Lutein, Zeaxanthin and Meso-zeaxanthin Supplementation Associated with Macular Pigment Optical Density

Macular Pigment Changes and Visual Recovery Following Successful Full-Thickness Macular Hole Closure Using the Inverted Flap Technique

Objectives: This study aimed to assess the role of macular pigment optical density (MPOD) in patients with a full-thickness macular hole (FTMH) compared to healthy controls, evaluating postoperative changes in MPOD and exploring potential correlations with visual outcomes. Methods: This prospective, cross-sectional, comparative study included 16 eyes from FTMH patients who achieved anatomical hole closure following pars plana vitrectomy with the inverted ILM flap technique. Each eye underwent a comprehensive ophthalmologic examination, including BCVA and intraocular pressure measurements, anterior segment evaluation, fundus examination, and macular assessment with Enhanced Depth Imaging Optical Coherence Tomography (EDI-OCT, Spectralis, Heidelberg Engineering Inc., Heidelberg, Germany). Macular pigment optical density (MPOD) was measured using one-wavelength reflectometry (Visucam 200, Zeiss Meditec, Jena, Germany). These evaluations were conducted preoperatively and at 1, 3, and 6 months postoperatively to assess changes over time and correlate MPOD with visual outcomes. Results: Significant baseline differences were observed between FTMH patients and controls for BCVA, mean MPOD, maximum MPOD, and MPOD volume (p < 0.05). Postoperative BCVA improved significantly (p = 0.0011), with a notable increase in MPOD volume at 6 months (p = 0.01). A positive correlation was found between BCVA improvement and MPOD volume increase (r = 0.739; p = 0.002). Conclusions: In conclusion, MPOD measurement may serve as a valuable addition to the follow-up of FTMH surgery, providing insights into photoreceptor function and macular metabolic activity, potentially correlating with visual recovery. Further longitudinal studies are needed to clarify its relationship with clinical variables, such as metamorphopsia and OCT microstructural findings.

Nutritional Genomics: Implications for Age-Related Macular Degeneration

Background: Age-related macular degeneration (AMD) is a leading cause of vision loss in older individuals, driven by a multifactorial etiology involving genetic, environmental, and dietary factors. Nutritional genomics, which studies gene-nutrient interactions, has emerged as a promising field for AMD prevention and management. Genetic predispositions, such as variants in CFH, C3, C2/CFB, APOE, and oxidative stress pathways, significantly affect the risk and progression of AMD. Methods: This narrative review synthesizes findings from randomized controlled trials and recent advances in nutritional genomics research. It examines the interplay between genetic predispositions and dietary interventions, exploring how personalized nutritional strategies can optimize AMD management. Results and Discussion: The AREDS and AREDS2 trials demonstrated that supplements, including vitamins C, E, zinc, copper, lutein, and zeaxanthin, can reduce the progression to advanced AMD. Nutritional interventions tailored to genetic profiles show promise: CFH risk alleles may enhance zinc supplementation's anti-inflammatory effects, while APOE variants influence the response to omega-3 fatty acids. Adjusting carotenoid intake, such as lutein and zeaxanthin, based on genetic susceptibility exemplifies emerging precision nutritional approaches. Ongoing research seeks to integrate nutrigenomic testing into clinical settings, enabling clinicians to tailor interventions to individual genetic profiles. Conclusions: Further studies are needed to assess the long-term effects of personalized interventions, investigate additional genetic variants, and develop tools for clinical implementation of nutrigenomics. Advancing these strategies holds the potential to improve patient outcomes, optimize AMD management, and pave the way for precision nutrition in ophthalmology.

Beneficial Effects of Micronutrient Supplementation in Restoring the Altered Microbiota and Gut-Retina Axis in Patients with Neovascular Age-Related Macular Degeneration-A Randomized Clinical Trial

Background/Objectives: Age-related macular degeneration (AMD) is a leading cause of visual impairment in the elderly and is characterized by a multifactorial etiology. Emerging evidence points to the potential involvement of the gut-retina axis in AMD pathogenesis, prompting exploration into novel therapeutic strategies. This study aims to investigate the effects of some micronutrients (such as lutein and zeaxanthin) and saffron (as a supplement)-known for their anti-inflammatory properties-on ophthalmological and microbial parameters in neovascular AMD (nAMD) patients. Methods: Thirty naive nAMD patients were randomized to receive daily micronutrient supplementation alongside anti-VEGF (vascular endothelial growth factor) therapy, or anti-VEGF treatment alone, over a 6-month period, with comparisons made to a healthy control (HC) group (N = 15). Ophthalmological assessments, biochemical measurements, and stool samples were obtained before and after treatment. Gut microbiota (GM) characterization was performed using 16S rRNA sequencing, while short-chain fatty acids (SCFAs), medium-chain fatty acids (MCFAs), and long-chain fatty acids (LCFAs) were analyzed with a gas chromatography-mass spectrometry protocol. Results: Compared to HC, nAMD patients exhibited reduced GM alpha diversity, altered taxonomic composition, and decreased total SCFA levels, in addition to elevated levels of proinflammatory octanoic and nonanoic acids. Micronutrient supplementation was associated with improved visual acuity relative to the group treated with anti-VEGF alone, along with a decrease in the total amount of MCFAs, which are metabolites known to have adverse ocular effects. Conclusions: In conclusion, despite certain limitations-such as the limited sample size and the low taxonomic resolution of 16S rRNA sequencing-this study highlights compositional and functional imbalances in the GM of nAMD patients and demonstrates that micronutrient supplementation may help restore the gut-retina axis. These findings suggest the therapeutic potential of micronutrients in enhancing ocular outcomes for nAMD patients, underscoring the complex interaction between GM and ocular health.

Characterization of the interindividual variability of lutein and zeaxanthin concentrations in the adipose tissue of healthy male adults and identification of combinations of genetic variants associated with it

Lutein (L) and zeaxanthin (Z) are involved in visual function and could prevent age-related macular degeneration and chronic diseases and improve cognitive performances. Adipose tissue is the main storage site for these xanthophylls (Xanth). The factors affecting their concentrations in this tissue remain poorly understood but in animal models, genetic variations in apolipoprotein E and β-carotene oxygenase 2 have been associated with adipose tissue L concentration. Therefore, the aims of this study were to better characterize the interindividual variability of adipose tissue Xanth concentration and to identify single nucleotide polymorphisms (SNPs) associated with it. Periumbilical subcutaneous adipose tissue samples were collected on 6 occasions in 42 healthy adult males and L and Z concentrations were measured by HPLC. Participants had their whole genome genotyped and the associations of 3589 SNPs in 49 candidate genes with the concentrations of L and Z were measured. Mean L and Z concentrations were 281 ± 27 and 150 ± 14 nmol g-1 proteins, respectively. There was no significant correlation between plasma and adipose tissue Xanth concentrations, although the correlation for L approached significance (Pearson's r = 0.276, p = 0.077). Following univariate filtering, 109 and 97 SNPs were then entered into a partial least squares regression analysis to identify the combination of SNPs that explained best adipose tissue concentration of L and Z, respectively. A combination of 7 SNPs in ELOVL5, PPARG, ISX and ABCA1, explained 58% of the variability in adipose tissue L concentration while 11 SNPs located in or near PPARG, ABCA1, ELOVL5, CXCL8, IRS1, ISX, MC4R explained 53% of the variance in adipose tissue Z concentration. This suggests that some genetic variations influence the concentrations of these Xanth in adipose tissue and could therefore indirectly influence the health effects of these compounds. Clinical Trial Registry: https://ClinicalTrials.gov registration number NCT02100774.

A mechanistic review on growing multiple therapeutic applications of lutein and its global market research

Lutein is a naturally occurring carotenoid synthesized by plants and algae that has a beneficial effect on several biological processes and associated ailments. Its immediate application is in ophthalmology, where it significantly lowers the incidences of age-related macular degeneration (AMD). It also has anti-inflammatory action, treatment of diabetic retinopathy, and cataracts, and enhancement of visual contrast. To critically assess lutein biosynthesis, therapeutic applicability, and market research literature. We have discussed its theoretical frameworks, experimental evidence, limitations, as well as clinical trial results, and future research prospects. The literature for this review article was mined and compiled by collecting and analyzing articles from several databases, including ScienceDirect, Google Scholar, PubMed, Wiley Online Library, Patentscope, and ClinicalTrials.gov published until March 30, 2022. Patent publications were identified using the search terms like IC:(C07C67/56) AND EN_AB:(lutein) OR EN_TI:(lutein) OR EN_AB:(extraction) OR EN_TI:(process). According to the literature, lutein is an essential nutrient given that it cannot be synthesized in the human body and acts as an antioxidant, affecting AMD, diabetic retinopathy, Rheumatic diseases, inflammation, and cancer. Due to inadequate production and laborious extraction, lutein is expensive despite its high demand and applicability. Market research predicts a 6.3% compound annual growth rate for lutein by 2032. Optimizing lutein extraction for high yield and purity is necessary. Lutein has proven applicability in various ailments as well as cosmetics that can be developed as a candidate drug for various diseases discussed in the review.

Lutein Production and Extraction from Microalgae: Recent Insights and Bioactive Potential

Microalgae have been reported to be excellent producers of bioactive molecules. Lutein is a pigment reported to have various beneficial effects for humans, and especially for eye well-being. In the current review, we summarize various methods that have been developed to optimize its extraction and bioactivities reported for human health. Several protective effects have been reported for lutein, including antioxidant, anticancer, anti-inflammatory, and cardioprotective activity. This review also reports attempts to increase lutein production by microalgae by changing culturing parameters or by using pilot-scale systems. Genetic engineering lutein production is also discussed. Considering the increasing aging of the worldwide population will create an increased need for lutein, a viable economic and eco-sustainable method to produce lutein is needed to face this market demand.

Newly developed dietary assessment tools for lutein and zeaxanthin are correlated with 24-hour diet recalls, but are not a valid measure of intake in Australian and United Kingdom adults

Habitual dietary intake measurement of carotenoids lutein and zeaxanthin (L/Z) has often been omitted or attempted with tools of unknown validity in past research. It was hypothesized that the dietary assessment tool, the L/Z screener, developed as part of this study, would be valid with agreement within 0.25 mg/day when compared against multiple 24-hour diet recalls in healthy Australian and United Kingdom adults. Two screeners with 91 food items were developed, 1 with a recall timeframe of a month and the other a week. Over 4 weeks, 56 Australian and 47 United Kingdom participants completed 4 weekly screeners, 2 monthly screeners, and eight 24-hour diet recalls. Validity was assessed through Bland-Altman plot analysis. L/Z intake measured by all tools was significantly correlated, with correlation coefficients from 0.58 to 0.83. Despite these correlations, the screeners were not valid, with poor Bland-Altman plot agreement when compared with the diet recalls. The Australian weekly screener performed best, demonstrating a mean difference of 0.51 mg/day and 95% limits of agreement between -1.46 mg/day and 2.49 mg/day of L/Z intake. Baby spinach, broccoli, and pumpkin provided the greatest proportion of L/Z intake. The low validity may be explained by high rates of misestimation or missed capture of moderate to high L/Z containing foods such as baby spinach. Prior research reliant on correlational statistics for L/Z tool validity should be interpreted with caution, and future screener development should prioritize accurate capture of high contribution foods.

Innovative Food Safety Approaches and Nutraceuticals to Promote Children's Health on Future Outbreaks with the Reflection of COVID-19

After the COVID-19 pandemic, innovative methods have emerged for the management of food safety, child nutrition has become more important than ever, and increasing attention has been paid to the consequences of COVID-19. For instance, since SARS-CoV-2 is an animal-based zoonotic virus, there is a changing trend in consumer preferences from conventional meat products to cultured meat and vegan supplementation. Due to the effects mentioned, this chapter provides strategic guidance on novel foods, food safety innovations, and novel health and safety procedures in public places such as restaurants or bars. There are also long-term health impacts on children in the aftermath of COVID-19. Since the risk of myopia is one of the important long-term effects to be considered, trending nutritional immunology approaches are presented to reduce emerging problems in child eye health. The enhancement of immune system remains problematic for many children considering that they cannot use the COVID-19 vaccine. Therefore, this chapter also emphasizes the importance of breastfeeding on the side effects of viral infections and new supplements, such as probiotic drops, to improve children's and babies' immune health. Additionally, efforts should be undertaken to improve nanoencapsulation techniques to prepare for future epidemics and pandemics. Nanomaterial-supported nutraceuticals, nanoencapsulation of functional ingredients or their nanoparticles, and nano-combination of phytochemicals, fatty acids, or probiotics should be investigated to improve the immunity of children. In this sense, detailed further research in this area needs to be adapted to innovative technologies for the treatment of infants and children against future zoonotic viruses.

Effect of xanthophyll-rich food and supplement intake on visual outcomes in healthy adults and those with eye disease: a systematic review, meta-analysis, and meta-regression of randomized controlled trials

CONTEXT

Xanthophyll intake is known to improve eye health; however, its benefits on visual outcomes have not been systematically studied, particularly in a population with eye diseases.

OBJECTIVE

A systematic review, meta-analysis, and meta-regression were conducted to investigate the effect of xanthophyll intake on visual outcomes, and further subgroup analysis was performed on the basis of eye disease status.

DATA SOURCES

The PubMed, Scopus, Embase, CINAHL, Cochrane, and Web of Science databases were searched, and relevant randomized controlled trials were identified.

DATA EXTRACTION

For systematic review, meta-analysis, and meta-regression, 43, 25, and 21 articles were selected, respectively.

DATA ANALYSIS

Xanthophyll intake enhanced macular pigment optical density (MPOD) for both heterochromatic flicker photometry (weighted mean difference [WMD], 0.05; 95% confidence interval [CI], 0.03-0.07) and autofluorescence imaging (WMD, 0.08; 95%CI, 0.05-0.11) measurements and decreased photostress recovery time (WMD, -2.35; 95%CI, -4.49 to -0.20). While enhancement in visual acuity logarithm of the minimum angle of resolution was observed in response to the xanthophyll-rich food and supplement intake only for patients with eye disease (WMD, -0.04; 95%CI, -0.07 to -0.01). Meta-regression showed a positive correlation between change in MPOD (heterochromatic flicker photometry) and the corresponding change in serum lutein levels (regression coefficient = 0.068; P = 0.00).

CONCLUSION

Intake of xanthophyll-rich food or supplements can improve eye health. Additional improvement in visual acuity was observed in patients with eye disease. A positive association between MPOD and serum lutein level, while absent with dietary xanthophyll intake, suggests the importance of bioavailability when examining the effect of xanthophyll on eye health.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42021295337.

Impacts of regular consumption of grapes on macular pigment accumulation in Singapore older adults: a randomized controlled trial

Background: Oxidative stress is a key risk factor for visual impairment and consuming dietary antioxidant-rich foods may help in managing visual impairments. However, a limited number of studies have investigated the effect of dietary antioxidant-rich food including grapes on eye health in older adults. Objectives: To assess the effects on macular pigment accumulation of regular consumption of grapes in Singapore older adults. Methods: This was a 16 week, double-blind, randomized, placebo-controlled trial. Thirty-four Singapore older adults were randomized into regularly consuming either 46 g day-1 of freeze-dried table grape powder (the intervention group) or the same amount of placebo powder (the control group). Macular pigment optical density (MPOD), skin carotenoid status, advanced glycation end product (AGEs) status and dietary lutein intake were assessed every 4 weeks, and plasma lutein concentration, total antioxidant capacity and total phenolic content were measured every 8 weeks. Results: A significant time effect (p = 0.007) was observed for MPOD, and this is largely attributed to the improvement in the MPOD for the intervention group, as a significant increase was observed only in this group (week 0: 0.56 ± 0.04 D.U.; week 16: 0.61 ± 0.04 D.U., p < 0.01). Additionally, a significant increase in plasma total antioxidant capacity (week 0: 0.26 ± 0.13 mM TEAC; week 16: 0.36 ± 0.20 mM TEAC, p < 0.01) and total phenolic content (week 0: 10.50 ± 0.44 mg L-1 GAE; week 16: 12.58 ± 0.55 mg L-1 GAE, p < 0.001) was observed for the intervention group only. In contrast, a significant increase in skin AGE status was observed in the control group (week 0: 2.47 ± 0.24; week 16: 2.99 ± 0.12, p < 0.05) while this was mitigated in the intervention group. There were no differences in dietary lutein intake, plasma lutein concentration and skin carotenoid status between groups throughout the study. Conclusions: Regular intake of grapes may improve eye health in Singapore older adults, specifically in augmenting MPOD, which can be explained by an increase in plasma total antioxidant capacity and phenolic content, and the downregulation of AGEs. This study was registered at clinicatrials.gov as NCT05064865.

Pharmacotherapy and Nutritional Supplements for Neovascular Eye Diseases

In this review, we aim to provide an overview of the recent findings about the treatment of neovascular retinal diseases. The use of conventional drugs and nutraceuticals endowed with antioxidant and anti-inflammatory properties that may support conventional therapies will be considered, with the final aim of achieving risk reduction (prevention) and outcome improvement (cooperation between treatments) of such sight-threatening proliferative retinopathies. For this purpose, we consider a medicinal product one that contains well-defined compound(s) with proven pharmacological and therapeutic effects, usually given for the treatment of full-blown diseases. Rarely are prescription drugs given for preventive purposes. A dietary supplement refers to a compound (often an extract or a mixture) used in the prevention or co-adjuvant treatment of a given pathology. However, it must be kept in mind that drug-supplement interactions may exist and might affect the efficacy of certain drug treatments. Moreover, the distinction between medicinal products and dietary supplements is not always straightforward. For instance, melatonin is formulated as a medicinal product for the treatment of sleep and behavioral problems; at low doses (usually below 1 mg), it is considered a nutraceutical, while at higher doses, it is sold as a psychotropic drug. Despite their lower status with respect to drugs, increasing evidence supports the notion of the beneficial effects of dietary supplements on proliferative retinopathies, a major cause of vision loss in the elderly. Therefore, we believe that, on a patient-by-patient basis, the administration of nutraceuticals, either alone or in association, could benefit many patients, delaying the progression of their disease and likely improving the efficacy of pharmaceutical drugs.

Oxidative Stress and Antioxidants in Age-Related Macular Degeneration

Oxidative stress plays a crucial role in aging-related eye diseases, including age-related macular degeneration (AMD), cataracts, and glaucoma. With age, antioxidant reparative capacity decreases, and excess levels of reactive oxygen species produce oxidative damage in many ocular cell types underling age-related pathologies. In AMD, loss of central vision in the elderly is caused primarily by retinal pigment epithelium (RPE) dysfunction and degeneration and/or choroidal neovascularization that trigger malfunction and loss of photo-sensing photoreceptor cells. Along with various genetic and environmental factors that contribute to AMD, aging and age-related oxidative damage have critical involvement in AMD pathogenesis. To this end, dietary intake of antioxidants is a proven way to scavenge free radicals and to prevent or slow AMD progression. This review focuses on AMD and highlights the pathogenic role of oxidative stress in AMD from both clinical and experimental studies. The beneficial roles of antioxidants and dietary micronutrients in AMD are also summarized.

Antioxidant Nutraceutical Strategies in the Prevention of Oxidative Stress Related Eye Diseases

This review aims to discuss the delicate balance between the physiological production of reactive oxygen species and the role of antioxidant nutraceutical molecules in managing radicals in the complex anatomical structure of the eye. Many molecules and enzymes with reducing and antioxidant potential are present in different parts of the eye. Some of these, such as glutathione, N-acetylcysteine, α-lipoic acid, coenzyme Q10, and enzymatic antioxidants, are endogenously produced by the body. Others, such as plant-derived polyphenols and carotenoids, vitamins B2, C, and E, zinc and selenium, and omega-3 polyunsaturated fatty acids, must be obtained through the diet and are considered essential nutrients. When the equilibrium between the production of reactive oxygen species and their scavenging is disrupted, radical generation overwhelms the endogenous antioxidant arsenal, leading to oxidative stress-related eye disorders and aging. Therefore, the roles of antioxidants contained in dietary supplements in preventing oxidative stress-based ocular dysfunctions are also discussed. However, the results of studies investigating the efficacy of antioxidant supplementation have been mixed or inconclusive, indicating a need for future research to highlight the potential of antioxidant molecules and to develop new preventive nutritional strategies.

Potential roles of dietary zeaxanthin and lutein in macular health and function

Lutein, zeaxanthin, and meso-zeaxanthin are three xanthophyll carotenoid pigments that selectively concentrate in the center of the retina. Humans cannot synthesize lutein and zeaxanthin, so these compounds must be obtained from the diet or supplements, with meso-zeaxanthin being converted from lutein in the macula. Xanthophylls are major components of macular pigments that protect the retina through the provision of oxidant defense and filtering of blue light. The accumulation of these three xanthophylls in the central macula can be quantified with non-invasive methods, such as macular pigment optical density (MPOD). MPOD serves as a useful tool for assessing risk for, and progression of, age-related macular degeneration, the third leading cause of blindness worldwide. Dietary surveys suggest that the dietary intakes of lutein and zeaxanthin are decreasing. In addition to low dietary intake, pregnancy and lactation may compromise the lutein and zeaxanthin status of both the mother and infant. Lutein is found in modest amounts in some orange- and yellow-colored vegetables, yellow corn products, and in egg yolks, but rich sources of zeaxanthin are not commonly consumed. Goji berries contain the highest known levels of zeaxanthin of any food, and regular intake of these bright red berries may help protect against the development of age-related macular degeneration through an increase in MPOD. The purpose of this review is to summarize the protective function of macular xanthophylls in the eye, speculate on the compounds' role in maternal and infant health, suggest the establishment of recommended dietary values for lutein and zeaxanthin, and introduce goji berries as a rich food source of zeaxanthin.

Blue Light Exposure: Ocular Hazards and Prevention-A Narrative Review

INTRODUCTION

Exposure to blue light has seriously increased in our environment since the arrival of light emitting diodes (LEDs) and, in recent years, the proliferation of digital devices rich in blue light. This raises some questions about its potential deleterious effects on eye health. The aim of this narrative review is to provide an update on the ocular effects of blue light and to discuss the efficiency of methods of protection and prevention against potential blue light-induced ocular injury.

METHODS

The search of relevant English articles was conducted in PubMed, Medline, and Google Scholar databases until December 2022.

RESULTS

Blue light exposure provokes photochemical reactions in most eye tissues, in particular the cornea, the lens, and the retina. In vitro and in vivo studies have shown that certain exposures to blue light (depending on the wavelength or intensity) can cause temporary or permanent damage to some structures of the eye, especially the retina. However, currently, there is no evidence that screen use and LEDs in normal use are deleterious to the human retina. Regarding protection, there is currently no evidence of a beneficial effect of blue blocking lenses for the prevention of eye diseases, in particular age-related macular degeneration (AMD). In humans, macular pigments (composed of lutein and zeaxanthin) represent a natural protection by filtering blue light, and can be increased through increased intake from foods or food supplements. These nutrients are associated with lower risk for AMD and cataract. Antioxidants such as vitamins C, E, or zinc might also contribute to the prevention of photochemical ocular damage by preventing oxidative stress.

CONCLUSION

Currently, there is no evidence that LEDs in normal use at domestic intensity levels or in screen devices are retinotoxic to the human eye. However, the potential toxicity of long-term cumulative exposure and the dose-response effect are currently unknown.

Efficacy of lutein supplements on macular pigment optical density in highly myopic individuals: A randomized controlled trial

INTRODUCTION

Lutein supplementation is beneficial in preventing maculae from developing serious ocular diseases. This study aimed to evaluate the efficacy and safety of lutein administration in patients with high myopia (HM).

METHODS

In a single-center randomized double-blinded placebo-controlled trial conducted over 24 months, 22 eyes were enrolled in lutein and control groups. Among them, 15 eyes in the lutein group and 13 eyes in the control group completed the study. All patients with HM (axial length > 26.00) were administered lutein (20 mg) or placebo once daily for 6 months. The macular pigment optical density (MPOD), rate of change in MPOD, visual acuity, contrast sensitivity, and electroretinogram after administration were examined at baseline, 3 months, and 6 months.

RESULTS

The baseline MPOD in the control and lutein groups was 0.71 ± 0.21 and 0.70 ± 0.22, respectively. The MPOD in the control and lutein groups at 3 months was 0.70 ± 0.21 and 0.70 ± 0.25, respectively, and at 6 months was 0.66 ± 0.20 and 0.72 ± 0.27, respectively, which was not significantly different from those at baseline or between the groups. The MPOD significantly increased from baseline in the lutein group with less than 28.25 mm of axial length at 6 months (from 0.71 ± 0.20 to 0.78 ± 0.22, P = .02, t test). visual acuity, contrast sensitivity, and electroretinogram values were similar between the groups.

CONCLUSION

Lutein supplementation showed significant benefits in MPOD augmentation in patients with HM.

Nutraceuticals: A Promising Therapeutic Approach in Ophthalmology

Oxidative stress represents one of the main factors driving the pathophysiology of multiple ophthalmic conditions including presbyopia, cataracts, dry eye disease (DED), glaucoma, age-related macular degeneration (AMD) and diabetic retinopathy (DR). Currently, different studies have demonstrated the role of orally administered nutraceuticals in these diseases. For instance, they have demonstrated to improve lens accommodation in presbyopia, reduce protein aggregation in cataracts, ameliorate tear film stability, break up time, and tear production in dry eye, and participate in the avoidance of retinal neuronal damage and a decrease in intraocular pressure in glaucoma, contribute to the delayed progression of AMD, or in the prevention or treatment of neuronal death in diabetic retinopathy. In this review, we summarized the nutraceuticals which have presented a positive impact in ocular disorders, emphasizing the clinical assays. The characteristics of the different types of nutraceuticals are specified along with the nutraceutical concentration used to achieve a therapeutic outcome in ocular diseases.

What Advice Is Currently Given to Patients with Age-Related Macular Degeneration (AMD) by Eyecare Practitioners, and How Effective Is It at Bringing about a Change in Lifestyle? A Systematic Review

There is currently no treatment for early/intermediate Age-related Macular Degeneration (AMD) but Eye Care Professionals (ECPs) are recommended to advise patients about modifiable lifestyle factors, including dietary changes, that can slow disease progression. The aim of this review was to understand advice currently given to patients with AMD by ECPs and to evaluate evidence regarding patient compliance. A systematic review was conducted of literature published in electronic databases: CINAHL, MEDLINE, PsycINFO, PyscARTICLES, EMBASE, AMED. Methods followed PRISMA guidelines (PROSPERO registration number: CRD42020223724). Twenty-four reports were eligible for inclusion, 12 focused on ECP experience, 7 on patient experience, and 6 on impact of advice (one paper reported on the ECP and patient experience). Studies reported that a substantial proportion of patients did not recall receiving lifestyle modification advice from their ECP (57.95%, range 2-95% across patient based studies). Practitioners were most likely to provide advice about nutritional supplements (80%, range 67-93% across ECP studies), and least likely about smoking (44%, range 28-71% across ECP studies), however supplements advised did not always comply with evidence-based guidelines. The main reason for patients not following lifestyle advice was lack of provision by the ECP (54.5%, range 21-94% across studies on the impact of advice). The review highlighted a need for more studies to understand patient preferences for receiving advice and research on ECP perceived barriers to advice provision.

Review of Evidence for the Usage of Antioxidants for Eye Aging

Oxidative stress is one of the common factors leading to age-related eye diseases in older adults. Factors such as high oxygen consumption, high concentration of polyunsaturated fatty acids, and cumulative exposure to high-energy visible light in the eyes, lead to excessive generation of reactive oxygen species, hence triggering apoptosis of ocular cells and giving rise to ophthalmic diseases. Dietary supplements such as carotenoids, anthocyanins, and vitamins have antioxidant properties which may be of benefit in retaining better vision or reversing vision impairment; thus, studies have been conducted to understand the role of dietary supplements in the treatment or prevention of ophthalmic diseases. While high concentration of carotenoids such as lutein and zeaxanthin decrease the risk of developing age-related macular disease, anthocyanins and vitamins play a role in the treatment and prevention of other ophthalmic diseases: saffron extract reduced intraocular pressure in glaucoma patients; bilberry extract prevented impairments in lenses and retina, as well as alleviate symptoms of dry eye disease; high concentration of beta-carotene may reduce the risk of developing cataract. Further studies with clinical measurements are required to investigate the effectiveness of antioxidants on visual function and ophthalmic diseases.

Protective Effect of a Water-Soluble Carotenoid-Rich Extract of Cordyceps militaris against Light-Evoked Functional Vision Deterioration in Mice

Light-evoked retinal photodamage is considered an important factor contributing to functional vision deterioration and can even lead to light maculopathy or dry age-related macular degeneration. Loss of visual acuity (VA) and visual contrast sensitivity function (VCSF) are the major symptoms of retinal degenerative diseases. Cordyceps militaris is a carotenoid-rich Chinese medicinal fungus with antioxidant, anti-inflammatory, and immunomodulatory functions. C. militaris extract is a natural substance, and its bioactive constituents have been shown to confer health benefits, but their application in retinal tissue and functional vision protection in vivo remain incompletely understood. In the present study, we evaluated the influence of water-soluble, carotenoid-rich C. militaris extracts on the visual performance of light-damaged mouse retinas in vivo, using adult female CD-1^® (ICR) albino mice. We showed that oral administration of this C. militaris extract (10 mg/kg, twice daily) protected the neural retina tissue against light-evoked photoreceptor cell death, reduced Müller cell hypertrophic gliosis, and elevated GSH levels and promoted the recovery of VA- and VCSF-thresholds, especially for high spatial frequency-characterized vision. These results suggest that, probably because of its water-soluble carotenoids, C. militaris extract has the potential to prevent or treat light-induced visual dysfunction.

Macular pigment optical density and its determinants in a Russian population: the ural eye and medical study

PURPOSE

To assess the macular pigment optical density (MPOD) and its associations with ocular and systemic parameters and diseases.

METHODS

The population-based study Ural Eye and Medical Study included 5899 (80.5%) out of 7328 eligible individuals. As part of ophthalmological and systemic examinations, MPOD was measured by reflectometry.

RESULTS

Macular pigment optical density (MPOD) data were available for 4889 (82.9%) individuals (mean age:57.8 ± 10.1 years;range: 40-94). Mean values for MOPD, maximal MOPD, macular pigment (MP) area and MP volume were 0.13 ± 0.04 d.u. (density units), 0.36 ± 0.09 d.u., 60 791 ± 14 826 pixel and 8033 ± 2888 d.u.pixel, respectively. A higher MP density was correlated (regression coefficient r: 0.63) with older age (standardized regression coefficient beta: 0.59; non-standardized regression coefficient B: 0.23; 95% confidence interval (CI): 0.22, 0.23; p < 0.001), female sex (beta: 0.08; B:0.63; 95%CI: 0.44, 0.83; p < 0.001), rural region of habitation (beta: 0.13; B: 1.02; 95%CI: 0.83, 1.22; p < 0.001), lower body mass index (beta: -0.04; B: -0.03; 95%CI: -0.05, 0.01; p = 0.004), lower prevalence of chronic obstructive pulmonary disorder (beta: -0.03; B: -0.43; 95%CI: -0.79, -0.08; p = 0.02), higher erythrocyte sedimentation rate (beta: 0.03; B: 0.01; 95%CI: 0.002, 0.02; p = 0.03), lower leukocyte cell count (beta: -0.04; B: -0.10; 95%CI: -0.16, -0.03; p = 0.003), thinner temporal parafoveal retinal thickness (beta: -0.06; B: -0.01;95%CI: -0.01, -0.003; p < 0.001), thinner central corneal thickness (beta: -0.06; B: -0.006; 95%CI: -0.009, -0.004; p < 0.001), higher prevalence of pseudophakia (beta: 0.09;B:2.08; 95%CI: 1.50, 2.65; p < 0.001) and reticular pseudo drusen (RPD) (beta: 0.03; B: 0.56; 95%CI: 0.13, 0.98; p = 0.01) and lower stage of open-angle glaucoma (beta: -0.03; B: -0.39; 95%CI: -0.74, -0.04; p = 0. 03). Prevalence (p = 0.44; beta: -0.01) and degree (p = 0.70; beta: -0.01) of angle-closure glaucoma, prevalence (p = 0.31; beta: 0.01) of age-related macular degeneration (AMD) without RPD and prevalence (p = 0.95; beta: 0.001) of diabetic retinopathy were not significantly associated with the mean MP density in that model.

CONCLUSIONS

A higher RPD prevalence and lower stage of open-angle glaucoma were ophthalmological disorders associated with a higher MPOD in a multivariable analysis, including parameters of older age, pseudophakia, female sex, rural region, lower body mass index and lower perifoveal retinal thickness.

Lutein and Zeaxanthin and Their Roles in Age-Related Macular Degeneration-Neurodegenerative Disease

Lutein and zeaxanthin belong to the xanthophyll family of carotenoids, which are pigments produced by plants. Structurally, they are very similar, differing only slightly in the arrangement of atoms. Key sources of these carotenoids include kale, savoy cabbage, spinach, broccoli, peas, parsley, corn, and egg yolks. The recommended daily intake of lutein is approximately 10.0 mg and that of zeaxanthin is 2 mg. Lutein intake in adults varies, with average intakes being 1-2 mg/day. Due to the lack of synthesis of consumption of these compounds in humans, these substances are extremely important for the proper functioning of certain organs of the body (eye, skin, heart, intestines). Eating a lot of dark leafy vegetables and some fruits can help to prevent our bodies from developing diseases. The protective effects of carotenoids are mainly related to their defense against oxidative stress and their ability to scavenge free radicals. Lutein and zeaxanthin are the only dietary carotenoids that accumulate in the retina, specifically the macula, and are called macular pigments. These carotenoids are concentrated by the action of specific binding proteins such as StARD3, which binds lutein, and GSTP1, which binds zeaxanthin and its dietary metabolite, mesozeaxanthin. It has been shown that supportive therapy with lutein and zeaxanthin can have a beneficial effect in delaying the progression of eye diseases such as age-related macular degeneration (AMD) and cataracts. This article presents the current state of knowledge on the role of lutein and zeaxanthin, especially from human studies targeting their metabolism and bioavailability, with recommendations to consume xanthophyll-rich foods.

Reply to the 'Comment on "The association between carotenoids and subjects with overweight or obesity: a systematic review and meta-analysis"' by N. Shokri-mashhadi and S. Saadat, Food Funct., 2021, 12, DOI: 10.1039/D1FO01617B

Here, we re-emphasize the purpose of our meta-analysis of the associations between carotenoids and subjects with excess body weight (Yao et al., 2021) and address some of the points raised in the commentary by Nafiseh Shokri-mashhadi and Saeed Saadat. The commentary focused on the methodological faults of our published meta-analysis research-but the research was rigorously conducted and scientifically sound, following strictly the relevant requirements of the Cochrane guidelines. Therefore, in the current reply, we included an elaboration and thorough discussion of the search strategy, inclusion and exclusion criteria, and tests of heterogeneity for the discussed meta-analysis in light of the comments made in the commentary. In conclusion, we believe that our study has made an essential contribution to the investigation of the significance of carotenoids in people with excess body weight.

Assessment of Maternal Macular Pigment Optical Density (MPOD) as a Potential Marker for Dietary Carotenoid Intake during Lactation in Humans

Pregnancy and lactation can change the maternal nutrient reserve. Non-invasive, quantitative markers of maternal nutrient intake could enable personalized dietary recommendations that improve health outcomes in mothers and infants. Macular pigment optical density (MPOD) is a candidate marker, as MPOD values generally reflect carotenoid intake. We evaluated the association of MPOD with dietary and breastmilk carotenoids in postpartum women. MPOD measurements and dietary intake of five carotenoids were obtained from 80 mothers in the first three months postpartum. Breastmilk samples from a subset of mothers were analyzed to determine their nutrient composition. The association between MPOD and dietary or breastmilk carotenoids was quantitatively assessed to better understand the availability and mobilization of carotenoids. Our results showed that dietary α-carotene was positively correlated with MPOD. Of the breastmilk carotenoids, 13-cis-lutein and trans-lutein were correlated with MPOD when controlled for the total lutein in breastmilk. Other carotenoids in breastmilk were not associated with MPOD. Maternal MPOD is positively correlated with dietary intake of α-carotene in the early postpartum period, as well as with the breastmilk content of lutein. MPOD may serve as a potential marker for the intake of carotenoids, especially α-carotene, in mothers in the early postpartum period.

Goji Berry Intake Increases Macular Pigment Optical Density in Healthy Adults: A Randomized Pilot Trial

Age-related macular degeneration (AMD) is the third leading cause of blindness worldwide. Macular pigment optical density (MPOD), a biomarker for AMD, is a non-invasive measure to assess risk. The macula xanthophyll pigments lutein (L) and zeaxanthin (Z) protect against blue light and provide oxidant defense, which can be indexed by MPOD. This study examined the effects of Z-rich goji berry intake on MPOD and skin carotenoids in healthy individuals. A randomized, unmasked, parallel-arm study was conducted with 27 participants, aged 45–65, who consumed either 28 g of goji berries or a supplement containing 6 mg L and 4 mg Z (LZ), five times weekly for 90 days. After 90 days, MPOD was significantly increased in the goji berry group at 0.25 and 1.75 retinal eccentricities (p = 0.029 and p = 0.044, respectively), while no changes were noted in the LZ group. Skin carotenoids were significantly increased in the goji berry group at day 45 (p = 0.025) and day 90 (p = 0.006), but not in the LZ group. Regular intake of goji berries in a healthy middle-aged population increases MPOD may help prevent or delay the development of AMD.

Changes in Lutein Status Markers (Serum and Faecal Concentrations, Macular Pigment) in Response to a Lutein-Rich Fruit or Vegetable (Three Pieces/Day) Dietary Intervention in Normolipemic Subjects

Lutein is mainly supplied by dietary fruit and vegetables, and they are commonly jointly assessed in observational and interventional studies. Lutein bioavailability and health benefits depend on the food matrix. This study aimed to assess the effect of dietary intervention with lutein-rich fruit or vegetables on lutein status markers, including serum and faecal concentrations (by high pressure liquid chromatography), dietary intake (24 h recalls ×3), and macular pigment optical density (MPOD) and contrast threshold (CT) as visual outcomes. Twenty-nine healthy normolipemic subjects, aged 45–65 y, consumed 1.8 mg lutein/day supplied from fruits (14 subjects, 500 g/day of oranges, kiwi and avocados) or vegetables (15 subjects, 180 g/day of green beans, pumpkin, and sweet corn) for four weeks. Serum lutein concentration increased by 37%. The effect of the food group intervention was statistically significant for serum lutein+zeaxanthin concentration (p = 0.049). Serum α- and β-carotene were influenced by food type (p = 0.008 and p = 0.005, respectively), but not by time. Serum lutein/HDL-cholesterol level increased by 29% (total sample, p = 0.008). Lutein+zeaxanthin/HDL-cholesterol increased, and the intervention time and food group eaten had an effect (p = 0.024 and p = 0.010, respectively) which was higher in the vegetable group. The MPOD did not show variations, nor did it correlate with CT. According to correlation matrixes, serum lutein was mainly related to lutein+zeaxanthin expressed in relation to lipids, and MPOD with the vegetable group. In faecal samples, only lutein levels increased (p = 0.012). This study shows that a relatively low amount of lutein, supplied by fruit or vegetables, can have different responses in correlated status markers, and that a longer intervention period is needed to increase the MPOD. Therefore, further study with larger sample sizes is needed on the different responses in the lutein status markers and on food types and consumption patterns in the diet, and when lutein in a “pharmacological dose” is not taken to reduce a specific risk.

Nutrition knowledge and dietary patterns in ophthalmic patients

CLINICAL SIGNIFICANCE

Ophthalmic nutrition education programs and good dietary patterns are of considerable significance to ocular health outcomes.

BACKGROUND

The study aimed at assessing the level of ophthalmic nutrition knowledge and to compare the dietary patterns between different ophthalmic patients.

METHODS

Four hundred and ninety-two adults (mean age 54.7 ± 19.4-years) receiving care at three eye-care facilities in Ghana were surveyed: 171 had senile cataract, 162 had open-angle glaucoma, and 159 had healthy eyes. A modified food frequency questionnaire was administered to elicit ophthalmic nutrition knowledge and dietary intake information of participants over the last 30-days. The results were compared between the three groups.

RESULTS

More than half of the participants (n = 267; 54.3 per cent) had received some form of education on food sources that are good for the eyes and vision, with healthy participants accounting for 50.6 per cent of this proportion. Television (55.1 per cent; 147/267), radio (49.1 per cent; 131/267) and the eye doctor (34.1 per cent; 91/267) were the most frequent sources of ophthalmic nutritional knowledge. Overall, less than one-quarter of the participants (n = 108; 22.2 per cent) were able to correctly identify one food source for at least four out of seven selected ophthalmic nutrients. Vitamin C was the most frequently consumed ophthalmic nutrient, whereas lycopene was the least taken across all groups. The average ophthalmic nutrients intake score for those with healthy eyes (59.16 [53.39-64.93]) was significantly greater than for both glaucoma patients (37.73 [32.01-43.44]) and cataract patients (34.81 [29.24-40.37]).

CONCLUSION

In addition to poor ophthalmic nutrition awareness and knowledge, both cataract and glaucoma patients, compared to those with healthy eyes, consumed a lesser amount of nutrients considered vital for eye health and vision. Ophthalmic nutrition education is needed to improve eye-health outcomes.

The ALGOVUE Clinical Trial: Effects of the Daily Consumption of Eggs Enriched with Lutein and Docosahexaenoic Acid on Plasma Composition and Macular Pigment Optical Density

Background. Carotenoids and docosahexaenoic acid (DHA) were identified as essential components for eye health and are both naturally present in eggs. Objective. We aimed to evaluate the effect of the daily consumption of two eggs enriched with lutein/zeaxanthin and DHA on macular pigment optical density (MPOD) and on circulating xanthophyll and fatty acid concentrations in healthy participants. Methods. Ninety-nine healthy volunteers consumed either two standard eggs or two enriched eggs per day for 4 months. MPOD was measured at baseline (V0) and at follow-up (V4) using a modified confocal scanning laser ophthalmoscope (primary outcome). Blood samples were collected to determine total plasma and lipoprotein fatty acids and lutein/zeaxanthin compositions at V0 and V4 (secondary outcomes). Results. A slight but significant increase in MPOD was observed for all study participants consuming two eggs per day for 4 months at all eccentricities (0.5°, 1°, 2°, and 4°). Plasma and lipoprotein lutein, zeaxanthin, and DHA concentrations significantly increased in both groups but were greater in the enriched group (for the enriched group (V0 vs. V4): lutein, 167 vs. 369 ng/mL; zeaxanthin, 17.7 vs. 29.2 ng/mL; DHA, 1.89 vs. 2.56% of total fatty acids). Interestingly, lutein from high-density lipoprotein (HDL) was strongly correlated with MPOD at 0.5 and 1° eccentricities (rho = 0.385, p = 0.008, and rho = 0.461, p = 0.001, respectively). Conclusions. MPOD was slightly increased in both groups. Lutein, zeaxanthin, and DHA plasma concentrations were strongly enhanced in the enriched group compared with the standard group. A significant correlation was found between MPOD level and lutein concentration in HDL.

Macular Pigment Response to Lutein, Zeaxanthin, and Meso-zeaxanthin Supplementation in Open-Angle Glaucoma

Purpose

To evaluate macular pigment response to carotenoid supplementation in glaucomatous eyes.

Design

Double-masked, randomized, placebo-controlled clinical trial, the European Nutrition in Glaucoma Management Study (ClinicalTrials.gov identifier, NCT04460365).

Participants

Sixty-two participants (38 men, 24 women) with a diagnosis of open-angle glaucoma were enrolled. Forty-two were randomized to receive the active supplement, 20 participants were allocated to placebo.

Methods

Macular pigment optical density (MPOD) was measured by autofluorescence using the Heidelberg Spectralis scanning laser ophthalmoscope. Macular pigment optical density volume within the central 6° of retinal eccentricity as well as MPOD at 0.23°, 0.51°, 0.74°, and 1.02° were recorded at baseline and at 6-month intervals over 18 months. Visual function was assessed using visual acuity, mesopic and photopic contrast sensitivity under glare conditions, photo stress recovery time, microperimetry, and Glaucoma Activities Limitation 9 questionnaire. Advanced glaucoma module scans of retinal nerve fiber layer thickness and ganglion cell complex thickness over the central 6° of retinal eccentricity also were completed at each study visit.

Main Outcome Measures

Change in MPOD after supplementation with 10 mg lutein, 2 mg zeaxanthin, and 10 mg meso-zeaxanthin or placebo over 18 months.

Results

A mixed-model repeated measures analysis of variance revealed a statistically significant increase in MPOD volume (significant time effect: F(3,111) = 89.31, mean square error (MSE) = 1656.9; P < 0.01). Post hoc t tests revealed a significant difference in MPOD volume at each study visit for the treatment group (P < 0.01 for all), but no change in the placebo group (P > 0.05 for all). A statistically significant increase in mesopic contrast sensitivity under glare conditions was noted at 18 months in the treatment group, but not placebo. No other structural or functional changes were observed. No serious adverse events were noted during the trial.

Conclusions

Macular pigment can be augmented in glaucomatous eyes by supplementation with a formulation containing the carotenoids lutein, zeaxanthin, and meso-zeaxanthin. The greatest relative benefit was observed in those with the lowest baseline levels, but increases were noted across all participants and each retinal eccentricity. The potential benefits of MP augmentation for macular health in glaucoma merit further long-term evaluation.

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.

A Systematic Review of Carotenoids in the Management of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) remains a leading cause of modifiable vision loss in older adults. Chronic oxidative injury and compromised antioxidant defenses represent essential drivers in the development of retinal neurodegeneration. Overwhelming free radical species formation results in mitochondrial dysfunction, as well as cellular and metabolic imbalance, which becomes exacerbated with increasing age. Thus, the depletion of systemic antioxidant capacity further proliferates oxidative stress in AMD-affected eyes, resulting in loss of photoreceptors, neuroinflammation, and ultimately atrophy within the retinal tissue. The aim of this systematic review is to examine the neuroprotective potential of the xanthophyll carotenoids lutein, zeaxanthin, and meso-zeaxanthin on retinal neurodegeneration for the purpose of adjunctive nutraceutical strategy in the management of AMD. A comprehensive literature review was performed to retrieve 55 eligible publications, using four database searches from PubMed, Embase, Cochrane Library, and the Web of Science. Epidemiology studies indicated an enhanced risk reduction against late AMD with greater dietary consumption of carotenoids, meanwhile greater concentrations in macular pigment demonstrated significant improvements in visual function among AMD patients. Collectively, evidence strongly suggests that carotenoid vitamin therapies offer remarkable synergic protection in the neurosensory retina, with the potential to serve as adjunctive nutraceutical therapy in the management of established AMD, albeit these benefits may vary among different stages of disease.

An appraisal of trials investigating the effects on macular pigment optical density of lutein and zeaxanthin dietary interventions: a narrative review

Lutein and zeaxanthin (L/Z), xanthophylls obtained from the diet, are deposited in the macula of the eye. The macular concentration of L/Z is quantifiable as macular pigment optical density (MPOD). The aim of this review was to critically appraise the effect on MPOD of increasing L/Z intake by dietary intervention in adults. Pubmed, Cochrane Library, Web of Science, and Cinahl were searched up to April 2020. Ten studies investigating populations with and without age-related macular degeneration were included. MPOD increased significantly in 2 of the 8 controlled studies. Studies varied largely in the prescribed dietary L/Z dosage, duration, and participant characteristics. No relationships between types of dietary L/Z interventions and MPOD response could be determined. Limited monitoring of habitual dietary L/Z intake was identified as a major limitation of all 10 studies. Habitual dietary L/Z intake should be closely monitored in future studies to account for their effects on MPOD response to dietary L/Z interventions.

[Involvement of egg antioxidant components in macular protection and vision improvement]

Age-related macular degeneration (AMD) is an ocular pathology that occurs with excess free radicals, which damages the photoreceptors of the retina producing a disability in the pigment epithelium, which leads, in the most advanced cases, to severe and irreversible vision loss. Lutein and zeaxanthin (L & Z) intake, which are abundant pigments in the macula and have antioxidant and anti-inflammatory action, as well as a role as blue light filter, seem to have a positive effect on the prevention of AMD. These carotenoids cannot be synthesized in the body and must be ingested with the diet. Green leafy vegetables and eggs are the main sources. The former have a higher L & Z content than the latter, but their bioavailability is lower, due to the lipid matrix of the egg yolk, which improves absorption. In relation to the consumption of eggs and AMD prevention, short-term consumption has been associated with an increase in serum concentrations of L & Z, long-term consumption with an increase in the density of macular pigment, and very long- term consumption with a decrease in the risk of developing advanced and neovascular AMD. These facts highlight the advantages of consuming eggs, which should be incorporated into the usual diet in order to minimize the progression of this ocular disease.

The Effect of Lutein/Zeaxanthin Intake on Human Macular Pigment Optical Density: A Systematic Review and Meta-Analysis

Lutein, zeaxanthin, and meso-zeaxanthin are the only carotenoids found in the human macula and may have a role in visual function. These carotenoids are reported to protect the retina, and thus vision, as antioxidants and by acting as a blue light filter. Our objective was to determine a minimum concentration of lutein/zeaxanthin intake that is associated with a statistically significant and/or clinically important change in macular pigment optical density (MPOD) among adults with healthy eyes. We searched Ovid MEDLINE, CENTRAL, and the Commonwealth of Agriculture Bureau for English-language studies through to July 2020. Two reviewers screened results to identify studies that evaluated supplements or dietary sources of lutein/zeaxanthin on MPOD among adults with healthy eyes. One reviewer extracted data and assessed strength of evidence, which was confirmed by a second reviewer. Two independent reviewers assessed the risk of bias. Meta-analyses were stratified by total lutein/zeaxanthin dose. We included 46 studies (N = 3189 participants; mean age = 43 y; 42% male). There was no statistically significant change in MPOD among studies evaluating <5 mg/d of total lutein/zeaxanthin intake which primarily assessed dietary interventions for 3-6 mo (pooled mean difference, 0.02; 95% CI: -0.01 to 0.05). The pooled mean increase in MPOD was 0.04 units (95% CI: 0.02 to 0.07) among studies evaluating 5 to <20 mg/d of lutein/zeaxanthin and was 0.11 units (95% CI: 0.06 to 0.16) among studies evaluating ≥20 mg/d of lutein/zeaxanthin for 3-12 mo. MPOD increased with lutein/zeaxanthin intake, particularly at higher doses, among adults with healthy eyes. The effects of lutein/zeaxanthin intake at doses <5 mg/d or from dietary sources is less clear. Increased lutein/zeaxanthin intake can help with maintaining ocular health. Future research is needed to determine the minimum dose and duration of lutein/zeaxanthin intake that is associated with a clinically important change in MPOD or visual function.

Plasma Lutein, a Nutritional Biomarker for Development of Advanced Age-Related Macular Degeneration: The Alienor Study

Lutein and zeaxanthin may lower the risk of age-related macular degeneration (AMD). We evaluated the associations of plasma lutein and zeaxanthin with the incidence of advanced AMD in the Alienor study (Antioxydants Lipides Essentiels Nutrition et Maladies Oculaires). Alienor study is a prospective population-based cohort of 963 residents of Bordeaux, France, who were 73 years or older at baseline (2006-2008). The present study included 609 participants with complete ophthalmologic and plasma carotenoids data. Examinations were performed every two years over an eight-year period (2006 to 2017). Plasma lutein and zeaxanthin were determined at baseline from fasting blood samples using high-performance liquid chromatography. Cox proportional hazard models were used to assess associations between plasma lutein, zeaxanthin, and their (total cholesterol (TC) + triglycerides (TG)) ratios with AMD. Among the 609 included participants, 54 developed advanced incident AMD during a median follow-up time of 7.6 years (range 0.7 to 10.4). Participants with higher plasma lutein had a reduced risk for incident advanced AMD in the fully adjusted model (HR = 0.63 per 1-SD increase (95% CI, 0.41-0.97), p = 0.03). A similar association was observed using the lutein/(TC + TG) ratio (HR = 0.59 (95% CI, 0.39-0.90), p = 0.01). No associations were evidenced for other carotenoids. Higher plasma lutein was associated with a 37% reduced risk of incident advanced AMD.

Carotenoids in the Management of Glaucoma: A Systematic Review of the Evidence

Primary open-angle glaucoma (POAG) remains a leading cause of irreversible blindness globally. Recent evidence further substantiates sustained oxidative stress, and compromised antioxidant defenses are key drivers in the onset of glaucomatous neurodegeneration. Overwhelming oxidative injury is likely attributed to compounding mitochondrial dysfunction that worsens with age-related processes, causing aberrant formation of free radical species. Thus, a compromised systemic antioxidant capacity exacerbates further oxidative insult in glaucoma, leading to apoptosis, neuroinflammation, and subsequent tissue injury. The purpose of this systematic review is to investigate the neuroprotective benefits of the macular carotenoids lutein, zeaxanthin, and meso-zeaxanthin on glaucomatous neurodegeneration for the purpose of adjunctive nutraceutical treatment in glaucoma. A comprehensive literature search was conducted in three databases (PubMed, Cochrane Library, and Web of Science) and 20 records were identified for screening. Lutein demonstrated enhanced neuroprotection on retinal ganglion cell survival and preserved synaptic activity. In clinical studies, a protective trend was seen with greater dietary consumption of carotenoids and risk of glaucoma, while greater carotenoid levels in macular pigment were largely associated with improved visual performance in glaucomatous eyes. The data suggest that carotenoid vitamin therapy exerts synergic neuroprotective benefits and has the capacity to serve adjunctive therapy in the management of glaucoma.

From carotenoid intake to carotenoid blood and tissue concentrations - implications for dietary intake recommendations

There is uncertainty regarding carotenoid intake recommendations, because positive and negative health effects have been found or are correlated with carotenoid intake and tissue levels (including blood, adipose tissue, and the macula), depending on the type of study (epidemiological vs intervention), the dose (physiological vs supraphysiological) and the matrix (foods vs supplements, isolated or used in combination). All these factors, combined with interindividual response variations (eg, depending on age, sex, disease state, genetic makeup), make the relationship between carotenoid intake and their blood/tissue concentrations often unclear and highly variable. Although blood total carotenoid concentrations <1000 nmol/L have been related to increased chronic disease risk, no dietary reference intakes (DRIs) exist. Although high total plasma/serum carotenoid concentrations of up to 7500 nmol/L are achievable after supplementation, a plateauing effect for higher doses and prolonged intake is apparent. In this review and position paper, the current knowledge on carotenoids in serum/plasma and tissues and their relationship to dietary intake and health status is summarized with the aim of proposing suggestions for a "normal," safe, and desirable range of concentrations that presumably are beneficial for health. Existing recommendations are likewise evaluated and practical dietary suggestions are included.

Biofortified orange corn increases xanthophyll density and yolk pigmentation in egg yolks from laying hens

Plant breeding has developed corn genotypes with grain higher in levels of carotenoids. Dietary consumption of specific carotenoids by humans has been associated with improved eye health, notably with some protection against age-related macular degeneration. Increasing dietary sources of macular carotenoids in the standard American diet might be accomplished by using high carotenoid Orange Corn in poultry diets to increase macular carotenoid concentrations in egg yolks. Three hundred sixty laying hens (Novogen White) were fed three different diets over 31 days. Each diet had six replicates of 20 hens housed in enrichable colony cages. The only difference was the type of corn included - white, yellow, and orange, in order to assess the impact of each type of corn on egg production, yolk pigmentation, and carotenoid deposition. This study assessed yolk color and carotenoid densities using a portable colorimeter and the DSM YolkFan, and by high performance liquid chromatography (HPLC) on eggs from the feeding study and on 43 cartons of 12 eggs commercially available and produced in various production settings: conventional cage, cage-free, cage-free organic, free-range/pasture, and free-range/pasture organic. Yolks from hens fed with the Orange Corn diet produced eggs with higher (P < 0.01) DSM yolk color (6 to 10) and total xanthophylls (23.5 to 35.3 μg/g of egg yolk) compared to the yellow diet (5 to 6 DSM and 12.3 to 17.7 μg/g xanthophylls) and white diet (1 to 2 DSM and 2.5 to 3.0 μg/g xanthophylls). Egg yolks reached a maximum xanthophyll accumulation with the Orange Corn diet (35.3 μg/g of egg yolk) after twelve days of treatment and maintained steady levels at subsequent time points. In general, xanthophyll levels in yolks from the Orange Corn diet were superior (30–61% higher) to any of the commercial egg brands, suggesting that feeding high carotenoid Orange Corn increases xanthophyll density in eggs.

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.

Dietary Intake of Carotenoid-Rich Vegetables Reduces Visceral Adiposity in Obese Japanese men-A Randomized, Double-Blind Trial

Metabolic syndrome, whose main diagnostic component is obesity, is a risk factor for lifestyle-related diseases, type 2 diabetes, and cardiovascular disease. Diet is known to affect the prevalence of metabolic syndrome. However, the effect of diet on metabolic syndrome in Japanese subjects has not been thoroughly explored. In the present study, we investigated the effect of carotenoid-rich vegetables, particularly lycopene- and lutein-rich vegetables, on the metabolic syndrome in obese Japanese men. We conducted an 8-week long randomized, double-blinded, controlled clinical trial in which, 28 middle-aged (40 ≤ age < 65) Japanese men with high body mass index (BMI ≥ 25) were randomized into four dietary groups: high lycopene + high lutein (HLyHLu), high lycopene + low lutein (HLyLLu), low lycopene + high lutein (LLyHLu), and low lycopene + low lutein (LLyLLu). Our results showed that daily beverage-intake increased the plasma levels of carotenoids without adverse effects, and the visceral fat level was significantly decreased in all the groups. The waist circumference was significantly decreased only in the HLyLLu group, whereas the CoQ10 oxidation rate was decreased in all the groups. The gene expression profiles of whole blood samples before and after ingestion differed only in the LLyLLu group, indicating the effect of carotenoids on gene expression profile. In conclusion, our results suggest that dietary uptake of carotenoid-rich vegetables increases their concentration in blood and reduces the intra-abdominal visceral fat.

Feasibility study of a docosahexaenoic acid optimized nutraceutical formulation on the macular levels of lutein in a healthy Mediterranean population

INTRODUCTION

Macular pigment optical density plays a pivotal role in maintaining macular structure and functioning. Research shows that daily consumption of lutein reduces the risk of eye diseases such as age-related macular degeneration.

OBJECTIVE

This study analyzes the influence of a supplementation containing lutein and antioxidant vitamins either with or without docosahexaenoic acid (DHA), with the main objective of identifying macular pigment optical density (MPOD) changes in both eyes at the end of the follow-up using the Visucam® retinograph. The secondary endpoint was to determine variation in the lutein and DHA levels in plasma and red blood cell membranes respectively.

METHODS

One hundred healthy participants (200 eyes) aged 40-70 years (mean age 49.3 years, SEM=13.7) were randomized in a 1:1 ratio to receive daily one of the following supplements for 3 months: Lutein group (LT-G, n=49), Lutein /Docosahexaenoic acid group (LT/DHA-G, n= 51). The MPOD was measured at baseline and end of the follow-up by retinography (Visucam® retinograph). Lutein in plasma was determined by HPLC and DHA in red blood cell membranes was analyzed by gas chromatograph/mass spectrometer.

RESULTS

From baseline, macular pigment optical density showed significantly higher values in the Lutein/DHA group than in the Lutein group at the end of the study (p<0.0001). Significantly higher Lutein in plasma (p<0.0001) and DHA (p<0.0001) levels in the red blood cell membrane were seen in the Lutein/DHA group than in the Lutein group at the 3-month follow-up.

CONCLUSION

Lutein supplementation improves macular pigment optical density in healthy subjects from a Mediterranean population being significantly increased in the presence of DHA. Therefore, our findings highlight the relevance of the adjunctive role of DHA for a better Lutein availability.

Why is Zeaxanthin the Most Concentrated Xanthophyll in the Central Fovea?

Diet-based xanthophylls (zeaxanthin and lutein) are conditionally essential polar carotenoids preferentially accreted in high concentrations (1 mM) to the central retina, where they have the capacity to impart unique physiologically significant biophysical biochemical properties implicated in cell function, rescue, and survival. Macular xanthophylls interact with membrane-bound proteins and lipids to absorb/attenuate light energy, modulate oxidative stress and redox balance, and influence signal transduction cascades implicated in the pathophysiology of age-related macular degeneration. There is exclusive transport, sequestration, and appreciable bioamplification of macular xanthophylls from the circulating carotenoid pool to the retina and within the retina to regions required for high-resolution sensory processing. The distribution of diet-based macular xanthophylls and the lutein metabolite meso-zeaxanthin varies considerably by retinal eccentricity. Zeaxanthin concentrations are 2.5-fold higher than lutein in the cone-dense central fovea. This is an ~20-fold increase in the molar ratio relative to eccentric retinal regions with biochemically detectable macular xanthophylls. In this review, we discuss how the differences in the specific properties of lutein and zeaxanthin could help explain the preferential accumulation of zeaxanthin in the most vulnerable region of the macula.

Comparison of Macular Pigment Optical Density in Glaucoma Patients and Healthy Subjects - A Prospective Diagnostic Study

Purpose

To evaluate the relationship between macular pigment optical density (MPOD) and glaucoma.

Methods

Forty-three patients with an established glaucoma diagnosis (25 females, 18 males, mean age 70 (range 34–84)) and 43 healthy controls (28 females, 15 males, mean age 62 (range 30–87)) were included in this prospective diagnostic case-control study. All subjects underwent detailed eye examination including ophthalmoscopy, best-corrected visual acuity, biomicroscopy, measurement of the axial length of the eye, objective refraction, lens status, central foveal thickness on spectral-domain optical coherence tomography (SD-OCT). In all glaucoma patients, a visual field assessment and a measurement of the retinal nerve fibre layer (RNFL) on SD-OCT were done. MPOD was determined using the macula pigment module of the Spectralis HRA+OCT (Heidelberg Engineering GmbH, Heidelberg, Germany) at 0.51°, 1.02° and 1.99° retinal eccentricity using two-wavelength autofluorescence imaging.

Results

In the glaucoma group, the median of the visual field mean defect was 5.1 db (quartiles 3.0 and 13.5) and the mean RNFL-thickness global was 65.9 µm (SD ± 16.1). Median MPOD measured at 0.51°, 1.02° and 1.99° retinal eccentricity in the glaucoma group was 0.42 DU, 0.34 DU and 0.13 DU, in the control group 0.40 DU, 0.35 DU and 0.12 DU respectively. There was no statistically significant difference of median MPOD between glaucomatous and control eyes (p=0.510, 0.735, 0.481). No significant relation between MPOD at 1.02 retinal eccentricity and the presence of glare symptoms was found (p=0.948). However, age seems to correlate with median MPOD measured at 1.02 retinal eccentricity (p=0.017).

Conclusion

There was no evidence for lower MPOD levels in our glaucoma patients; lower MPOD was not related to the presence of glare symptoms. However there seems to be a positive correlation between age and MPOD at 1.02° retinal eccentricity. To further investigate the relation between glare reported by glaucoma patients and glare disability linked to lower MPOD levels, additional studies are necessary that include both detailed inquiry of the quality of glare and a glare quantification and precise analysis of MPOD levels in glaucoma patients.

A Novel Botanical Combination Attenuates Light-Induced Retinal Damage through Antioxidant and Prosurvival Mechanisms

The prevalence of light-induced eye fatigue is increasing globally. Efficient regimen for mitigating light-induced retinal damage is becoming a compelling need for modern society. We investigated the effects of a novel combination of lutein ester, zeaxanthin, chrysanthemum, goji berry, and black currant extracts against retinal damage. In the current work, both in vitro and in vivo light-induced retinal damage models were employed. Animal study showed that under strong light exposure (15000 lx for 2 hours), the a-wave and b-wave from electroretinogram were significantly decreased. Treatment with the combination significantly restored the decrease for b-wave under high- and low-stimulus intensity. Histological analysis reported a substantial decrease in the outer nuclear layer (ONL) thickness in the model group, while the supplementation with the combination significantly improved the ONL thickness. To further explore the underlying mechanism of the protective effects, we utilized ARPE-19 retinal pigment epithelial cell line and found that strong light stimulation (2900 lx for 30 minutes) significantly increased phosphorylation of p38 and JNK and decreased HIF expression. Intriguingly, chrysanthemum, black currant extracts, lutein ester, and zeaxanthin significantly decreased the phosphorylation of p38 and JNK, while chrysanthemum, goji berry, black currant extracts, and lutein ester restored HIF expression. The botanical combination can alleviate light-induced retina damage, potentially through antioxidant and prosurvival mechanisms.

Risk factors for progression of age-related macular degeneration

Purpose

Age‐related macular degeneration (AMD) is a degenerative disease of the macula, often leading to progressive vision loss. The rate of disease progression can vary among individuals and has been associated with multiple risk factors. In this review, we provide an overview of the current literature investigating phenotypic, demographic, environmental, genetic, and molecular risk factors, and propose the most consistently identified risk factors for disease progression in AMD based on these studies. Finally, we describe the potential use of these risk factors for personalised healthcare.

Recent findings

While phenotypic risk factors such as drusen and pigment abnormalities become more important to predict disease progression during the course of the disease, demographic, environmental, genetic and molecular risk factors are more valuable at earlier disease stages. Demographic and environmental risk factors such as age and smoking are consistently reported to be related to disease progression, while other factors such as sex, body mass index (BMI) and education are less often associated. Of all known AMD variants, variants that are most consistently reported with disease progression are rs10922109 and rs570618 in CFH, rs116503776 in C2/CFB/SKIV2L, rs3750846 in ARMS2/HTRA1 and rs2230199 in C3. However, it seems likely that other AMD variants also contribute to disease progression but to a lesser extent. Rare variants have probably a large effect on disease progression in highly affected families. Furthermore, current prediction models do not include molecular risk factors, while these factors can be measured accurately in the blood. Possible promising molecular risk factors are High‐Density Lipoprotein Cholesterol (HDL‐C), Docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), zeaxanthin and lutein.

Summary

Phenotypic, demographic, environmental, genetic and molecular risk factors can be combined in prediction models to predict disease progression, but the selection of the proper risk factors for personalised risk prediction will differ among individuals and is dependent on their current disease stage. Future prediction models should include a wider set of genetic variants to determine the genetic risk more accurately, and rare variants should be taken into account in highly affected families. In addition, adding molecular factors in prediction models may lead to preventive strategies and personalised advice.

High-value chemicals from Botryococcus braunii and their current applications - A review

Botryococcus braunii is known for its high yield of extracellular hydrocarbons and polysaccharides. Hydrocarbons, especially botryococcenes and squalene can be used as not only fuels but also alternative feedstock for other fossil-based products. Exopolysaccharides excreted from B. braunii can be used as scaffolds for polyesters production, and have a notable potential for synthesis of nanoparticles. B. braunii is also a rich source of carotenoids, especially the unique secondary carotenoids such as botryoxanthins that have never been found in other microalgae. The morphology, physiology, and outer cell walls of B. braunii are complex. Understanding the colony structure shall provide insights into the mechanism of cell growth and chemicals secretion. It is possible to improve the production economics of the alga with advanced culture systems. Moreover, investigation of metabolic pathways for B. braunii may help us understand their regulation and provide valuable information for strain selection and optimal production of high-value chemicals.

Zeaxanthin Dipalmitate in the Treatment of Liver Disease

Goji berry, Lycium barbarum, has been widely used in traditional Chinese medicine (TCM), but its properties have not been studied until recently. The fruit is a major source of zeaxanthin dipalmitate (ZD), a xanthophyll carotenoid shown to benefit the liver. Liver disease is one of the most prevalent diseases in the world. Some conditions, such as chronic hepatitis B virus, liver cirrhosis, and hepatocellular carcinoma, remain incurable. Managing them can constitute an economic burden for patients and healthcare systems. Hence, development of more effective pharmacological drugs is warranted. Studies have shown the hepatoprotective, antifibrotic, antioxidant, anti-inflammatory, antiapoptotic, antitumor, and chemopreventive properties of ZD. These findings suggest that ZD-based drugs could hold promise for many liver disorders. In this paper, we reviewed the current literature regarding the therapeutic effects of ZD in the treatment of liver disease.