in linear regression models and general linear model.

RESULTS

The highest quartile of intake was compared with the lowest quartile using multivariable-adjustment models. Participants with the highest proanthocyanidin intake had narrower retinal venules (223.9 ± 0.62 versus 226.5 ± 0.63, respectively; P_trend = 0.01); and the highest isoflavone intake was associated with wider retinal arterioles (188.1 ± 0.55 versus 186.3 ± 0.56, respectively; P_trend = 0.01). The highest apple/pear consumption (a dietary source of catechin) was associated with narrower retinal venules (223.8 ± 0.57 versus 226.1 ± 0.52; P_trend = 0.01) and wider retinal arterioles (187.9 ± 0.51 versus 186.2 ± 0.51; P_trend = 0.02). Further, participants who were in the highest versus lowest quartile of chocolate consumption had ~ 2.1 μm narrower retinal venules (multivariable-adjusted P = 0.03).

CONCLUSIONS

This study shows that higher intakes of specific flavonoid subclasses are associated with a favourable retinal microvascular profile. Greater consumption of flavonoid-rich apples/pears and chocolate was also associated with beneficial variations in retinal vascular calibre.

Isoflavones as Ah Receptor Agonists in Colon-Derived Cell Lines: Structure-Activity Relationships

Many of the protective responses observed for flavonoids in the gastrointestinal track resemble aryl hydrocarbon receptor (AhR)-mediated effects. Therefore, we examined the structure-activity relationships of isoflavones and isomeric flavone and flavanones as AhR ligands on the basis of their induction of CYP1A1, CYP1B1, and UGT1A1 gene expression in colon cancer Caco2 cells and young adult mouse colonocyte (YAMC) cells. Caco2 cells were significantly more Ah-responsive than YAMC cells, and this was due, in part, to flavonoid-induced cytotoxicity in the latter cell lines. The structure-activity relationships for the flavonoids were complex and both response and cell context specific; however, there was significant variability in the AhR activities of the isomeric substituted isoflavones and flavones. For example, 4',5,7-trihydroxyisoflavone (genistein) was AhR-inactive whereas 4',5,7-trihydroxyflavone (apigenin) induced CYP1A1, CYP1B1, and UGT1A1 in Caco2 cells. In contrast, both 5,7-dihydroxy-4-methoxy substituted isoflavone (biochanin A) and flavone (acacetin) induced all three AhR-responsive genes; 4',5,7-trimethoxyisoflavone was a potent AhR agonist, and the isomeric flavone was AhR-inactive. These results coupled with simulation studies modeling flavonoid interaction within the AhR binding pocket demonstrate that the orientation of the substituted phenyl ring at C-2 (flavones) or C-3 (isoflavones) on the common 4-H-chromen-4-one ring strongly influences the activities of isoflavones and flavones as AhR agonists.

Systematic Review on Polyphenol Intake and Health Outcomes: Is there Sufficient Evidence to Define a Health-Promoting Polyphenol-Rich Dietary Pattern?

Growing evidence support association between polyphenol intake and reduced risk for chronic diseases, even if there is a broad debate about the effective amount of polyphenols able to exert such protective effect. The present systematic review provides an overview of the last 10-year literature on the evaluation of polyphenol intake and its association with specific disease markers and/or endpoints. An estimation of the mean total polyphenol intake has been performed despite the large heterogeneity of data reviewed. In addition, the contribution of dietary sources was considered, suggesting tea, coffee, red wine, fruit and vegetables as the main products providing polyphenols. Total flavonoids and specific subclasses, but not total polyphenols, have been apparently associated with a low risk of diabetes, cardiovascular events and all-cause mortality. However, large variability in terms of methods for the evaluation and quantification of polyphenol intake, markers and endpoints considered, makes it still difficult to establish an evidence-based reference intake for the whole class and subclass of compounds. Nevertheless, the critical mass of data available seem to strongly suggest the protective effect of a polyphenol-rich dietary pattern even if further well targeted and methodologically sound research should be encouraged in order to define specific recommendations.

Consumption of eggs and the 15-year incidence of age-related macular degeneration

BACKGROUND AND AIMS

A naturally rich source of lutein and zeaxanthin are eggs. There is scarce epidemiological data on the temporal association between total egg consumption and age-related macular degeneration (AMD) incidence. We aimed to establish the prospective and independent association between consumption of eggs with the incidence of AMD over a 15-year follow-up.

METHODS

In this population-based cohort study of 3,654 participants aged 49 + years examined at baseline, 2034 participants had complete information on baseline egg consumption and AMD signs over 15 years. AMD was determined from retinal photographs. Egg consumption was assessed using a semi-quantitative food-frequency questionnaire. Total egg intake was calculated through summing up intakes in all forms e.g. boiled, poached, fried, scrambled and/or omelette. We summarized total egg consumption into the following categories: ≤1 egg/week; 2-4 eggs/week; 5-6 eggs/week; and ≥1 egg/day.

RESULTS

At baseline, participants who consumed 2-4 eggs/week compared to those who consumed ≤1 egg/week (reference group) had reduced risk of incident late-stage AMD after 15 years: multivariable-adjusted odds ratio, OR, 0.51 (95% confidence intervals, CI, 0.28-0.92). Participants who consumed 2-4 eggs/week versus ≤1 egg/week at baseline had 62% reduced risk of developing neovascular AMD. Among those whose AMD onset was at or before the 10-year follow-up, consumption of 2-4 and 5-6 eggs/week was associated with 54% and 65% reduced risk of incident late AMD, respectively. When analyzed as a dichotomized variable, participants who consumed >1 egg/week versus ≤1 egg/week at baseline, had 46% reduced risk of developing late-stage AMD 15 years later: multivariable-adjusted OR 0.54 (95% CI 0.3-0.90). Non-significant associations were observed between egg consumption and incident early AMD.

CONCLUSIONS

Our findings suggest that moderate consumption of eggs significantly reduces the risk of developing incident late-stage AMD over 15 years.

Health Benefits of Polyphenols and Carotenoids in Age-Related Eye Diseases

Oxidative stress and inflammation play a critical role in the initiation and progression of age-related ocular abnormalities as cataract, glaucoma, diabetic retinopathy, and macular degeneration. Therefore, phytochemicals with proven antioxidant and anti-inflammatory activities, such as carotenoids and polyphenols, could be of benefit in these diseases. We searched PubMed and Web of Science databases for original studies investigating the benefits of different carotenoids and polyphenols in age-related ophthalmic diseases. Our results showed that several polyphenols (such as anthocyanins, Ginkgo biloba, quercetin, and resveratrol) and carotenoids (such as lutein, zeaxanthin, and mezoxanthin) have shown significant preventive and therapeutic benefits against the aforementioned conditions. The involved mechanisms in these findings include mitigating the production of reactive oxygen species, inhibiting the tumor necrosis factor-α and vascular endothelial growth factor pathways, suppressing p53-dependent apoptosis, and suppressing the production of inflammatory markers, such as interleukin- (IL-) 8, IL-6, IL-1a, and endothelial leucocyte adhesion molecule-1. Consumption of products containing these phytochemicals may be protective against these diseases; however, adequate human data are lacking. This review discusses the role and mechanisms of polyphenols and carotenoids and their possible synergistic effects on the prevention and treatment of age-related eye diseases that are induced or augmented by oxidative stress and inflammation.

Relationship of dietary nitrate intake from vegetables with cardiovascular disease mortality: a prospective study in a cohort of older Australians

PURPOSE

Short-term trials indicate inorganic nitrate and nitrate-rich vegetables may have vascular health benefits. However, few observational studies have explored the relationship between nitrate intake and long-term cardiovascular disease (CVD) outcomes. The primary aim of this study was to investigate the association of nitrate intake from vegetables with CVD mortality in a sample of older Australians.

METHODS

A subgroup of participants without diabetes or major CVD at baseline (1992-1994) were included from the Blue Mountains Eye Study, a population-based cohort study of men and women aged ≥ 49 years. Diets were evaluated using a validated food frequency questionnaire at baseline, 5 years and 10 years of follow-up. Vegetable nitrate intake was estimated using a comprehensive vegetable nitrate database. Cox proportional hazard regression was used to explore the association between vegetable nitrate intake and CVD mortality.

RESULTS

During 14 years of follow-up, 188/2229 (8.4%) participants died from CVD. In multivariable-adjusted analysis, participants in quartile 2 [69.5-99.6 mg/day; HR 0.53 (95% CI 0.35, 0.82)], quartile 3 [99.7-137.8 mg/day; HR 0.51 (95% CI 0.32, 0.80)], and quartile 4 [> 137.8 mg/day; HR 0.63 (95% CI 0.41, 0.95)] of vegetable nitrate intake had lower hazards for CVD mortality compared to participants in quartile 1 (< 69.5 mg/day).

CONCLUSIONS

In older Australian men and women, vegetable nitrate intake was inversely associated with CVD mortality, independent of lifestyle and cardiovascular risk factors. These findings confirm a recent report that intake of vegetable nitrate lowers the risk of CVD mortality in older women and extend these findings to older men.