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

Stage-specific dynamics of macular pigment optical density as a prognostic biomarker in epiretinal membrane surgery

PURPOSE

To explore macular pigment optical density (MPOD) dynamics in stage 2 and stage 3 epiretinal membranes (ERMs) and to evaluate its pre and postoperative modifications. Furthermore, the study assessed the potential of MPOD as a prognostic biomarker in ERM management.

METHODS

A cohort of stage 2 (n=21) and 3 (n=20) ERM patients, matched for age and gender, underwent clinical evaluation at baseline and postoperative follow-up. Correlations between MPOD and optical coherence tomography parameters were analysed within each group.

RESULTS

Postoperative MPOD levels significantly differed between stage 2 and 3 ERM patients (p=0.027). Changes in MPOD over time (ΔMPOD) were significantly greater in stage 3 compared with stage 2 participants (p=0.018). In stage 2, ΔMPOD correlated with changes in best-corrected visual acuity (ΔBCVA) (r=0.398, p=0.074) and demonstrated a strong correlation with changes in outer nuclear layer thickness (r=0.672, p<0.001). In stage 3, ΔMPOD exhibited a significant negative correlation with changes in central foveal thickness (r=-0.547, p=0.013) and a positive correlation with ΔBCVA (r=0.510, p=0.022).

CONCLUSIONS

MPOD exhibited stage-specific dynamics and significant postoperative changes. Correlation between ΔMPOD and ΔBCVA in both stages highlights its potential role as a prognostic functional biomarker.

Influence of Dietary Habits on Macular Pigment in Childhood

Background/Objectives: To analyze the macular pigment optical density (MPOD) values in a child population and to evaluate the relation between MPOD and adherence to the Mediterranean diet using a validated questionnaire specially created for children. Eighty-eight children were included in this cross-sectional study from two primary education schools of Seville (Spain). Methods: MPOD values were measured using Macular Pigment Screener II ®. Lutein and Zeaxanthin intake was evaluated by KIDMED questionnaire, which classifies children according to adherence to the Mediterranean diet. A whole ocular exam with slit-lamp biomicroscopy was conducted by a specialized optometrist. Results: The mean age ranged between 6 and 8 years. The mean MPOD value was 0.46 ± 0.18. The mean score of the KIDMED questionnaire was 7.19 ± 1.85. No statistically significant differences were found as a function of gender or among Mediterranean diet adherence groups. No significant differences in MPOD values between answers were found in any KIDMED questions. No correlations were found for MPOD with several variables, such as Mediterranean diet adherence and KIDMED score. Conclusions: MPOD levels in children could not be correlated with Mediterranean Diet adherence and, thus, good dietary habits. Genetic characteristics, mother's diet habits, oxidative stress, and body fat composition in children could be the main factors influencing MPOD levels.

Dietary carotenoid intakes and biological aging among US adults, NHANES 1999-2018

BACKGROUND

Carotenoids have been shown to have multiple health benefits, including antioxidant and anti-inflammatory. The data for the effect of dietary specific carotenoids on biological aging is limited. Our study aims to examine the association between dietary carotenoid intake levels and biological aging.

METHODS

This cross-sectional study was performed among 27,338 adults from NHANES 1999-2018. Dietary intake was assessed through two 24-hour dietary recall interviews. Biological aging indices included allostatic load (AL), homeostatic dysregulation (HD), Klemera-Doubal method (KDM), and phenoAge (PA). Multiple linear regression, weighted quantile sum (WQS) regression and quantile g-computation (QG-comp) were used to explore the associations of single carotenoid and mixed carotenoids with biological aging.

RESULTS

Associations between dietary carotenoid intake levels and biological aging indices were significant among adults across the United States. Multiple linear regression showed that most carotenoids were significantly negatively correlated with AL (β = -0.017 - -0.011), HD (β = -0.045 - -0.032), KDM (β = -0.984 - -0.471), and PA (β = -0.975 - -0.539). Subgroup analysis indicated that male, older individuals, smokers, alcohol drinkers, and less physically active individuals are particularly sensitive populations. Meanwhile, WQS regression and QG-comp analyses consistently indicated a negative association between mixed carotenoids exposure and four biological aging indices, highlighting that lutein/zeaxanthin and β-carotene were responsible for the outcomes.

CONCLUSIONS

Increased dietary intakes of various carotenoids were associated with lower biological aging indices, which was possibly and mainly driven by lutein/zeaxanthin and β-carotene.

Engineering crystal network of supramolecular Oleogel via kinetical regulation for improved lutein bioaccessibility

This study presented an approach for controlling supramolecular oleogel crystal network by regulating kinetical factors - specifically, a combination of cooling temperature and aging period. Results indicated that only under long aging period, supramolecular oleogels prepared at different cooling temperature exhibited distinct crystal morphology compared to those under short aging period. The physicochemical properties of oleogels were affected by different crystal networks. Therefore, further research on oleogels under longed aging was explored. For lutein encapsulation, it was observed that supramolecular oleogels with denser crystal network exhibited higher lutein bioaccessibility. This was probably because the denser crystal network providing a solid physical barrier that effectively protected lutein unaffected by gastric acid degradation. Additionally, the micellar capacity was also enhanced to accommodate lutein due to release of long chain fatty acid from the gelator glycerol monostearate (GMS). Collectively, kinetical factors regulation facilitated rational design of oleogels for delivery of lipid-soluble bioactive compounds.

Pistachio Consumption Increases Macular Pigment Optical Density in Healthy Adults: A Randomized Controlled Trial

BACKGROUND

Pistachios are a bioavailable source of the xanthophyll lutein. Along with zeaxanthin, these plant pigments are major components of macular pigment (MP) in the human retina. MP can be non-invasively measured and is referred to as MP optical density (MPOD). MPOD is modifiable with dietary interventions that include lutein and zeaxanthin (L/Z). Higher MPOD protects the eye from light damage and is positively associated with eye health.

OBJECTIVES

This dietary intervention study aimed to evaluate the effect of pistachio consumption on MPOD.

METHODS

This single-blinded, randomized controlled trial compared a 12-week pistachio intervention (2 oz/d) with usual diet (UD) on MPOD and serum L/Z in middle-aged to older healthy adults (n = 36) in a 1:1 randomization scheme. Participants were selected for habitually low L/Z intake and low baseline MPOD. MPOD was measured using heterochromatic flicker photometry at 4 retinal eccentricities during baseline, week 6, and week 12 study visits. Serum L/Z was analyzed using high-performance liquid chromatography. Primary statistical analysis was conducted on an intent-to-treat basis using repeated-measure analysis of variance.

RESULTS

Compared with UD, MPOD of the participants in the pistachio intervention group (PIS) had significantly increased (P < 0.001) at all eccentricities over the initial 6-wk period. This increase was maintained at week 12. MPOD in the UD participants did not change during the 12-week period. Serum lutein concentration followed a similar pattern to MPOD; serum cis-lutein and zeaxanthin did not change in either group over the 12-wk intervention.

CONCLUSIONS

The results of our study demonstrate that a dietary intervention with pistachios is efficacious in increasing MPOD in healthy adults selected for habitually low intake of L/Z and low baseline MPOD. This suggests that pistachio consumption could be an effective dietary strategy for preserving eye health. Future studies need to evaluate the generalizability of our findings to other populations. This trial was registered at clinicaltrials.gov as NCT05283941.

Oral Antioxidant and Lutein/Zeaxanthin Supplements Slow Geographic Atrophy Progression to the Fovea in Age-Related Macular Degeneration

PURPOSE

To determine whether oral micronutrient supplementation slows geographic atrophy (GA) progression in age-related macular degeneration (AMD).

DESIGN

Post hoc analysis of Age-Related Eye Disease Study (AREDS) and AREDS2, multicenter randomized placebo-controlled trials of oral micronutrient supplementation, each with 2 × 2 factorial design.

PARTICIPANTS

A total of 392 eyes (318 participants) with GA in AREDS and 1210 eyes (891 participants) with GA in AREDS2.

METHODS

The AREDS participants were randomly assigned to oral antioxidants (500 mg vitamin C, 400 IU vitamin E, 15 mg β-carotene), 80 mg zinc, combination, or placebo. The AREDS2 participants were randomly assigned to 10 mg lutein/2 mg zeaxanthin, 350 mg docosahexaenoic acid/650 mg eicosapentaenoic acid, combination, or placebo. Consenting AREDS2 participants were also randomly assigned to alternative AREDS formulations: original; no beta-carotene; 25 mg zinc instead of 80 mg; both.

MAIN OUTCOME MEASURES

(1) Change in GA proximity to central macula over time and (2) change in square root GA area over time, each measured from color fundus photographs at annual visits and analyzed by mixed-model regression according to randomized assignments.

RESULTS

In AREDS eyes with noncentral GA (n = 208), proximity-based progression toward the central macula was significantly slower with randomization to antioxidants versus none, at 50.7 μm/year (95% confidence interval [CI], 38.0-63.4 μm/year) versus 72.9 μm/year (95% CI, 61.3-84.5 μm/year; P = 0.012), respectively. In AREDS2 eyes with noncentral GA, in participants assigned to AREDS antioxidants without β-carotene (n = 325 eyes), proximity-based progression was significantly slower with randomization to lutein/zeaxanthin versus none, at 80.1 μm/year (95% CI, 60.9-99.3 μm/year) versus 114.4 μm/year (95% CI, 96.2-132.7 μm/year; P = 0.011), respectively. In AREDS eyes with any GA (n = 392), area-based progression was not significantly different with randomization to antioxidants versus none (P = 0.63). In AREDS2 eyes with any GA, in participants assigned to AREDS antioxidants without β-carotene (n = 505 eyes), area-based progression was not significantly different with randomization to lutein/zeaxanthin versus none (P = 0.64).

CONCLUSIONS

Oral micronutrient supplementation slowed GA progression toward the central macula, likely by augmenting the natural phenomenon of foveal sparing.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Effect of Dietary Supplementation with Lutein, Zeaxanthin, and Elderberries on Dry Eye Disease (DED) and Immunity: A Randomized Controlled Trial

BACKGROUND/OBJECTIVES

Dry eye disease (DED) significantly impairs quality of life, affecting physical, social, and psychological well-being, as well as reducing workplace productivity. While lutein and zeaxanthin supplements have been shown to improve ocular health, existing research often overlooks the efficacy of lower dosages and shorter durations of supplementation. This study investigated the effects of combined supplementation with lutein, zeaxanthin, and elderberries in 110 voluntary participants through a randomized controlled trial.

METHODS

Participants took 6 mg of lutein and 1 mg of zeaxanthin, along with 100 mg elderberry extract once daily for a duration of 20 days. Ocular health was assessed using the Ocular Surface Disease Index (OSDI), while immune status was evaluated with the Immune Status Questionnaire (ISQ).

RESULTS

Results showed that combined supplementation significantly (p < 0.05) reduced the OSDI scores in the intervention group from 38.15 ± 11.14 to 18.26 ± 5.57, reflecting a 52.2% reduction. A similar trend was observed with the Visual Analog Scale (VAS), indicating significant (p < 0.05) improvement from 5.31 ± 1.62 to 6.73 ± 1.74, equivalent to a 26.7% improvement. Although the intervention group showed a 15.9% improvement in ISQ scores by the study's end, this was not significantly different from the placebo group, suggesting that higher dosages or longer durations may be needed to observe a meaningful effect. Additionally, findings from the Food Frequency Questionnaire revealed that the average dietary intake of lutein and zeaxanthin among participants was only 663.49 µg, equating to just 5.5% of the suggested optimal daily intake. This low consumption is concerning, as it is inversely correlated with the risk of ocular diseases.

CONCLUSIONS

Collectively, these findings support the use of combined supplementation as an adjuvant approach to improving ocular health.

Lutein improves remyelination by reducing of neuroinflammation in C57BL/6 mouse models of multiple sclerosis

Multiple sclerosis (MS) is an inflammatory neurodegenerative disorder characterized by demyelination. Lutein, a xanthophyll carotenoid, has well-known antioxidant and anti-inflammatory properties. In this experiment, we aimed to investigate the neuroprotective and remyelination potential of lutein in comparison with dimethyl fumarate (DMF) as a reference drug in post-cuprizone-intoxicated C57BL/6 mice. Lutein (50, 100, and 200 mg/kg/day; p.o.) and DMF (15 mg/kg/day, i.p.) were administered either alone or in combination for three weeks at the end of the six-week cuprizone (0.2 % w/w) feeding period. At the end of the study, behavioral tests, histopathological staining, immunohistochemistry (olig2), ELISA, and real-time PCR were performed to evaluate the target parameters. Lutein treatment significantly enhanced motor functions, reversed cuprizone-induced demyelination and increased serum TAC. In addition, treatment with lutein increased the number of Olig2+ cells in the corpus callosum, reduced the IL-1β and TNF-α and increased BDNF. Lutein administration significantly increased the expression levels of genes involved in myelin production (MBP, PLP, MOG, MAG, and OLIG-1) and notably reduced GFAP expression levels. In the present study, our results showed that lutein treatment could promote remyelination and neuroprotective effects by reducing neuroinflammation and upregulating the expression of the genes involved in myelin formation These findings suggest that lutein could serve as a potential adjuvant therapy for patients with multiple sclerosis. Further clinical trials are necessary to confirm its efficacy.

Bioactivity and Bioavailability of Carotenoids Applied in Human Health: Technological Advances and Innovation

This article presents a groundbreaking perspective on carotenoids, focusing on their innovative applications and transformative potential in human health and medicine. Research jointly delves deeper into the bioactivity and bioavailability of carotenoids, revealing therapeutic uses and technological advances that have the potential to revolutionize medical treatments. We explore pioneering therapeutic applications in which carotenoids are used to treat chronic diseases such as cancer, cardiovascular disease, and age-related macular degeneration, offering novel protective mechanisms and innovative therapeutic benefits. Our study also shows cutting-edge technological innovations in carotenoid extraction and bioavailability, including the development of supramolecular carriers and advanced nanotechnology, which dramatically improve the absorption and efficacy of these compounds. These technological advances not only ensure consistent quality but also tailor carotenoid therapies to each patient's health needs, paving the way for personalized medicine. By integrating the latest scientific discoveries and innovative techniques, this research provides a prospective perspective on the clinical applications of carotenoids, establishing a new benchmark for future studies in this field. Our findings underscore the importance of optimizing carotenoid extraction, administration, bioactivity, and bioavailability methods to develop more effective, targeted, and personalized treatments, thus offering visionary insight into their potential in modern medical practices.

Association between circulating antioxidants and sleep disorders: comprehensive results from NHANES 2017-2018

Background: Oxidative stress plays an important role in the occurrence and pathological process of numerous human diseases. A bidirectional relationship was found between sleep disorders and oxidative stress. However, the association between circulating antioxidant levels and the risk of sleep disorders at the population-scale has yet to be determined. Methods: We used the dataset from the National Health and Nutrition Examination Survey (NHANES) 2017-2018 data release cycle and included 3062 adult participants aged 25-75 years. The circulating antioxidants levels in serum were measured, and the sleep status was assessed by self-reported sleep disorder questionnaire tests. We investigated the association and exposure-response relationship between the 12 main circulating antioxidants and sleep disorders using a generalized additive model (GAM), multiple linear, binary logistic, and restricted cubic spline (RCS) regression models. Multiple sensitivity analyses were conducted to validate the results of our study. Results: Significantly lower serum concentrations of ten antioxidants were observed in the group which had trouble sleeping symptoms compared to the control group. After adjusting for all the covariates, the binary logistic regression models indicated that six of the circulating antioxidants including alpha-carotene, alpha-cryptoxanthin, trans-beta-carotene, beta-cryptoxanthin, lutein and zeaxanthin, and vitamin C, showed a significant association with the risk of overall trouble sleeping symptoms, with odds ratios corresponding to 0.88 (95% CI: 0.80-0.96), 0.74 (95% CI: 0.62-0.87), 0.87 (95% CI: 0.79-0.97), 0.85 (95% CI: 0.75-0.95), 0.72 (95% CI: 0.61-0.84), and 0.83 (95% CI: 0.74-0.93), respectively. The GAM and multiple linear regression revealed similar associations whereas the RCS regression models further confirmed their significant negative exposure-response relationship. Conclusions: The circulating carotenoids and vitamin C levels were negatively correlated with the risk of sleep disorders. Higher circulating antioxidant levels were significantly associated with a lower risk of sleep disorders. The potential health risk of low circulating antioxidants levels was higher in the female population than in the male population.

Visual fatigue a comprehensive review of mechanisms of occurrence, animal model design and nutritional intervention strategies

When the eyes work intensively, it is easy to have eye discomfort such as blurred vision, soreness, dryness, and tearing, that is, visual fatigue. Visual fatigue not only affects work and study efficiency, but long-term visual fatigue can also easily affect physical and mental health. In recent years, with the popularization of electronic products, although it has brought convenience to the office and study, it has also caused more frequent visual fatigue among people who use electronic devices. Moreover, studies have reported that the number of people with visual fatigue is showing a trend of increasing year by year. The range of people involved is also extensive, especially students, people who have been engaged in computer work and fine instruments (such as microscopes) for a long time, and older adults with aging eye function. More and more studies have proposed that supplementation with the proper nutrients can effectively relieve visual fatigue and promote eye health. This review discusses the physiological mechanisms of visual fatigue and the design ideas of animal experiments from the perspective of modern nutritional science. Functional food ingredients with the ability to alleviate visual fatigue are discussed in detail.

Mechanistic Understanding of the Antiviral Properties of Pistachios and Zeaxanthin against HSV-1

The search for alternative clinical treatments to fight resistance and find alternative antiviral treatments for the herpes simplex virus (HSV) is of great interest. Plants are rich sources of novel antiviral, pharmacologically active agents that provide several advantages, including reduced side effects, less resistance, low toxicity, and different mechanisms of action. In the present work, the antiviral activity of Californian natural raw (NRRE) and roasted unsalted (RURE) pistachio polyphenols-rich extracts was evaluated against HSV-1 using VERO cells. Two different extraction methods, with or without n-hexane, were used. Results showed that n-hexane-extracted NRRE and RURE exerted an antiviral effect against HSV-1, blocking virus binding on the cell surface, affecting viral DNA synthesis as well as accumulation of ICP0, UL42, and Us11 viral proteins. Additionally, the identification and quantification of phenolic compounds by RP-HPLC-DAD confirmed that extraction with n-hexane exclusively accumulated tocopherols, carotenoids, and xanthophylls. Amongst these, zeaxanthin exhibited strong antiviral activity against HSV-1 (CC50: 16.1 µM, EC50 4.08 µM, SI 3.96), affecting both the viral attachment and penetration and viral DNA synthesis. Zeaxanthin is a dietary carotenoid that accumulates in the retina as a macular pigment. The use of pistachio extracts and derivates should be encouraged for the topical treatment of ocular herpetic infections.

Autophagy Activation Promoted by Pulses of Light and Phytochemicals Counteracting Oxidative Stress during Age-Related Macular Degeneration

The seminal role of autophagy during age-related macular degeneration (AMD) lies in the clearance of a number of reactive oxidative species that generate dysfunctional mitochondria. In fact, reactive oxygen species (ROS) in the retina generate misfolded proteins, alter lipids and sugars composition, disrupt DNA integrity, damage cell organelles and produce retinal inclusions while causing AMD. This explains why autophagy in the retinal pigment epithelium (RPE), mostly at the macular level, is essential in AMD and even in baseline conditions to provide a powerful and fast replacement of oxidized molecules and ROS-damaged mitochondria. When autophagy is impaired within RPE, the deleterious effects of ROS, which are produced in excess also during baseline conditions, are no longer counteracted, and retinal degeneration may occur. Within RPE, autophagy can be induced by various stimuli, such as light and naturally occurring phytochemicals. Light and phytochemicals, in turn, may synergize to enhance autophagy. This may explain the beneficial effects of light pulses combined with phytochemicals both in improving retinal structure and visual acuity. The ability of light to activate some phytochemicals may further extend such a synergism during retinal degeneration. In this way, photosensitive natural compounds may produce light-dependent beneficial antioxidant effects in AMD.

The Essential Role of Light-Induced Autophagy in the Inner Choroid/Outer Retinal Neurovascular Unit in Baseline Conditions and Degeneration

The present article discusses the role of light in altering autophagy, both within the outer retina (retinal pigment epithelium, RPE, and the outer segment of photoreceptors) and the inner choroid (Bruch's membrane, BM, endothelial cells and the pericytes of choriocapillaris, CC). Here autophagy is needed to maintain the high metabolic requirements and to provide the specific physiological activity sub-serving the process of vision. Activation or inhibition of autophagy within RPE strongly depends on light exposure and it is concomitant with activation or inhibition of the outer segment of the photoreceptors. This also recruits CC, which provides blood flow and metabolic substrates. Thus, the inner choroid and outer retina are mutually dependent and their activity is orchestrated by light exposure in order to cope with metabolic demand. This is tuned by the autophagy status, which works as a sort of pivot in the cross-talk within the inner choroid/outer retina neurovascular unit. In degenerative conditions, and mostly during age-related macular degeneration (AMD), autophagy dysfunction occurs in this area to induce cell loss and extracellular aggregates. Therefore, a detailed analysis of the autophagy status encompassing CC, RPE and interposed BM is key to understanding the fine anatomy and altered biochemistry which underlie the onset and progression of AMD.

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.