Lutein across the Lifespan: From Childhood Cognitive Performance to the Aging Eye and Brain

Evolving perspectives on lutein production from microalgae - A focus on productivity and heterotrophic culture

Increased consumer awareness for healthier and more sustainable products has driven the search for naturally sourced compounds as substitutes for chemically synthesized counterparts. Research on pigments of natural origin, such as carotenoids, particularly lutein, has been increasing for over three decades. Lutein is recognized for its antioxidant and photoprotective activity. Its ability to cross the blood-brain barrier allows it to act at the eye and brain level and has been linked to benefits for vision, cognitive function and other conditions. While marigold flower is positioned as the only crop from which lutein is extracted from and commercialized, microalgae are proposed as an alternative with several advantages over this terrestrial crop. The main barrier to scaling up lutein production from microalgae to the commercial level is the low productivity compared to the high costs. This review explores strategies to enhance lutein production in microalgae by emphasizing the overall productivity over lutein content alone. Evaluation of how culture parameters, such as light quality, nitrogen sufficiency, temperature and even stress factors, affect lutein content and biomass development in batch phototrophic cultures was performed. Overall, the total lutein production remains low under this metabolic regime due to the low biomass productivity of photosynthetic batch cultures. For this reason, we describe findings on microalgal cultures grown under different metabolic regimes and culture protocols (fed-batch, pulse-feed, semi-batch, semi-continuous, continuous). After a careful literature examination, two-step heterotrophic or mixotrophic cultivation strategies are suggested to surpass the lutein productivity achieved in single-step photosynthetic cultures. Furthermore, this review highlights the urgent need to develop technical feasibility studies at a pilot scale for these cultivation strategies, which will strengthen the necessary techno-economic analyses to drive their commercial production.

Lutein supplementation for early-life health and development: current knowledge, challenges, and implications

Macular carotenoids, which consist of lutein, zeaxanthin, and meso-zeaxanthin, are dietary antioxidants and macular pigments in the eyes, protecting the macula from light-induced oxidative stress. Lutein is also the main carotenoid in the infant brain and is involved in cognitive development. While a few articles reviewed the role of lutein in early health and development, the current review is the first that focuses on the outcomes of lutein supplementation, either provided to mothers or to infants. Additionally, lutein status and metabolism during pregnancy and lactation, factors that limit the potential application of lutein as a nutritional intervention, and solutions to overcome the limitation are also discussed. In brief, the lutein intake in pregnant and lactating women in the United States may not be optimal. Furthermore, preterm and formula-fed infants are known to have compromised lutein status compared to term and breast-fed infants, respectively. While lutein supplementation via both maternal and infant consumption improves lutein status in infants, the application of lutein as a nutritional intervention may be compromised by its low bioavailability. Various encapsulation techniques have been developed to enhance the delivery of lutein in adult animals or human but should be further evaluated in neonatal models.

Lutein and Zeaxanthin Supplementation Improves Dynamic Visual and Cognitive Performance in Children: A Randomized, Double-Blind, Parallel, Placebo-Controlled Study

INTRODUCTION

Supplementation with dietary neuro-pigments lutein (L) and zeaxanthin (Z) has been shown to improve many aspects of visual and cognitive function in adults. In this study, we tested whether a similar intervention could improve such outcomes in preadolescent children.

METHODS

Sixty children (age range 5-12 years) were randomized in a 2:1 ratio in this double-blind, placebo-controlled clinical trial. Subjects were supplemented with gummies containing either a combination of 10 mg lutein and 2 mg zeaxanthin (LZ) or placebo for 180 days. Macular pigment optical density (MPOD) was the primary endpoint. The secondary endpoints included serum levels of L and Z, and brain-derived neurotrophic factor (BDNF), critical flicker fusion (CFF), eye strain and fatigue using visual analogue scales (VAS), Children's Sleep Habits Questionnaire-Abbreviated (CSHQ-A), and Creyos Health cognitive domains like attention, focus/concentration, episodic memory and learning, visuospatial working memory, and visuospatial processing speed. Safety was assessed throughout the study on the basis of physical examination, vital signs, clinical laboratory tests, and monitoring of adverse events.

RESULTS

The LZ group showed significant increases in MPOD at all visits post-supplementation, with significant increases as early as day 42 compared to placebo. The LZ group showed significant increases in serum lutein levels, reduced eye strain and fatigue, and improved cognitive performance (focus, episodic memory and learning, visuospatial working memory) at days 90 and 180 compared to placebo. Further, the LZ group showed significant increases in processing speed (CFF), attention, visuospatial processing, and serum Z and BDNF levels on day 180 compared to placebo. No safety concerns were observed.

CONCLUSIONS

Supplementing LZ resulted in increased MPOD levels, along with increased serum levels of L, Z, and BDNF. These changes were associated with improved visual and cognitive performances and reduction in eye strain and eye fatigue in the children receiving LZ gummies. The investigational product was safe and well tolerated.

TRIAL REGISTRATION

http://ctri.nic.in/ Identifier CTRI/2022/05/042364.

Developing biopolymer-stabilized emulsions for improved stability and bioaccessibility of lutein

Lutein is essential for infant visual and cognitive development but has low stability and solubility. This study aimed to enhance the stability and bioaccessibility of lutein using oil-in-water emulsions stabilized with biopolymers. Commercially available octenylsuccinylated (OS) starches, including capsule TA® (CTA), HI-CAP®100 (HC), and Purity Gum® 2000 (PG), along with gum Arabic (GA) variants Ticaloid acacia Max® (TAM), TICAmulsion® 3020 (TM), and pre-hydrate gum Arabic (PHGA), were chosen as emulsifiers. By screening the effect of biopolymer concentration and oil volume fraction (Φ), emulsions stabilized with CTA, HC, or TM at 20% and 30% (w/v) concentration and 70% Φ exhibited a gel-like structure and were selected for further assessments. After a week at 25 °C, emulsions stabilized by CTA and HC showed no significant change in droplet size, while TM emulsion exhibited a 1.58-fold increase. At 45 °C, all emulsions exhibited increase in droplet size. Lutein retention is higher in CTA emulsions at both storage temperatures than free lutein. In vitro bioaccessibility of all lutein emulsions was higher than that of free lutein. These findings highlight the superior stability and bioaccessibility of the lutein emulsion stabilized by OS starch, positioning it as a promising carrier to broaden lutein applications in infant foods.

Maternal Lutein Intake during Pregnancies with or without Gestational Diabetes Mellitus and Cognitive Development of Children at 2 Years of Age: A Prospective Observational Study

Lutein and its isomer zeaxanthin serve as antioxidants and preserve cognitive function during aging. However, whether lutein/zeaxanthin (L + Z) exposure early in life improves cognitive development of children is rarely explored. It is also unknown whether gestational diabetes mellitus (GDM), characterized by heightened oxidative stress, affects lutein metabolism. This prospective longitudinal cohort study examined the differences in L + Z intake and metabolism, as well as the association between maternal L + Z intake and children's cognitive development in GDM versus non-GDM pregnancies. Seventy-six pregnant women (n = 40 with GDM) were recruited between 25 and 33 weeks of gestation and dietary intakes were recorded. At delivery, cord blood was collected, and 2 years later, the Bayley III developmental test was conducted on a subset of children (n = 38). The results suggest that GDM reduced cord blood lutein levels at birth; L + Z intake during pregnancy was associated with better cognitive (β = 0.003, p = 0.001) and language (β = 0.002, p = 0.038) scoring of children at 2 years regardless of GDM status. In conclusion, maternal L + Z intake was positively associated with children's developmental scores, regardless of GDM. More studies are needed to confirm such associations.

Oxidative stress, the blood-brain barrier and neurodegenerative diseases: The critical beneficial role of dietary antioxidants

In recent years, growing awareness of the role of oxidative stress in brain health has prompted antioxidants, especially dietary antioxidants, to receive growing attention as possible treatments strategies for patients with neurodegenerative diseases (NDs). The most widely studied dietary antioxidants include active substances such as vitamins, carotenoids, flavonoids and polyphenols. Dietary antioxidants are found in usually consumed foods such as fresh fruits, vegetables, nuts and oils and are gaining popularity due to recently growing awareness of their potential for preventive and protective agents against NDs, as well as their abundant natural sources, generally non-toxic nature, and ease of long-term consumption. This review article examines the role of oxidative stress in the development of NDs, explores the 'two-sidedness' of the blood-brain barrier (BBB) as a protective barrier to the nervous system and an impeding barrier to the use of antioxidants as drug medicinal products and/or dietary antioxidants supplements for prevention and therapy and reviews the BBB permeability of common dietary antioxidant suplements and their potential efficacy in the prevention and treatment of NDs. Finally, current challenges and future directions for the prevention and treatment of NDs using dietary antioxidants are discussed, and useful information on the prevention and treatment of NDs is provided.

Systemic Effects of Prenatal Carotenoid Supplementation in the Mother and her Child: The Lutein and Zeaxanthin in Pregnancy (L-ZIP) Randomized Trial -Report Number 1

BACKGROUND

Adding carotenoids, particularly lutein (L) and zeaxanthin (Z), to prenatal micronutrient formulations has been promoted to enhance infant visual and neural development and to maintain maternal health. Although these claims are biologically plausible, they are not yet supported by a compelling prospective trial.

OBJECTIVE

We investigated the effect of prenatal carotenoid supplementation on biomarkers of maternal and infant systemic carotenoid status.

METHODS

We randomly assigned 47 first trimester pregnant subjects by 1:1 allocation to receive standard-of-care prenatal vitamins plus a 10 mg L and 2 mg Z softgel (the Carotenoid group) or standard-of-care prenatal vitamins with a placebo softgel (the Control group) for 6-8 mo. Maternal carotenoid concentrations in the serum and skin at the end of each trimester and postpartum were measured with HPLC and resonance Raman spectroscopy, respectively. Infants' systemic carotenoid status was assessed using similar techniques but optimized for infants. Repeated measures and paired t-tests were determined, and a P value < 0.05 was considered statistically significant.

RESULTS

After supplementation, there was a statistically significant increase in maternal serum L + Z concentrations, serum total carotenoid concentrations, and skin carotenoid status (P < 0.001 for all) in the Carotenoid group relative to the Control group at all study time points. Similarly, infants whose mothers were in the Carotenoid group had a significant 5-fold increase in cord blood L + Z concentrations, over a 3-fold increase in cord blood total carotenoids, and a 38% increase in skin carotenoids compared with the Control group (P < 0.0001 for all). In addition, there was a strong positive, statistically significant correlation between postpartum maternal and infant systemic carotenoid status (P < 0.0001).

CONCLUSION

Prenatal carotenoid supplementation significantly increased maternal and infant systemic (skin and serum) carotenoid status, which may benefit pregnant women and their infants' health. This trial was registered at clinicaltrials.gov as NCT03750968.

Nutritional Composition of Hass Avocado Pulp

Avocados (Persea americana) are a unique fruit that can provide health benefits when included in a healthy diet. As health care moves towards precision health and targeted therapies or preventative medicine, it is critical to understand foods and their dietary components. The nutritional composition and plant physiology of the Hass avocado is strikingly different from other fruits. This paper reviews the nutrient and bioactive composition of the edible portion of the Hass avocado (pulp) reported in the literature and from commercial lab analyses of the current market supply of fresh Hass avocados. These results provide comprehensive data on what nutrients and bioactives are in avocado and the quantity of these nutrients. We discuss the reasons for nutrient composition variations and review some potential health benefits of bioactive compounds found in Hass avocados.

A comprehensive review on infant formula: nutritional and functional constituents, recent trends in processing and its impact on infants' gut microbiota

Human milk is considered the most valuable form of nutrition for infants for their growth, development and function. So far, there are still some cases where feeding human milk is not feasible. As a result, the market for infant formula is widely increasing, and formula feeding become an alternative or substitute for breastfeeding. The nutritional value of the formula can be improved by adding functional bioactive compounds like probiotics, prebiotics, human milk oligosaccharides, vitamins, minerals, taurine, inositol, osteopontin, lactoferrin, gangliosides, carnitine etc. For processing of infant formula, diverse thermal and non-thermal technologies have been employed. Infant formula can be either in powdered form, which requires reconstitution with water or in ready-to-feed liquid form, among which powder form is readily available, shelf-stable and vastly marketed. Infants' gut microbiota is a complex ecosystem and the nutrient composition of infant formula is recognized to have a lasting effect on it. Likewise, the gut microbiota establishment closely parallels with host immune development and growth. Therefore, it must be contemplated as an important factor for consideration while developing formulas. In this review, we have focused on the formulation and manufacturing of safe and nutritious infant formula equivalent to human milk or aligning with the infant's needs and its ultimate impact on infants' gut microbiota.

Macular Pigment, Cognition, and Visual Function in Younger Healthy Adults in Ghana

BACKGROUND

Macular pigment optical density (MPOD) remains an indispensable biomarker to measure fruit and vegetable intake, with a biologically plausible correlation to vision and cognition. However, evidence in the sub-Saharan regions, including Ghana, is lacking.

OBJECTIVE

This study explored dietary carotenoid intake on MPOD and its influence on cognitive and visual function in a healthy Ghanaian sample.

METHODS

The MPOD of 301 healthy subjects (aged 21.1±1.9 years) was evaluated using the customized Macular DensitometerTM. A battery of cognitive tests and standard vision assessments were employed to assess cognition and visual function, respectively. Dietary lutein and zeaxanthin (L and Z) were estimated based on a twenty-four-hour repeated dietary recall.

RESULTS

The mean MPOD at 0.5° and 1.0° eccentricities were 0.37±0.16 and 0.34±0.15 optical density units, respectively. Dietary intake of L (4.06±10.54 mg/day) was considerably higher than Z (0.33±2.25 mg/day), with cumulative L+Z estimated at 4.39±11.58 mg/day. MPOD was not significantly influenced by demographic, dietary, and visual measures (p≥0.05). However, after statistical adjustment, we found a small but statistically significant positive relationship between F-A-S phonemic verbal fluency (Unstandardized co-efficient (β) = 0.002, p = 0.016) and the never consumed alcohol category (β= 0.062, p = 0.02) with MPOD.

CONCLUSION

The findings in this population showed significant positive relationships between measures of cognition and no alcohol intake, with MPOD. These findings necessitate dietary education to augment carotenoid intake and limit alcohol intake for better cognitive functioning.

Influence of a 12-Month Structured Exercise Program on the Micronutrient-Cognitive Fitness-Physical Association Profiles in Mild Cognitive Impairment

Background

Preventive lifestyle strategies have shown promise to slow down or prevent age-related cognitive decline. However, evidence on the reciprocal longitudinal relationships between nutrition biomarkers and cognitive and physical performance is lacking. Studying nutritional, cognitive, and physical profiles over time may help to overcome this knowledge gap.

Objective

To investigate the relationship of plasma levels of the robust nutritional- and antioxidant defense-related biomarkers carotenoids and tocopherols with both indicators of cognitive and physical performance in persons with mild cognitive impairment (MCI) participating in a structured exercise program.

Methods

Data from 40 participants with MCI of the NeuroExercise study were analyzed. Participants had undergone a blood withdrawal for the analysis of plasma concentrations of six carotenoids, two tocopherols and retinol prior to and after one-year of structured exercise. All participants had undergone a broad spectrum of cognitive and physical performance tests.

Results

Significant associations between lipophilic micronutrients and cognitive/physical measures were observed that were previously found to play a role in cognitive and physical frailty. In particular, lutein, zeaxanthin, and lycopene are confirmed as robust, reliable, and stable indicators of nutritional defense. Importantly, these micronutrients were associated with cognitive measures prior to the physical training program and to a more prominent extent with indicators of motoric function after the physical exercise program.

Conclusion

Specific profiles of lipophilic micronutrients are associated to cognitive performance measures and, especially after a structured exercise program, to indicators of physical performance.

Nanoscale Delivery Systems of Lutein: An Updated Review from a Pharmaceutical Perspective

Carotenoids are natural lipid-soluble pigments that produce yellow to red colors in plants as well as providing bright coloration in vegetables and fruits. Lutein belongs to the xanthophyll subgroup of the carotenoid family, which plays an essential role in photosynthesis and photoprotection in nature. In the human body, lutein, together with its isomer zeaxanthin and its metabolite meso-zeaxanthin, accumulates in the macula of the eye retina, which is responsible for central, high-resolution, and color vision. As a bioactive phytochemical, lutein has essential physiological functions, providing photoprotection against damaging blue light, along with the neutralization of oxidants and the preservation of the structural and functional integrity of cellular membranes. As a potent antioxidant and anti-inflammatory agent, lutein unfortunately has a low bioavailability because of its lipophilicity and a low stability as a result of its conjugated double bonds. In order to enhance lutein stability and bioavailability and achieve its controlled delivery to a target, nanoscale delivery systems, which have great potential for the delivery of bioactive compounds, are starting to be employed. The current review highlights the advantages and innovations associated with incorporating lutein within promising nanoscale delivery systems, such as liposomes, nanoemulsions, polymer nanoparticles, and polymer–lipid hybrid nanoparticles, as well as their unique physiochemical properties.

The Role of Antioxidants in the Interplay between Oxidative Stress and Senescence

Cellular senescence is an irreversible state of cell cycle arrest occurring in response to stressful stimuli, such as telomere attrition, DNA damage, reactive oxygen species, and oncogenic proteins. Although beneficial and protective in several physiological processes, an excessive senescent cell burden has been involved in various pathological conditions including aging, tissue dysfunction and chronic diseases. Oxidative stress (OS) can drive senescence due to a loss of balance between pro-oxidant stimuli and antioxidant defences. Therefore, the identification and characterization of antioxidant compounds capable of preventing or counteracting the senescent phenotype is of major interest. However, despite the considerable number of studies, a comprehensive overview of the main antioxidant molecules capable of counteracting OS-induced senescence is still lacking. Here, besides a brief description of the molecular mechanisms implicated in OS-mediated aging, we review and discuss the role of enzymes, mitochondria-targeting compounds, vitamins, carotenoids, organosulfur compounds, nitrogen non-protein molecules, minerals, flavonoids, and non-flavonoids as antioxidant compounds with an anti-aging potential, therefore offering insights into innovative lifespan-extending approaches.

From Foods to Chemotherapeutics: The Antioxidant Potential of Dietary Phytochemicals

Food plants have been recognized for their medicinal properties for millennia, a concept supported by epidemiological studies indicating long-term health benefits for people consuming greater amounts of fruits and vegetables. As our technology and instrumentation advance, researchers have the ability to identify promising phytochemicals, and examine their potential benefits, or detriments, to human health. While results from trials investigating single chemical supplementation have sometimes produced negative health results, studies investigating the synergistic action of phytochemicals—either within our diet or as an adjuvant to radiation or chemotherapy—appear promising. Utilizing phytochemicals as synergistic agents may lower the chemotherapeutic doses needed to incur physiological results, while also using chemicals with fewer toxic effects. This review investigates a variety of plant-produced chemicals humans typically ingest, their impacts on overall health patterns, molecular mechanisms associated with their health impacts, and the potential of their synergistic use for therapeutic purposes.

Glycosylation of Zein Hydrolysate as a Nanocarrier for Lutein Delivery: Preparation and Stability

Lutein is a functional carotenoid that has a wide range of physiological benefits in humans. However, it easily degrades and becomes inactivated during storage and processing, resulting in low bioavailability. The development of new nanocarriers can effectively improve the stability and biological activity of lutein. In this study, zein hydrolysate (ZH) carriers were glycosylated with glucosamine (GLU) under the action of transglutaminase, and lutein-loaded glycosylated ZH nanoparticles (GZH-LUT) were constructed by liquid–liquid dispersion. The results showed that the GZH-LUT particles had a narrow size distribution in the range of 200–300 nm and a decreased zeta potential and polydispersity index. In particular, GZH trapped lutein more efficiently than ZH. In addition, GZH-LUT had better physical and chemical properties, including better water solubility, oxidative stability, and environmental stability than free lutein and ZH-LUT. These results indicate that glycosylated zein hydrolysate has the potential to be used as a novel protein-based nanocarrier to enhance the solubility and stability of lutein, which can further improve its bioavailability.

Sex Differences Across the Life Course: A Focus On Unique Nutritional and Health Considerations among Women

In the United States, women, while having a longer life expectancy than men, experience a differential risk for chronic diseases and have unique nutritional needs based on physiological and hormonal changes across the life span. However, much of what is known about health is based on research conducted in men. Additional complexity in assessing nutritional needs within gender include the variations in genetics, body compositions, hormonal milieus, underlying chronic diseases, and medication usage, with this list expanding as we consider these variables across the life course. It is clear women experience nutrient shortfalls during key periods of their lives, which may differentially impact their health. Consequently, as we move into the era of precision nutrition, understanding these sex- and gender-based differences may help optimize recommendations and interventions chosen to support health and weight management. Recently, a scientific conference was convened with content experts to explore these topics from a life-course perspective at biological, physiological, and behavioral levels. This publication summarizes the presentations and discussions from the workshop and provides an overview of important nutrition and related lifestyle considerations across the life course. The landscape of addressing female-specific nutritional needs continues to grow; now more than ever, it is essential to increase our understanding of the physiological differences between men and women, and determine how these physiological considerations may aid in optimizing nutritional strategies to support certain personal goals related to health, quality of life, sleep, and exercise performance among women.

Identification of Carotenoids in Hairless Canary Seed and the Effect of Baking on Their Composition in Bread and Muffin Products

Carotenoids are essential components in the human diet due to their positive functions in ocular and cognitive health. This study investigated composition of carotenoids in hairless canary seed (HCS) as a novel food and the effect of baking on carotenoids in bread and muffin made from HCS, wheat and corn. Three bread formulations made from wheat and HCS blends were evaluated and compared with control wheat bread. In addition, three low-fat muffin recipes prepared from HCS alone or in blends with corn were assessed. The fate of carotenoid compounds in breads and muffins was monitored after dry mixing, dough/batter formation and oven baking. Carotenoids in products were quantified using UPLC and their identification was confirmed based on LC-MS/MS. Hairless canary seed and corn were fairly rich in carotenoids with a total content of 7.6 and 12.9 µg/g, respectively, compared with wheat (1.3 µg/g). Nineteen carotenoid compounds were identified, with all-trans lutein being the principal carotenoid in HCS followed by lutein 3-O-linoleate, lutein 3-O-oleate and lutein di-linoleate. There were significant reductions in carotenoids in muffin and bread products. It appears that batter or dough preparation causes more reductions in carotenoids than oven baking, probably due to enzymatic oxidation and degradation. Muffin-making resulted in lower lutein reductions compared with the bread-making process. The results suggest that muffins made from hairless canary seed alone or in blends with corn could boost the daily intake of lutein and/or zeaxanthin.

US Older Adults That Consume Avocado or Guacamole Have Better Cognition Than Non-consumers: National Health and Nutrition Examination Survey 2011-2014

Purpose: The goal of this study is to examine how avocado relates to cognitive function among older adults. Methods: A total of 2,886 National Health and Nutrition Examination Survey 2011-2014 participants aged 60 or older met the eligibility criteria and were included of our cross-sectional study. Participants were binarily classified as avocado consumers (i.e., reported consuming any avocado/guacamole in either 24-h dietary recalls) or non-consumers. Cognitive performance was evaluated with: Consortium to Establish a Registry for Alzheimer's disease (CERAD)-immediate and delayed recall (IWR/DWR), the Animal Fluency test, and the Digit Symbol Substitution Test. We calculated the education-dependent z-scores for each subject because education level can impact cognitive function. Global cognitive score, an average of the z-scores for each cognitive test, was calculated in participants who had completed all four tests. To account for relevant covariates, we tested for mean differences in cognition between consumers and non-consumers using independent sample t-tests and ANCOVA, special cases of ordinary least squares regression. Results: Avocado consumers had significantly better cognitive scores across all cognitive tests and the global cognition score (p < 0.05) in the unadjusted model. Some mean differences attenuated after adjusting for potential confounders, but others remained significant. Compared to non-consumers, avocado consumers had significantly higher z-scores of 0.15, 0.15, and 0.11 for CERAD IWR and DWR, and global cognition score, respectively (all p < 0.05 in adjusted models). Conclusion: Avocado consumption was associated with significantly better IWR, DWR, and the overall global cognition score, which remained significant when controlling for all relevant confounders.

Lutein and Zeaxanthin in the Lipid Bilayer-Similarities and Differences Revealed by Computational Studies

Lutein and zeaxanthin are two similar carotenoids of the xanthophyll subgroup. Carotenoids are synthesized almost entirely by plants but are also present in significant amounts in animals. They are essential components of the lipid matrix of biomembranes, and one of their functions is to protect cells from light radiation, free radicals and oxidative stress. Carotenoids, depending on their chemical structure, can locate at various positions and in different orientations in the bilayer. Xanthophylls (XAN) are polar and in the bilayer are positionally restricted. In the case of lutein and zeaxanthin, whose both ionone rings are hydroxy-substituted and as such are anchored in the lipid bilayer interfaces, the position is generally transmembrane. However, both experimental and computer modelling studies indicate that lutein can also locate horizontally below the bilayer interface. This location has never been observed for zeaxanthin. To find a molecular-level explanation for the difference in the orientations of the XAN molecules in the bilayer, a number of phosphatidylcholine-XAN bilayers were constructed and molecular dynamics (MD) simulated for 1.1 µs each. The all-trans XAN molecules were initially placed either parallel or perpendicular to the bilayer surface. With the exception of one lutein, the horizontally placed molecules adopted the transmembrane orientation within 100-600 ns. On the basis of detailed analyses of the XAN orientations and the numbers and lifetimes of their interactions in the bilayer, a plausible explanation is offered as to why a lutein molecule may remain in the horizontal orientation while zeaxanthin does not. Contrary to common believe, lutein horizontal orientation is not related to the ε-ring rotation around the C6'-C7' bond.

Dietary Lutein and Cognitive Function in Adults: A Meta-Analysis of Randomized Controlled Trials

Emerging literature suggests that dietary lutein may have important functions in cognitive health, but there is not enough data to substantiate its effects in human cognition. The current study was intended to determine the overall effect of lutein on the main domains of cognition in the adult population based on available placebo randomized-controlled trials. Literature searches were conducted in PubMed, AGRICOLA, Scopus, MEDLINE, and EMBASE on 14 November 2020. The effect of lutein on complex attention, executive function and memory domains of cognition were assessed by using an inverse-variance meta-analysis of standardized mean differences (SMD) (Hedge’s g method). Dietary lutein was associated with slight improvements in cognitive performance in complex attention (SMD 0.02, 95% CI −0.27 to 0.31), executive function (SMD 0.13, 95% CI −0.26 to 0.51) and memory (SMD 0.03, 95% CI −0.26 to 0.32), but its effect was not significant. Change-from-baseline analysis revealed that lutein consumption could have a role in maintaining cognitive performance in memory and executive function. Although dietary lutein did not significantly improve cognitive performance, the evidence across multiple studies suggests that lutein may nonetheless prevent cognitive decline, especially executive function. More intervention studies are needed to validate the role of lutein in preventing cognitive decline and in promoting brain health.

Plasma Concentrations and Maternal-Umbilical Cord Plasma Ratios of the Six Most Prevalent Carotenoids across Five Groups of Birth Gestational Age

Carotenoids are antioxidant nutrients with the potential to provide protection against oxidative stress. Plasma carotenoid concentrations are lower in newborn infants compared to their mothers; however, limited information is available regarding how concentrations differ by gestational age. The objective of this research is to assess maternal and umbilical cord plasma carotenoid concentrations and maternal-umbilical cord plasma ratios across five groups of birth gestational age. Mother-infant dyads were enrolled at delivery for collection of maternal and umbilical cord blood. Plasma carotenoids were analyzed by HPLC and LC-MS/MS. Birth gestational age was categorized into five groups, and the Kruskal–Wallis test compared carotenoid concentrations and maternal-umbilical cord plasma ratios between these groups. A p-value of < 0.05 was considered statistically significant. 370 mother-infant dyads were included, with most infants delivered at early term (20.3%) or term (64.6%). Though maternal plasma concentrations increased with birth gestational age, we observed less variability in umbilical cord plasma concentrations, thus the maternal-umbilical cord plasma ratio also increased with birth CGA groups for lutein + zeaxanthin (p = 0.008), β-cryptoxanthin (p = 0.027), α-carotene (p = 0.030); β-carotene approached significance (p = 0.056). Additional research is needed to determine if carotenoid concentrations were physiologic to varying gestational ages or if they were impacted by factors associated with preterm birth.

A Systematic Review of Carotenoids in the Management of Diabetic Retinopathy

Diabetic retinopathy, which was primarily regarded as a microvascular disease, is the leading cause of irreversible blindness worldwide. With obesity at epidemic proportions, diabetes-related ocular problems are exponentially increasing in the developed world. Oxidative stress due to hyperglycemic states and its associated inflammation is one of the pathological mechanisms which leads to depletion of endogenous antioxidants in retina in a diabetic patient. This contributes to a cascade of events that finally leads to retinal neurodegeneration and irreversible vision loss. The xanthophylls lutein and zeaxanthin are known to promote retinal health, improve visual function in retinal diseases such as age-related macular degeneration that has oxidative damage central in its etiopathogenesis. Thus, it can be hypothesized that dietary supplements with xanthophylls that are potent antioxidants may regenerate the compromised antioxidant capacity as a consequence of the diabetic state, therefore ultimately promoting retinal health and visual improvement. We performed a comprehensive literature review of the National Library of Medicine and Web of Science databases, resulting in 341 publications meeting search criteria, of which, 18 were found eligible for inclusion in this review. Lutein and zeaxanthin demonstrated significant protection against capillary cell degeneration and hyperglycemia-induced changes in retinal vasculature. Observational studies indicate that depletion of xanthophyll carotenoids in the macula may represent a novel feature of DR, specifically in patients with type 2 or poorly managed type 1 diabetes. Meanwhile, early interventional trials with dietary carotenoid supplementation show promise in improving their levels in serum and macular pigments concomitant with benefits in visual performance. These findings provide a strong molecular basis and a line of evidence that suggests carotenoid vitamin therapy may offer enhanced neuroprotective effects with therapeutic potential to function as an adjunct nutraceutical strategy for management of diabetic retinopathy.

Early Enteral Feeding in Preterm Infants: A Narrative Review of the Nutritional, Metabolic, and Developmental Benefits

Enteral feeding is the preferred method of nutrient provision for preterm infants. Though parenteral nutrition remains an alternative to provide critical nutrition after preterm delivery, the literature suggests that enteral feeding still confers significant nutritional and non-nutritional benefits. Therefore, the purpose of this narrative review is to summarize health and clinical benefits of early enteral feeding within the first month of life in preterm infants. Likewise, this review also proposes methods to improve enteral delivery in clinical care, including a proposal for decision-making of initiation and advancement of enteral feeding. An extensive literature review assessed enteral studies in preterm infants with subsequent outcomes. The findings support the early initiation and advancement of enteral feeding impact preterm infant health by enhancing micronutrient delivery, promoting intestinal development and maturation, stimulating microbiome development, reducing inflammation, and enhancing brain growth and neurodevelopment. Clinicians must consider these short- and long-term implications when caring for preterm infants.

Potential health benefits of carotenoid lutein: An updated review

Carotenoids in food substances are believed to have health benefits by lowering the risk of diseases. Lutein, a carotenoid compound, is one of the essential nutrients available in green leafy vegetables (kale, broccoli, spinach, lettuce, and peas), along with other foods, such as eggs. As nutrition plays a pivotal role in maintaining human health, lutein, as a nutritional substance, confers promising benefits against numerous health issues, including neurological disorders, eye diseases, skin irritation, etc. This review describes the in-depth health beneficial effects of lutein. As yet, a minimal amount of literature has been undertaken to consider all its promising bioactivities. The step-by-step biosynthesis of lutein has also been taken into account in this review. Besides, this review demonstrates the drug interactions of lutein with β-carotene, as well as safety concerns and dosage. The potential benefits of lutein have been assessed against neurological disorders, eye diseases, cardiac complications, microbial infections, skin irritation, bone decay, etc. Additionally, recent studies ascertained the significance of lutein nanoformulations in the amelioration of eye disorders, which are also considered in this review. Moreover, a possible approach for the use of lutein in bioactive functional foods will be discussed.

Beyond Nutrient Deficiency-Opportunities to Improve Nutritional Status and Promote Health Modernizing DRIs and Supplementation Recommendations

The US Dietary Guidelines for Americans (DGA) provide dietary recommendations to meet nutrient needs, promote health, and prevent disease. Despite 40 years of DGA, the prevalence of under-consumed nutrients continues in the US and globally, although dietary supplement use can help to fill shortfalls. Nutrient recommendations are based on Dietary Reference Intakes (DRIs) to meet the nutrient requirements for nearly all (97 to 98 percent) healthy individuals in a particular life stage and gender group and many need to be updated using current evidence. There is an opportunity to modernize vitamin and mineral intake recommendations based on biomarker or surrogate endpoint levels needed to 'prevent deficiency' with DRIs based on ranges of biomarker or surrogate endpoints levels that support normal cell/organ/tissue function in healthy individuals, and to establish DRIs for bioactive compounds. We recommend vitamin K and Mg DRIs be updated and DRIs be established for lutein and eicosapentaenoic and docosahexaenoic acid (EPA + DHA). With increasing interest in personalized (or precision) nutrition, we propose greater research investment in validating biomarkers and metabolic health measures and the development and use of inexpensive diagnostic devices. Data generated from such approaches will help elucidate optimal nutrient status, provide objective evaluations of an individual's nutritional status, and serve to provide personalized nutrition guidance.

Predictors of macular pigment and contrast threshold in Spanish healthy normolipemic subjects (45-65 years) with habitual food intake

Introduction

The dietary carotenoids lutein (L) and zeaxanthin (Z) are transported in the bloodstream by lipoproteins, sequestered by adipose tissue, and eventually captured in the retina where they constitute macular pigment. There are no L&Z dietary intake recommendations nor desired blood/tissue concentrations for the Spanish general population. Our aim was to assess the correlation of L&Z habitual dietary intake (excluding food supplements), resulting serum concentrations and lipid profile with macular pigment optical density (MPOD) as well as the contrast sensitivity (CT), as visual outcome in normolipemic subjects (n = 101) aged 45–65.

Methods

MPOD was measured by heterochromatic flicker photometry, serum L&Z by HPLC, the dietary intake by a 3-day food records and CT using the CGT-1000-Contrast-Glaretester at six stimulus sizes, with and without glare.

Results

Lutein and zeaxanthin concentrations (median) in serum: 0.361 and 0.078 μmol/L, in dietary intake: 1.1 mg L+Z/day. MPOD: 0.34du. L+Z intake correlates with their serum concentrations (rho = 0.333, p = 0.001), which in turn correlates with MPOD (rho = 0.229, p = 0.000) and with fruit and vegetable consumption (rho = 0.202, p = 0.001), but not with lutein+zeaxanthin dietary intake. MPOD correlated with CT, with and without glare (rho ranges: -0.135, 0.160 and -0.121, –0.205, respectively). MPOD predictors: serum L+Z, L+Z/HDL-cholesterol (β-coeficient: -0.91±0.2, _95%CI: -1.3,-0.5) and HDL-cholesterol (R² = 15.9%). CT predictors: MPOD, mainly at medium and smaller visual angles (corresponding to spatial frequencies for which sensitivity declines with age) and gender (β-coefficients ranges: -0.95,-0.39 and -0.13,-0.39, respectively).

Conclusion

A higher MPOD is associated with a lower ratio of L+Z/HDL-cholesterol and with a lower CT (higher contrast sensitivity). The HDL-cholesterol would also act indirectly on the CT improving the visual function.

Lutein Has a Positive Impact on Brain Health in Healthy Older Adults: A Systematic Review of Randomized Controlled Trials and Cohort Studies

A previous systematic review revealed that lutein intake leads to improved cognitive function among older adults. However, the association between lutein intake and brain health remains unclear. Methods: We searched the Web of Science, PubMed, PsycInfo, and Cochrane Library for research papers. The criteria were (1) an intervention study using oral lutein intake or a cross-sectional study that examined lutein levels and the brain, (2) participants were older adults, and (3) brain activities or structures were measured using a brain imaging technique (magnetic resonance imaging (MRI) or electroencephalography (EEG)). Results: Seven studies using MRI (brain activities during rest, cognitive tasks, and brain structure) and two studies using EEG were included. We mainly focused on MRI studies. Three intervention studies using MRI indicated that 10 mg lutein intake over 12 months had a positive impact on healthy older adults’ brain activities during learning, resting-state connectivity, and gray matter volumes. Four cross-sectional studies using MRI suggested that lutein was positively associated with brain structure and neural efficiency during cognitive tasks. Conclusion: Although only nine studies that used similar datasets were reviewed, this systematic review indicates that lutein has beneficial effects on healthy older adults’ brain health.

Anti-aging effects of a functional food via the action of gut microbiota and metabolites in aging mice

Wushen (WS) is a mixed food containing 55 natural products that is beneficial to human health. This study aimed to reveal the preventive effect of WS on aging via a combined analysis of gut microbiome and metabolome. Senescence-accelerated mouse prone 8 (SAMP8) mice were used as aging model and senescence-accelerated mouse resistant 1 (SAMR1) mice as control. The mice were fed four diet types; control diet (for SAMR1 mice), standard diet (for SAMP8 mice, as SD group), WS diet, and fecal microbiota transplantation (FMT; transplanted from aging-WS mice). Our results showed that the weight, food intake, neurological function, and general physical conditions significantly improved in WS-fed mice compared to those fed with SD. The CA1 hippocampal region in WS-fed aged mice showed fewer shriveled neurons and increased neuronal layers compared to that of the SD group. WS-fed mice showed a decrease in malondialdehyde and an increase in superoxide dismutase levels in the brain; additionally, IL-6 and TNF-α levels significantly decreased, whereas IL-2 levels and the proportion of lymphocytes, CD3+CD8+ T, and CD4+IFNγ+T cells increased in WS-fed mice. After fed with WS, the abundance of Ruminococcus and Butyrivibrio markedly increased, whereas Lachnoclostridium and Ruminiclostridium significantly decreased in the aging mice. In addition, 887 differentially expressed metabolites were identified in fecal samples, among these, Butyrivibrio was positively correlated with D-glucuronic acid and Ruminococcus was positively associated with 5-acetamidovalerate. These findings provide mechanistic insight into the impact of WS on aging, and WS may be a valuable diet for preventing aging.

Cationic liposome-encapsulated carotenoids as a potential treatment for fibromyalgia in an animal model

The present study investigated the efficacy of cationic liposome-encapsulated carotenoids (lutein or beta-carotene) as a treatment in an animal model of fibromyalgia (FM). Preparation and characterization of the nano-sized cationic liposomal carotenoids have been carried out. FM has been induced in the experimental animals via successive subcutaneous reserpine injection (1 mg/kg). Animals were divided into four groups; control, reserpinized (Res), reserpinized and cationic liposomal lutein-treated (Res + CL-Lut), and reserpinized and liposomal beta-carotene-treated (Res + CL-Bc). Levels of norepinephrine (NE), dopamine (DA), and serotonin (5-HT), and oxidative stress markers (MDA, H₂O₂, NO, and GSH) were determined in the brain's cortical tissue of the different groups of animals. Furthermore, the spectral analysis of the electrocorticogram (ECoG) was carried out. Animal behavior was tested for different animal groups. Results showed a significant reduction in monoamines, an elevation of oxidative stress markers, a shift in the ECoG frequency band power, and a change in pain threshold of the reserpinized animals. A return to a non-significant difference from the control values of all the measured parameters has been obtained after two weeks of cationic liposomal carotenoid preparations treatment. The present findings shed more light on the validity of the reserpine model of FM and provide evidence for the antidepressant, antioxidant, and anti-nociceptive potential of the cationic liposomal carotenoids. The present results proofed that the natural product preparations on a nano-sized scale could be a good alternative to the pharmacological interventions for FM treatment.

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.

Multiple Micronutrients, Lutein, and Docosahexaenoic Acid Supplementation during Lactation: A Randomized Controlled Trial

Breastfed infants require an adequate supply of critical nutrients for growth, tissue functions, and health. Recommended intakes for several nutrients are considerably higher in lactating than non-lactating women but are not always met with habitual diets. We report a randomized, double-blind clinical trial in 70 healthy lactating women in Germany evaluating the effects of supplementation with multiple micronutrients, lutein, and docosahexaenoic acid (DHA) compared to placebo on maternal nutrient status and milk composition. The primary endpoint was the effect on the change of human milk DHA content (as a proportion of total milk fatty acids) during 12 weeks of supplementation. Maternal blood and milk biomarkers were measured as secondary endpoints. Supplementation increased maternal milk DHA by 30% compared to a decline in the placebo group. Supplementation also increased maternal blood DHA (17%), eicosapentaenoic acid (4%), 25-OH-vitamin D (24%), vitamin B12 (12%), lutein (4%), and beta carotene (49%), while homocysteine decreased. No significant difference in the number of adverse events was observed between supplementation and placebo groups. In conclusion, multi-micronutrient supplementation was safe and increased maternal blood and milk concentrations of selected nutrients in healthy women.

Development of zeaxanthin-rich tomato fruit through genetic manipulations of carotenoid biosynthesis

The oxygenated carotenoid zeaxanthin provides numerous benefits to human health due to its antioxidant properties. Especially it is linked to protecting, together with the xanthophyll lutein, the retina in the human eye by filtering harmful blue light thus delaying the progression of age-related macular degeneration (AMD), the most prevalent cause of blindness in developed countries. Despite its high nutritional value, zeaxanthin is less available than other substantial carotenoids in our diet. To solve this shortage, we chose to develop a new food source that would contain a high concentration of natural zeaxanthin. Tomato (Solanum lycopersicum L.) was selected as the target plant since it is the second largest vegetable crop grown worldwide and its fruit characteristically synthesizes and accumulates a high concentration of carotenoids. We employed two genetic approaches in order to enhance zeaxanthin biosynthesis in tomato fruit: a transgenic metabolic engineering and classical genetic breeding. A nontransgenic tomato line, named 'Xantomato', was generated whose fruit accumulated zeaxanthin at a concentration of 39 μg/g fresh weight (or 577 μg/g dry weight), which comprised ca. 50% of total fruit carotenoids compared to zero in the wild type. This is the highest concentration of zeaxanthin reached in a primary crop. Xantomato can potentially increase zeaxanthin availability in the human diet and serve as raw material for industrial applications.

Individual differences in visual function

A significant proportion of research on the visual system focuses on general principles that apply to samples and/or populations. Many questions, however, are more suited to the specific characteristics of an individual. The visual system, like most systems of the body, is extremely variable with respect to function and susceptibility to disease. Understanding this variation is an important avenue to better measurement, disease prevention and treatment.

Zeaxanthin and Lutein: Photoprotectors, Anti-Inflammatories, and Brain Food

This review compares and contrasts the role of carotenoids across the taxa of life—with a focus on the xanthophyll zeaxanthin (and its structural isomer lutein) in plants and humans. Xanthophylls’ multiple protective roles are summarized, with attention to the similarities and differences in the roles of zeaxanthin and lutein in plants versus animals, as well as the role of meso-zeaxanthin in humans. Detail is provided on the unique control of zeaxanthin function in photosynthesis, that results in its limited availability in leafy vegetables and the human diet. The question of an optimal dietary antioxidant supply is evaluated in the context of the dual roles of both oxidants and antioxidants, in all vital functions of living organisms, and the profound impact of individual and environmental context.

Anti-Apoptotic Effects of Carotenoids in Neurodegeneration

Apoptosis, programmed cell death type I, is a critical part of neurodegeneration in cerebral ischemia, Parkinson’s, and Alzheimer’s disease. Apoptosis begins with activation of pro-death proteins Bax and Bak, release of cytochrome c and activation of caspases, loss of membrane integrity of intracellular organelles, and ultimately cell death. Approaches that block apoptotic pathways may prevent or delay neurodegenerative processes. Carotenoids are a group of pigments found in fruits, vegetables, and seaweeds that possess antioxidant properties. Over the last several decades, an increasing number of studies have demonstrated a protective role of carotenoids in neurodegenerative disease. In this review, we describe functions of commonly consumed carotenoids including lycopene, β-carotene, lutein, astaxanthin, and fucoxanthin and their roles in neurodegenerative disease models. We also discuss the underlying cellular mechanisms of carotenoid-mediated neuroprotection, including their antioxidant properties, role as signaling molecules, and as gene regulators that alleviate apoptosis-associated brain cell death.

Effects of Lutein and Astaxanthin Intake on the Improvement of Cognitive Functions among Healthy Adults: A Systematic Review of Randomized Controlled Trials

Background: Fruits and vegetables are generally rich in antioxidants such as carotenoids. Consumption of carotenoids is expected to have benefits on cognitive functions in humans. However, previous randomized controlled trials (RCT) using carotenoids have reported inconsistent results. Therefore, this systematic review (SR) aimed to summarize the effect of carotenoid intake on cognitive functions in humans. Method: PubMed, Cochrane Library, Web of Science, and PsychoINFO were searched for research papers on carotenoid intake with the criteria that 1) oral carotenoid intake was evaluated using RCTs, 2) participants were healthy young, middle-aged, or older, and 3) cognitive functions were measured using RCTs. Results: Five studies using lutein and two studies using astaxanthin met the inclusion criteria. Consumption of lutein and its isomer showed consistent results in selective improvement of visual episodic memory in young and middle-aged adults while inhibition was observed in middle-aged and older adults. One of the two included astaxanthin studies reported a significant improvement of verbal episodic memory performance in middle-aged adults. Conclusion: This SR showed that the 10 mg lutein per day for twelve months can lead to improvement of cognitive functions. Due to the small number of studies, it is difficult to conclude whether astaxanthin would have a positive effect on cognitive functions.

The macular carotenoids: A biochemical overview

Among the more than 750 carotenoids identified in nature, only lutein, zeaxanthin, meso-zeaxanthin, and their oxidative metabolites are selectively accumulated in the macula lutea region of the human retina. These retinal carotenoids are collectively referred to as the macular pigment (MP) and are obtained only through dietary sources such as green leafy vegetables and yellow and orange fruits and vegetables. Lutein- and zeaxanthin-specific binding proteins (StARD3 and GSTP1, respectively) mediate the highly selective uptake of MP into the retina. Meso-zeaxanthin is rarely present in the diet, and its unique presence in the human eye results from metabolic conversion from dietary lutein by the RPE65 enzyme. The MP carotenoids filter high-intensity, short-wavelength visible light and are powerful antioxidants in a region vulnerable to light-induced oxidative stress. This review focuses on MP chemistry, absorption, metabolism, transport, and distribution with special emphasis on animal models used for MP study. This article is part of a Special Issue entitled Carotenoids recent advances in cell and molecular biology edited by Johannes von Lintig and Loredana Quadro.