Low macular pigment optical density is associated with lower cognitive performance in a large, population-based sample of older adults

Effects of fruit and vegetable intake on memory and attention: a systematic review of randomized controlled trials

BACKGROUND

Memory and attention are important for daily functioning, and their function deteriorates due to aging. However, fruit and vegetable consumption are one of the protective factors against deterioration in memory and attention. This systematic review of randomized controlled trials (RCTs) aims to identify the effects of fruit and vegetable consumption on memory and attention.

METHODS

We conducted a systematic search in EBSCOhost, ProQuest, PubMed, Embase, and Web of Science from inception up to 06/09/2022. The inclusion criteria were peer-reviewed articles, fruit and vegetable intake measured using randomized controlled trials, and the outcome measures that showed the results of memory and attention scores. Two researchers independently extracted articles that met the selection criteria and evaluated the quality of each study.

RESULTS

There were 70 articles identified from the databases, of which 13 articles met the inclusion criteria and were included in this systematic review. There were 493 participants in total. The results show that consumption of fruit and vegetable intake improved memory and attention in longitudinal studies (10 to 12 weeks). Children showed improvement in immediate recall after supplementation with blueberries. Older adults required a higher dose of fruit and vegetable intake consumption to achieve significant improvement compared with children and younger adults. Furthermore, the effect of fruits and vegetables on memory showed better immediate memory recall than delayed recall.

CONCLUSION

This systematic review showed that there is an improvement in memory and attention with fruit and vegetable intake consumption. Hence, awareness of fruit and vegetable intake consumption is important to maintain cognitive health.

Aging and antioxidants: the impact of dietary carotenoid intakes on soluble klotho levels in aged adults

Objectives

The association between dietary carotenoid intake and Soluble Klotho (S-Klotho) levels among the elderly population requires further evaluation. The purpose of this study is to evaluate the relationship between the dietary carotenoid intake and the S-Klotho plasma levels in older adults.

Methods

Eligible participants aged 60 years or above were selected from the National Health and Nutrition Examination Surveys (NHANES) data, collected between 2007 and 2016. The consumption of carotenoids was determined through two 24-hour dietary recall assessments. Moreover, the S-Klotho levels in the serum were measured using an Enzyme-Linked Immuno-Sorbent Assay (ELISA).

Results

A total of 5,056 participants were included in the study having a median total carotenoid intake of 9775.25 μg (95% confidence interval (CI): 8971.30-10579.21) and a median S-Klotho concentration of 815.59 pg/mL (95% CI: 802.59-828.60). The multivariable regression analysis showed that a single standard deviation increase in total carotenoid intake was significantly associated with an 8.40 pg/mL increase in S-Klotho levels (95% CI: 0.48-16.31). When the carotenoids were divided into quartiles, participants in the third ((4963.5μg/day,11662.5μg/day]) and fourth quartiles ((11662.5μg/day,377178μg/day]) showed higher S-Klotho levels compared to those in the first quartile. Among carotenoid subtypes, increased intake of α-carotene, β-carotene, and lutein with zeaxanthin was associated with elevated S-Klotho levels. These observed associations between carotenoid subtypes and S-Klotho levels remained consistent across male participants, having a normal weight, and a moderate physical activity based on stratified analysis.

Conclusion

The total carotenoid intake was positively related to plasma levels of S-Klotho in the elderly population, particularly for α-carotene, β-carotene, and lutein with zeaxanthin. However, further research is needed to confirm these findings and explore the underlying mechanisms behind this relationship.

Low Xanthophylls, Retinol, Lycopene, and Tocopherols in Grey and White Matter of Brains with Alzheimer's Disease

BACKGROUND

Oxidative stress contributes to pathogenesis and progression of Alzheimer's disease (AD). Higher levels of the dietary antioxidants- carotenoids and tocopherols- are associated with better cognitive functions and lower risk for AD, and lower levels of multiple carotenoids are found in serum and plasma of patients with AD. Although brains donated by individuals with mild cognitive impairment had significantly lower levels of lutein and beta-carotene, previous investigators found no significant difference in carotenoid levels of brains with AD and cognitively normal brains.

OBJECTIVE

This study tested the hypothesis that micronutrients are significantly lower in donor brains with AD than in healthy elderly brains.

METHODS

Samples of donor brains with confirmed AD or verified health were dissected into grey and white matter, extracted with organic solvents and analyzed by HPLC.

RESULTS

AD brains had significantly lower levels of lutein, zeaxanthin, anhydrolutein, retinol, lycopene, and alpha-tocopherol, and significantly increased levels of XMiAD, an unidentified xanthophyll metabolite. No meso-zeaxanthin was detected. The overlapping protective roles of xanthophylls, carotenes, α- and γ-tocopherol are discussed.

CONCLUSION

Brains with AD had substantially lower concentrations of some, but not all, xanthophylls, carotenes, and tocopherols, and several-fold higher concentrations of an unidentified xanthophyll metabolite increased in AD (XMiAD).

A Systematic Review of Dietary Supplements in Alzheimer's Disease

Alzheimer's is the most common neurodegenerative disease among the aging population, which has been a major global challenge. The pathogenesis of the disease is still undetermined but postulated to be involved in various mechanisms including oxidative stress, excitotoxicity, inflammation, cell death, genetic factors, protein accumulation, and degradation. There are few Food and Drug Administration (FDA)-approved drugs available for the treatment of Alzheimer's disease (AD) that have limited benefits along with associated adverse effects. A retrospective review of randomized double-blind controlled trials of various supplements used in AD patients was performed on a PubMed search from January 1983 to March 2022. We found 10 articles that have shown positive outcomes in various cognitive domains. We conclude that there should be a global standard to endorse the quality and safety of these supplements.

Supplementation With Carotenoids, Omega-3 Fatty Acids, and Vitamin E Has a Positive Effect on the Symptoms and Progression of Alzheimer’s Disease

Background: Preliminary work by our center has reported behavior and functional benefits in patients with Alzheimer’s disease (AD) following targeted micronutritional supplementation. Objective: To build on the existing exploratory research and investigate the impact of these micronutrients on the natural progression of AD in a randomized controlled trial. Methods: Patients with mild-moderate AD consumed daily 1 g fish oil (of which 500 mg DHA, 150 mg EPA), 22 mg carotenoids (10 mg lutein, 10 mg meso-zeaxanthin, 2 mg zeaxanthin), and 15 mg vitamin E or placebo for 12 months in a double-blind, placebo-controlled, randomized clinical trial. Carotenoids, ω-3FAs, and vitamin E were quantified in blood. Carotenoids were also measured in skin. AD severity was measured using the mini-mental state examination and dementia severity rating scale tools. Behavior, mood, and memory were measured using an informant-based questionnaire. Results: Following 12 months of supplementation, the active group (n = 50) compared to the placebo group (n = 27), demonstrated statistically significant improvements in skin carotenoid measurements, blood carotenoids, ω-3FAs, and vitamin E concentrations (p <  0.05, for all). The active group also performed better in objective measures of AD severity (i.e., memory and mood), with a statistically significant difference reported in the clinical collateral for memory (p <  0.001). Conclusion: Exponential increases in the prevalence of AD and its relentless progressive nature is driving the need for interventions that help to ameliorate symptoms and improve quality of life in AD patients. Given the positive outcomes demonstrated in this trial, this combined micronutrient dietary supplement should be considered in the overall management of AD.

Carotenoids improve the development of cerebral cortical networks in formula-fed infant macaques

Nutrition during the first years of life has a significant impact on brain development. This study characterized differences in brain maturation from birth to 6 months of life in infant macaques fed formulas differing in content of lutein, β-carotene, and other carotenoids using Magnetic Resonance Imaging to measure functional connectivity. We observed differences in functional connectivity based on the interaction of diet, age and brain networks. Post hoc analysis revealed significant diet-specific differences between insular-opercular and somatomotor networks at 2 months of age, dorsal attention and somatomotor at 4 months of age, and within somatomotor and between somatomotor-visual and auditory-dorsal attention networks at 6 months of age. Overall, we found a larger divergence in connectivity from the breastfeeding group in infant macaques fed formula containing no supplemental carotenoids in comparison to those fed formula supplemented with carotenoids. These findings suggest that carotenoid formula supplementation influences functional brain development.

Early Childhood Lutein and Zeaxanthin Intake Is Positively Associated with Early Childhood Receptive Vocabulary and Mid-Childhood Executive Function But No Other Cognitive or Behavioral Outcomes in Project Viva

BACKGROUND

Lutein and zeaxanthin are carotenoids associated with better cognition in older adults. Recent evidence suggests that their dietary intake may also have cognitive implications in childhood.

OBJECTIVE

The aim was to examine associations of early childhood lutein and zeaxanthin (L/Z) intake with cognition in early and mid-childhood.

METHODS

Among 1378 children in Project Viva, a prospective cohort, mothers reported their child's dietary intake in early childhood (median: 3.2 y) using a food-frequency questionnaire. Child cognition and behavior were assessed at the same time point using the Peabody Picture Vocabulary Test (PPVT-III) and the Wide Range Assessment of Visual Motor Abilities (WRAVMA) and at mid-childhood (median: 7.7 y) using the Kaufman Brief Intelligence Test, the WRAVMA drawing subtest, the Wide Range Assessment of Memory and Learning, the Behavior Rating Inventory of Executive Function (BRIEF), and the Strengths and Difficulties Questionnaire.

RESULTS

Children consumed a daily mean (SD) of 1.0 (0.4) mg L/Z in early childhood. Children in the third-quartile category of L/Z intake had a mean PPVT-III score 2.40 (95% CI: 0.27, 4.53) points higher than children in the lowest quartile category in early childhood, suggesting better receptive vocabulary. Children in the highest quartile category of L/Z intake had a parent-reported mean BRIEF Global Executive Composite score 1.65 (95% CI: -3.27, -0.03) points lower than children in the lowest quartile category in mid-childhood, indicating better executive function. We did not observe associations between L/Z intake and any of the other cognitive or behavioral outcomes assessed.

CONCLUSIONS

The overall findings do not provide strong evidence of an association between child L/Z intake and cognition and behavior. However, the positive associations found between early childhood L/Z intake and early childhood receptive vocabulary and mid-childhood executive function, in addition to previous evidence of neurodevelopmental benefit of L/Z intake, suggest that this relation deserves further investigation.

Effect of macular pigment carotenoids on cognitive functions: A systematic review

Lutein and zeaxanthin-xanthophyll carotenoids with antioxidant and anti-inflammatory characteristics-are present in the retina and the brain. High concentrations of these carotenoids have been positively related to cognitive performance. Therefore, this systematic review analyses the relationship between macular pigment density and cognitive functions. Most relevant databases were scoured for studies on healthy people relating cognitive functions to macular pigment optical density (MPOD). There were no age, sex, or race limitations. PROSPERO registration: CRD42021254833. Nineteen studies were included, seven randomized controlled trials (RCT) and eleven observational studies. The general aim of the studies was to examine the association between carotenoids (lutein, meso‑zeaxanthin and zeaxanthin) and cognitive function. Most observational studies correlates MPOD levels with cognitive function or brain activity. Besides, RCTs compared the cognitive function and/or brain activity after increasing lutein and zeaxanthin intake though dietary supplementation or avocado consumption. Dietary lutein and zeaxanthin intake increased MPOD in six of the seven clinical trials and significantly improved most of the cognitive functions studied. A wide variety of test and methodologies for measuring cognitive functions were observed. Memory, processing speed, attention and reasoning were the cognitive function significantly related to MPOD levels in adults. Brain activity also was related to MPOD, but the results were inconsistent. Only four of the eleven observational studies were based on young people and all studies showed a significant relationship between MPOD and cognitive functions. This systematic review showed a direct relationship among cognitive functions, macular pigment and the intake of lutein and zeaxanthin.

Can Diet Supplements of Macular Pigment of Lutein, Zeaxanthin, and Meso-zeaxanthin Affect Cognition?

Background: Lutein (L), zeaxanthin (Z), and meso-zeaxanthin (MZ) are collectively called macular pigment. MZ can be converted from L in the macula. In the recent decade, many studies have been performed to investigate the effects for taking carotenoids, especially L and Z or L, Z, and MZ, as diet supplements on human health. Objective: We examined if diet supplements of L + Z or L + Z + MZ have effects on cognitive function in adults. Methods: A systemic literature search was performed in March 2021 with the following keywords: lutein, zeaxanthin, meso-zeaxanthin, cognition, cognitive, and macular pigment. The searched databases included Medline EBSCOhost, Scopus, Elsevier, Cochrane Library, ProQuest, and ClinicalTrials.gov. Findings from eight clinical trials were presented as the strongest evidence on the studied topic. Results: Most studies have found that macular pigments (L + Z) in blood or macula are positively correlated with cognitive performance. As an index of the amount of macular pigments in the brain, macular pigment optical density is related to cognitive performance in adults. In addition, there is an inverse relationship between a higher amount of macular pigment in the blood and lower risk of mild cognitive impairments or Alzheimer’s disease. Based on the findings from the clinical trials, diet supplements of L + Z or L + Z + MZ are associated with improved cognition in adults. Conclusion: The diet supplements of L + Z or L + Z+MZ are associated with better cognitive functioning, which may be via their beneficial effects on the vision.

Vision impairment and cognitive decline among older adults: a systematic review

OBJECTIVES

There has been increasing epidemiological research examining the association between vision impairment (VI) and cognitive impairment and how poor vision may be a modifiable risk factor for cognitive decline. The objective of this systematic review is to synthesise the published literature on the association of VI with cognitive decline, cognitive impairment or dementia, to aid the development of interventions and guide public policies pertaining to the relationship between vision and cognition.

METHODS

A literature search was performed with Embase, Medline and Cochrane library databases from inception to March 2020, and included abstracts and articles published in peer-reviewed journals in English. Our inclusion criteria included publications that contained subjective/objective measures of vision and cognition, or a diagnosis of VI, cognitive impairment or dementia. Longitudinal or cross-sectional studies with ≥100 participants aged >50 years were included. The search identified 11 805 articles whose abstracts underwent screening by three teams of study authors. Data abstraction and quality assessment using the Effective Public Health Practice Project Quality Assessment Tool were performed by one author (NN). 10% of the articles underwent abstraction and appraisal by a second author (LA/VV), results were compared between both and were in agreement.

RESULTS

110 full-text articles were selected for data extraction, of which 53 were cross-sectional, 43 longitudinal and 14 were case-control studies. The mean age of participants was 73.0 years (range 50-93.1). Ninety-one (83%) of these studies reported that VI was associated with cognitive impairment.

CONCLUSION

Our systematic review indicates that a majority of studies examining the vision-cognition relationship report that VI is associated with more cognitive decline, cognitive impairment or dementia among older adults. This synthesis supports the need for additional research to understand the mechanisms underlying the association between VI and cognitive impairment and to test interventions that mitigate the cognitive consequences of VI.

Omega-3 fatty acid, carotenoid and vitamin E supplementation improves working memory in older adults: A randomised clinical trial

BACKGROUND & AIMS

Accumulating evidence suggests that omega-3 fatty acids (ω-3FAs), carotenoids and vitamin E can improve cognitive performance. However, their collective impact on cognition has not yet been investigated in healthy individuals. This study investigated the combined effect of ω-3FA, carotenoid and vitamin E supplementation on the cognitive performance of older adults.

METHODS

Cognitively healthy individuals aged ≥65 years consumed daily 1 g fish oil (of which 430 mg docosahexaenoic acid, 90 mg eicosapentaenoic acid), 22 mg carotenoids (10 mg lutein, 10 mg meso-zeaxanthin, 2 mg zeaxanthin) and 15 mg vitamin E or placebo for 24 months in a double-blind, placebo-controlled, randomised clinical trial.

RESULTS

Following 24-month supplementation, individuals in the active group (n = 30; aged 69.03 ± 4.41 years; 56.7% female) recorded significantly fewer errors in working memory tasks than individuals receiving placebo (n = 30; aged 69.77 ± 3.74 years; 70% female) (point estimate effect sizes ranged 0.090-0.105). Interestingly, as the cognitive load of the working memory tasks increased, the active group outperformed the placebo group. Statistically significant improvements in tissue carotenoid concentrations, serum xanthophyll carotenoid concentrations and plasma ω-3FA concentrations were also observed in the active group versus placebo (point estimate effect sizes ranged 0.078-0.589). Moreover, the magnitude of change of carotenoid concentrations in tissue, and ω-3FA and carotenoid concentrations in blood were related to the magnitude of change in working memory performance.

CONCLUSION

These results support a biologically plausible rationale whereby these nutrients work synergistically, and in a dose-dependent manner, to improve working memory in cognitively healthy older adults. Increasing nutritional intake of carotenoids and ω-3FAs may prove beneficial in reducing cognitive decline and dementia risk in later life.

STUDY ID NUMBER

ISRCTN10431469; https://doi.org/10.1186/ISRCTN10431469.

Biochemical and Immunological implications of Lutein and Zeaxanthin

Throughout history, nature has been acknowledged for being a primordial source of various bioactive molecules in which human macular carotenoids are gaining significant attention. Among 750 natural carotenoids, lutein, zeaxanthin and their oxidative metabolites are selectively accumulated in the macular region of living beings. Due to their vast applications in food, feed, pharmaceutical and nutraceuticals industries, the global market of lutein and zeaxanthin is continuously expanding but chemical synthesis, extraction and purification of these compounds from their natural repertoire e.g., plants, is somewhat costly and technically challenging. In this regard microbial as well as microalgal carotenoids are considered as an attractive alternative to aforementioned challenges. Through the techniques of genetic engineering and gene-editing tools like CRISPR/Cas9, the overproduction of lutein and zeaxanthin in microorganisms can be achieved but the commercial scale applications of such procedures needs to be done. Moreover, these carotenoids are highly unstable and susceptible to thermal and oxidative degradation. Therefore, esterification of these xanthophylls and microencapsulation with appropriate wall materials can increase their shelf-life and enhance their application in food industry. With their potent antioxidant activities, these carotenoids are emerging as molecules of vital importance in chronic degenerative, malignancies and antiviral diseases. Therefore, more research needs to be done to further expand the applications of lutein and zeaxanthin.

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.

Night Vision and Carotenoids (NVC): A Randomized Placebo Controlled Clinical Trial on Effects of Carotenoid Supplementation on Night Vision in Older Adults

Twilight and low luminance levels are visually challenging environments for the elderly, especially when driving at night. Carotenoid rich diets are known to increase macular pigment optical density (MPOD), which in turn leads to an improvement in visual function. It is not known whether augmenting MPOD can lead to a decrease in vision related night driving difficulties. Additionally, it is unknown if carotenoid supplementation provides additional measurable benefits to one's useful field of view (UFOV) along with a decreased composite crash risk score. The aim of the study was to evaluate changes in night vision function and UFOV in individuals that took carotenoid vitamin supplements for a six-month period compared to a placebo group.

METHODS

A prospective, randomized, double-blind, six-month trial of a 14 mg zeaxanthin/7 mg lutein-based supplement was carried out. Participants were randomized into active or placebo group (approx 2:1).

RESULTS

n = 33 participants (26 males/7 females) participated with 93% capsule intake compliance in the supplemented group (n = 24) and placebo group (n = 9). MPOD (mean/standard error SE) in the active group increased in the Right eye from 0.35 density units (du)/0.04 SE to 0.41 du/0.05 SE; p < 0.001 and in the Left eye from 0.35 du/0.05 SE to 0.37 du, p > 0.05). The supplemented group showed significant improvements in contrast sensitivity with glare in both eyes with improvements in LogMAR scores of 0.147 and 0.149, respectively (p = 0.02 and 0.01, respectively), monocularly tested glare recovery time improved 2.76 and 2.54 s, respectively, (p = 0.008 and p = 0.02), and we also noted a decreased preferred luminance required to complete visual tasks (p = 0.02 and 0.03). Improvements in UFOV scores of divided attention (p < 0.001) and improved composite crash risk score (p = 0.004) were seen in the supplemented group. The placebo group remained unchanged.

CONCLUSIONS

The NVC demonstrates that augmenting MPOD in individuals with difficulty in night vision showed measurable benefits in numerous visual functions that are important for night vision driving in this small sample RCT. Additionally, we observed an improvement in UFOV divided attention test scores and decreased composite risk scores.

Carotenoid-Rich Brain Nutrient Pattern Is Positively Correlated With Higher Cognition and Lower Depression in the Oldest Old With No Dementia

Background: Healthy dietary patterns are related to better cognitive health in aging populations. While levels of individual nutrients in neural tissues are individually associated with cognitive function, the investigation of nutrient patterns in human brain tissue has not been conducted. Methods: Brain tissues were acquired from frontal and temporal cortices of 47 centenarians from the Georgia Centenarian Study. Fat-soluble nutrients (carotenoids, vitamins A, E, K, and fatty acids [FA]) were measured and averaged from the two brain regions. Nutrient patterns were constructed using principal component analysis. Cognitive composite scores were constructed from cognitive assessment from the time point closest to death. Dementia status was rated by Global Deterioration Scale (GDS). Pearson's correlation coefficients between NP scores and cognitive composite scores were calculated controlling for sex, education, hypertension, diabetes, and APOE ε4 allele. Result: Among non-demented subjects (GDS = 1-3, n = 23), a nutrient pattern higher in carotenoids was consistently associated with better performance on global cognition (r = 0.38, p = 0.070), memory (r = 0.38, p = 0.073), language (r = 0.42, p = 0.046), and lower depression (r = -0.40, p = 0.090). The findings were confirmed with univariate analysis. Conclusion: Both multivariate and univariate analyses demonstrate that brain nutrient pattern explained mainly by carotenoid concentrations is correlated with cognitive function among subjects who had no dementia. Investigation of their synergistic roles on the prevention of age-related cognitive impairment remains to be performed.

Carotenoids in Milk and the Potential for Dairy Based Functional Foods

Carotenoids are a family of over 1100 known natural pigments synthesized by plants, algae, fungi and bacteria. Dietary intake of carotenoids is necessary for mammals as they cannot be synthesized in the body. In cows, the nature of the diet consumed strongly influences the composition of milk produced and this includes carotenoid concentration and profile. Fresh forage is the richest source of carotenoids for cows. The main carotenoids identified in forages are lutein, β-carotene, zeaxanthin and epilutein. Manipulating cow feed via carotenoid supplementation increases the carotenoid content of bovine milk. In humans, carotenoids have anti-oxidant, anti-inflammatory and provitamin A activity. Lutein is a major carotenoid in human milk and the brain tissue of adults and infants. Lutein and zeaxanthin are linked to improved eye health and cognitive function. Traditionally for humans, fruit and vegetables have been the main source of carotenoid intake. Functional foods present an opportunity to incorporate these naturally occurring compounds into milk products for added health benefits, widening the range of dietary sources of carotenoids. We offer an overview of the literature to date on carotenoid-fortified dairy products and infant formula. This review will describe and summarize the key mechanisms by which the carotenoid profile of bovine milk can be manipulated. We present findings on the origin and role of carotenoids in bovine and human milk, outline factors that impact the carotenoid content of milk, evaluate carotenoid-fortified milk products and discuss the associated challenges, such as bioaccessibility and stability.

Nutritional cognitive neuroscience of aging: Focus on carotenoids and cognitive frailty

The term „nutritional cognitive neuroscience” was recently established to define a research field focusing on the impact of nutrition on cognition and brain health across the life span. In this overview, we summarize the robust evidence on the role of carotenoids as micronutrients with different biological properties in persons with cognitive (pre)frailty. As neurodegenerative processes during aging occur in a continuum from brain aging to dementia, we propose the name „nutritional cognitive neuroscience of aging“ to define research on the role of nutrition and micronutrients in cognitive frailty. Further studies are warranted which integrate carotenoid interventions in multidomain, personalized lifestyle strategies.

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Cognitive integrity is an essential element of healthy and active ageing.

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Oxidative distress is strongly linked to neurodegeneration.

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Consumption and levels of carotenoids are linked to cognitive frailty.

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There is conflict of evidence for intervention trials with carotenoids in dementia.

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Future studies with carotenoids should be within personalized and multidomain strategies.

The effects of lutein and zeaxanthin on resting state functional connectivity in older Caucasian adults: a randomized controlled trial

The carotenoids lutein (L) and zeaxanthin (Z) accumulate in retinal regions of the eye and have long been shown to benefit visual health. A growing literature suggests cognitive benefits as well, particularly in older adults. The present randomized controlled trial sought to investigate the effects of L and Z on brain function using resting state functional magnetic resonance imaging (fMRI). It was hypothesized that L and Z supplementation would (1) improve intra-network integrity of default mode network (DMN) and (2) reduce inter-network connectivity between DMN and other resting state networks. 48 community-dwelling older adults (mean age = 72 years) were randomly assigned to receive a daily L (10 mg) and Z (2 mg) supplement or a placebo for 1 year. Resting state fMRI data were acquired at baseline and post-intervention. A dictionary learning and sparse coding computational framework, based on machine learning principles, was used to investigate intervention-related changes in functional connectivity. DMN integrity was evaluated by calculating spatial overlap rate with a well-established DMN template provided in the neuroscience literature. Inter-network connectivity was evaluated via time series correlations between DMN and nine other resting state networks. Contrary to expectation, results indicated that L and Z significantly increased rather than decreased inter-network connectivity (Cohen's d = 0.89). A significant intra-network effect on DMN integrity was not observed. Rather than restoring what has been described in the available literature as a "youth-like" pattern of intrinsic brain activity, L and Z may facilitate the aging brain's capacity for compensation by enhancing integration between networks that tend to be functionally segregated earlier in the lifespan.

Maternal Intake of Lutein and Zeaxanthin during Pregnancy Is Positively Associated with Offspring Verbal Intelligence and Behavior Regulation in Mid-Childhood in the Project Viva Cohort

BACKGROUND

Lutein and zeaxanthin are carotenoids associated with better cognition at older age. To our knowledge, no previous study has evaluated their cognitive implications in the prenatal period, when the brain undergoes its most rapid development.

OBJECTIVE

The objective of this study was to examine associations of maternal lutein and zeaxanthin (L/Z) intake during pregnancy with child cognition.

DESIGN

Among 1580 mother-child pairs in Project Viva, a prospective cohort, we assessed maternal intake of L/Z during pregnancy using food frequency questionnaires and offspring cognition by the Visual Recognition Memory paradigm in infancy, the Peabody Picture Vocabulary Test and the Wide Range Assessment of Visual Motor Abilities (WRAVMA) in early childhood, and the Kaufman Brief Intelligence Test (KBIT-II), the WRAVMA drawing subtest, and the Wide Range Assessment of Memory and Learning in mid-childhood. Parents completed the Behavior Rating Inventory of Executive Function (BRIEF) and Strengths and Difficulties Questionnaire.

RESULTS

Mothers consumed a daily mean (SD) of 2.6 (2.0) mg L/Z in the first and second trimesters of pregnancy. Mean mid-childhood KBIT-II verbal scores were higher with greater maternal L/Z intake [difference of Q4-Q1 means for first trimester: 2.67 (95% CI: 0.13, 5.20) and for second trimester: 3.55 (95% CI: 0.81, 6.28)], indicating better verbal intelligence. Secondary analyses on cognitive subtests showed that mean mid-childhood BRIEF Behavioral Regulation Index scores were lower with greater maternal L/Z intake [difference of Q4-Q1 means for first trimester: -1.63 (95% CI: -3.22, -0.04) and for second trimester: -1.89 (95% CI: -3.58, -0.21)], indicating better behavior regulation ability.

CONCLUSIONS

Higher maternal L/Z intake during pregnancy was associated with better offspring verbal intelligence and behavior regulation ability in mid-childhood, suggesting a potential benefit during prenatal development. We did not find a benefit of higher maternal L/Z intake on other child cognitive or behavioral outcomes. Project Viva is registered at clinicaltrials.gov as NCT02820402.

Carotenoids and Cognitive Outcomes: A Meta-Analysis of Randomized Intervention Trials

Recent evidence suggests that diet can modify the risk of future cognitive impairment and dementia. A biologically plausible rationale and initial clinical data indicate that the antioxidant activities of dietary carotenoids may assist the preservation of cognitive function. A meta-analysis of randomized controlled trials was conducted to examine the relationship between carotenoid supplementation and cognitive performance. A literature search was conducted in the MEDLINE (via PubMed), Scopus, Web of Science, and Cochrane databases from their inception to July 2020. A total of 435 studies were retrieved. Abstract screening using predefined inclusion and exclusion criteria was followed by full-text screening and data extraction of study characteristics and measured outcomes. A meta-analysis of eligible trials was performed using a random-effects model to estimate pooled effect size. We identified 9 studies with a total of 4402 nondemented subjects, whose age ranged from 45 to 78 years. Results of the pooled meta-analysis found a significant effect of carotenoid intervention on cognitive outcomes (Hedge’s g = 0.14; 95% confidence interval: 0.08, 0.20, p < 0.0001). There was no evidence of heterogeneity among the studies (τ2 = 0.00, I² = 0.00%, H² = 1.00) or publication bias. Although further studies are needed, our results suggest that carotenoid interventions are associated with better cognitive performance. Thus, these dietary compounds may help to reduce the risk of cognitive impairment and dementia.

Developing retinal biomarkers for the earliest stages of Alzheimer's disease: What we know, what we don't, and how to move forward

The last decade has seen a substantial increase in research focused on the identification, development, and validation of diagnostic and prognostic retinal biomarkers for Alzheimer's disease (AD). Sensitive retinal biomarkers may be advantageous because they are cost and time efficient, non-invasive, and present a minimal degree of patient risk and a high degree of accessibility. Much of the work in this area thus far has focused on distinguishing between symptomatic AD and/or mild cognitive impairment (MCI) and cognitively normal older adults. Minimal work has been done on the detection of preclinical AD, the earliest stage of AD pathogenesis characterized by the accumulation of cerebral amyloid absent clinical symptoms of MCI or dementia. The following review examines retinal structural changes, proteinopathies, and vascular alterations that have been proposed as potential AD biomarkers, with a focus on studies examining the earliest stages of disease pathogenesis. In addition, we present recommendations for future research to move beyond the discovery phase and toward validation of AD risk biomarkers that could potentially be used as a first step in a multistep screening process for AD risk detection.

The Association Between Hair Cortisol, Hair Cortisone, and Cognitive Function in a Population-Based Cohort of Older Adults: Results From The Irish Longitudinal Study on Ageing

Experimental evidence to date largely supports an association between the stress hormone cortisol and cognitive performance. Older adults, in particular, may be vulnerable to the neurotoxic effects of prolonged increases in cortisol; however, the assessment of chronic hormone levels has previously been challenging. Hair cortisol analysis has advantages over other cortisol metrics for this purpose as it facilitates the assessment of total hormone secretion over several months. Cortisol and cortisone were measured in the scalp hair of 1,876 older adults from The Irish Longitudinal Study on Ageing. Participants underwent a battery of cognitive tests assessing global function, memory, executive function, and processing speed. After adjustment for hair characteristics, demographics, metabolic risk factors, cardiovascular conditions, and depression, regression analysis revealed an inverse relationship of hair glucocorticoids to immediate (cortisol: β = -.12, p = .032; cortisone: β = -.021, p = .036) and delayed (cortisol: β = -.13, p = .003; cortisone: β = -.23, p = .006) word recall performance. They were also associated with more errors on the Mini-Mental State Examination (cortisol: incidence rate ratio (IRR) = 1.06, p = .008; cortisone: IRR = 1.14, p = .002) and Montreal Cognitive Assessment (cortisone: IRR = 1.06, p = .015). Higher hair glucocorticoids are inversely associated with memory and global cognition in a population-based sample of older adults. Future work should explore the prognostic significance of these findings.

The outer influences the inner: Postharvest UV-B irradiation modulates peach flesh metabolome although shielded by the skin

UV-B-driven modulation of secondary metabolism in peach fruit by enhancing the biosynthesis of specific phenolic subclasses, is attracting interest among consumers. However, current literature explored the UV-B-induced metabolic changes only in peach skin subjected to direct UV-B irradiation. Accordingly, this study aimed to understand whether UV-B radiation penetrates the fruit skin and is able to induce metabolic changes also within the inner flesh. Peaches were UV-B-irradiated either 10 or 60 min, and the flesh was sampled after 24 and 36 h. Non-targeted metabolomics revealed that UV-B has a strong impact on peach flesh metabolome, determining an initial decrease after 24 h, followed by an overall increase after 36 h, particularly for terpenoids, phenylpropanoids, phytoalexins and fatty acids in the 60 min UV-B-treated samples (+150.02, +99.14, +43.79 and +25.44 log₂FC, respectively). Transmittance analysis indicated that UV-B radiation does not penetrate below the skin, suggesting a possible signalling pathway between tissues.

Ginger and avocado as nutraceuticals for obesity and its comorbidities

Obesity is a worldwide epidemic and is one of the factors involved in the etiology of type 2 diabetes mellitus. Obesity induces low-grade inflammation and oxidative stress. The treatment for obesity involves changes in diet, physical activity, and even medication and surgery. Currently, the use of nutraceutical compounds is associated with health benefits. Ginger and avocado are used for many people all around the world; however, its effect as a nutraceutical compound is less known by the general population. For this reason, we searched information of the literature to point its effects on distinct mechanisms of defense against the obesity its comorbidities. The present review aimed showing that these nutraceuticals may be useful in obesity treatment. Reports have shown that ginger and avocado induce antioxidant and anti-inflammatory effects by improving enzymatic activity and modulating obesity-related impairments in the anti-inflammatory system in different tissues, without side effects. Furthermore, ginger and avocado were found to be effective in reversing the harmful effects of obesity on blood lipids. In conclusion, on the basis of the positive effects of ginger and avocado in in vitro, animal, and human studies, these nutraceuticals may be useful in obesity treatment.

Bilingualism and Processing Speed in Typically Developing Children and Children With Developmental Language Disorder

Purpose The aim of the current study was to investigate whether dual language experience modulates processing speed in typically developing (TD) children and in children with developmental language disorder (DLD). We also examined whether processing speed predicted vocabulary and sentence-level abilities in receptive and expressive modalities. Method We examined processing speed in monolingual and bilingual school-age children (ages 8-12 years) with and without DLD. TD children (35 monolinguals, 24 bilinguals) and children with DLD (17 monolinguals, 10 bilinguals) completed a visual choice reaction time task. The Clinical Evaluation of Language Fundamentals, the Peabody Picture Vocabulary Test, and the Expressive Vocabulary Test were used as language measures. Results The children with DLD exhibited slower response times relative to TD children. Response time was not modified by bilingual experience, neither in children with typical development nor children with DLD. Also, we found that faster processing speed was related to higher language abilities, but this relationship was not significant when socioeconomic status was controlled for. The magnitude of the association did not differ between the monolingual and bilingual groups across the language measures. Conclusions Slower processing speed is related to lower language abilities in children. Processing speed is minimally influenced by dual language experience, at least within this age range. Supplemental Material https://doi.org/10.23641/asha.12210311.

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 Effects of Lutein and Zeaxanthin Supplementation on Brain Morphology in Older Adults: A Randomized, Controlled Trial

A growing literature emphasizes the importance of lifestyle factors such as nutrition in successful aging. The current study examined if one year of supplementation with lutein (L) and zeaxanthin (Z), two nutrients with known antioxidative properties and cognitive benefits, impacted structural brain outcomes in older adults using a double-blind, randomized, placebo-controlled trial design. Community-dwelling older adults (20 males and 27 females) aged 65–87 years (M = 71.8 years, SD = 6.04 years) were randomized into supplement (N = 33) and placebo groups (N = 14) using simple randomization. The supplement group received 10 mg L + 2 mg Z daily for 12 months while the placebo group received a visually identical, inert placebo. L and Z were measured via retinal concentrations (macular pigment optical density or MPOD). Structural brain outcomes, focusing on global and frontal-temporal lobe regions, were acquired using both T1-weighted and DTI MRI sequences. We hypothesized that the supplement group would increase, maintain, or show attenuated loss in hypothesized regions-of-interest (ROIs) while the placebo group would show age-related declines in brain structural integrity over the course of the trial. While results showed age-related declines for frontal and temporal gray and white matter volumes, as well as fornix white matter microstructure across both groups, only minimal differences were found between the supplement and placebo groups. However, exploratory analyses showed that individuals who responded better to supplementation (i.e., showed greater increases in MPOD) showed less decline in global and prefrontal gray matter volume than supplement “nonresponders.” While results suggest that one year of L and Z supplementation may have limited effects on structural brain outcomes overall, there may be a subsample of individuals for whom supplementation of L and Z provides greater benefits. ClinicalTrials.gov number, NCT02023645.

Effects of macular xanthophyll supplementation on brain-derived neurotrophic factor, pro-inflammatory cytokines, and cognitive performance

PURPOSE

Oxidative and inflammatory processes play a major role in stress-induced neural atrophy. There is a wide body of literature linking oxidative and inflammatory stress with reductions in neurotrophic factors, stress resilience, and cognitive function. Based on their antioxidant and anti-inflammatory capacity, we investigated the effect of the dietary carotenoids lutein and zeaxanthin, along with the zeaxanthin isomer meso-zeaxanthin (collectively the "macular xanthophylls" [MXans]) on systemic brain-derived neurotrophic factor (BDNF) and anti-oxidant capacity (AOC), and the pro-inflammatory cytokines TNF-α, IL-6, and IL-1β. To investigate higher-order effects, we assessed cognitive performance.

METHODS

59 young (18-25 yrs.), healthy subjects participated in a 6-month, double-blind, placebo-controlled trial to evaluate the effects of MXan supplementation on the aforementioned serum parameters and cognitive performance. Subjects were randomly assigned to one of three groups: placebo, 13 mg, or 27 mg/day total MXans; all measures were taken at baseline and 6 months. Blood was obtained via fasting blood draw, and MXan concentration in the retina (termed macular pigment optical density [MPOD]) was measured via customized heterochromatic flicker photometry. Serum BDNF and cytokines were assessed via ELISA. Serum antioxidant capacity (AOC) and serum MXan concentrations were quantified via colorimetric microplate assay, and high-performance liquid chromatography, respectively. Cognitive performance was measured via a computer-based assessment tool (CNS Vital Signs).

RESULTS

BDNF, MPOD, serum MXans, and AOC all increased significantly versus placebo in both treatment groups over the 6-month study period (p < .05 for all). IL-1β decreased significantly versus placebo in both treatment groups (p = .0036 and p = .006, respectively). For cognitive measures, scores for composite memory, verbal memory, sustained attention, psychomotor speed, and processing speed all improved significantly in treatment groups (p < .05 for all) and remained unchanged in the placebo group. Several measures were found to be significantly associated in terms of relational changes over the course of the study. Notably, change in BDNF was related to change in IL-1β (r = -0.47; p < .001) and MPOD (r = 0.44; p = .0086). Additionally, changes in serum MXans were strongly related to AOC (r = 0.79 & 0.61 for lutein and zeaxanthin isomers respectively; p < .001). For cognitive scores, change in BDNF was correlated to change in composite memory (r = 0.32; p = .014) and verbal memory (r = 0.35; p = .007), whereas change in MPOD was correlated with change in both psychomotor speed (r = 0.38; p = .003), and processing speed (r = 0.35; p = .007). Change in serum lutein was found to be significantly correlated to change in verbal memory (r = 0.41; p < .001), composite memory (r = 0.31; p = .009), and sustained attention (r = 0.28; p = .036). Change in serum zeaxanthin isomers was significantly correlated with change in verbal memory (r = 0.33; p = .017). Lastly, change in AOC was significantly associated with verbal memory (r = 0.34; p = .021), composite memory (r = 0.29; p = .03), and sustained attention (r = 0.35; p = .016). No significant relational changes in any cognitive parameter were found for the placebo group.

CONCLUSIONS

Six months of daily supplementation with at least 13 mg of MXans significantly reduces serum IL-1β, significantly increases serum MXans, BDNF, MPOD, and AOC, and improves several parameters of cognitive performance. Findings suggest that increased systemic antioxidant/anti-inflammatory capacity (and not necessarily deposition of the carotenoids in neural tissues), may explain many of the effects determined in this study. The significant relationship between change in BDNF and IL-1β over the course of the study suggests that regular consumption of MXans interrupts the inflammatory cascade that can lead to reduction of BDNF. Changes in MPOD and BDNF appear to account for enhancement in cognitive parameters that involve speed of processing and complex processing, respectively. ISRCTN Clinical Trial Registration: ISRCTN16156382.

Nutritional Intervention to Prevent Alzheimer's Disease: Potential Benefits of Xanthophyll Carotenoids and Omega-3 Fatty Acids Combined

BACKGROUND

A growing body of scientific evidence suggests that enrichment of certain nutritional compounds in the brain may reduce the risk of Alzheimer's disease (AD).

OBJECTIVE

To investigate the impact of supplemental xanthophyll carotenoids plus omega-3 fatty acids on disease progression in patients with AD.

METHODS

Three trial experiments were performed. In Trials 1 and 2 (performed on patients with AD over an 18-month period), 12 patients (AD status at baseline: 4 mild and 8 moderate) were supplemented with a xanthophyll carotenoid only formulation (Formulation 1; lutein:meso-zeaxanthin:zeaxanthin 10:10:2 mg/day) and 13 patients (AD status at baseline: 2 mild, 10 moderate, and 1 severe) were supplemented with a xanthophyll carotenoid and fish oil combination (Formulation 2; lutein:meso-zeaxanthin:zeaxanthin 10:10:2 mg/day plus 1 g/day of fish oil containing 430 mg docohexaenoic acid [DHA] and 90 mg eicopentaenoic acid [EPA]), respectively. In Trial 3, 15 subjects free of AD (the control group) were supplemented for 6 months with Formulation 1. Blood xanthophyll carotenoid response was measured in all trials by HPLC. Omega-3 fatty acids were profiled by direct infusion mass spectrometry.

RESULTS

Xanthophyll carotenoid concentration increases were significantly greater for Formulation 2 compared to Formulation 1 (p < 0.05), and progression of AD was less for this group (p = 0.003), with carers reporting functional benefits in memory, sight, and mood.

CONCLUSION

This preliminary report suggests positive outcomes for patients with AD who consumed a combination of xanthophyll carotenoids plus fish oil, but further study is required to confirm this important observation.

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

Lutein is a non-provitamin A dietary carotenoid found in dark green leafy vegetables, corn, eggs, and avocados. Among the carotenoids, lutein and its isomer, zeaxanthin, are the only 2 that cross the blood-retina barrier to form macular pigment in the retina. Lutein also preferentially accumulates in the human brain across multiple life stages. A variety of scientific evidence supports a role for lutein in visual as well as cognitive function across the lifespan. The purpose of this review is to summarize the latest science on lutein's role in the eye and the brain across different ages.

Carotenoids: How Effective Are They to Prevent Age-Related Diseases?

Despite an increase in life expectancy that indicates positive human development, a new challenge is arising. Aging is positively associated with biological and cognitive degeneration, for instance cognitive decline, psychological impairment, and physical frailty. The elderly population is prone to oxidative stress due to the inefficiency of their endogenous antioxidant systems. As many studies showed an inverse relationship between carotenoids and age-related diseases (ARD) by reducing oxidative stress through interrupting the propagation of free radicals, carotenoid has been foreseen as a potential intervention for age-associated pathologies. Therefore, the role of carotenoids that counteract oxidative stress and promote healthy aging is worthy of further discussion. In this review, we discussed the underlying mechanisms of carotenoids involved in the prevention of ARD. Collectively, understanding the role of carotenoids in ARD would provide insights into a potential intervention that may affect the aging process, and subsequently promote healthy longevity.

Dietary Carotenoids Lutein and Zeaxanthin Change Brain Activation in Older Adult Participants: A Randomized, Double-Masked, Placebo-Controlled Trial

SCOPE

Steady-state visual evoked potentials (SSVEP) can be used to test the topological response of cortical neurons. Studies have shown that a lutein (L) preferentially accumulates within cortical tissue. L, zeaxanthin (Z), and their isomers can be measured directly in retina (macular pigment optical density, MPOD), and retinal L+Z correlate highly with L+Z levels in cortical visual processing areas. The purpose of this study was to determine the relation between MPOD and SSVEP signal power, cross-sectionally and after supplementation with L+Z.

METHODS AND RESULTS

SSVEP to three different driving frequencies of stimulation (5, 10, and 16.6 Hz) were obtained for community-dwelling older adults, at baseline and after 12 months of supplementation with either 12 mg L+Z or placebo. Power was quantified at the driving frequencies. Non-specific activation was quantified within the 10-15 Hz band. MPOD was measured psychophysically. Subjects with low MPOD had reduced power at 16.6 Hz and reduced non-specific activation, compared with subjects with high MPOD. Supplementation significantly improved signal power at 5 and 10 Hz.

CONCLUSION

Past research suggests that L+Z can improve visual memory, visual processing speeds, etc. One possible mechanism for that improvement may be improving signal-to-noise ratio throughout the vision system.

Lutein and zeaxanthin: The possible contribution, mechanisms of action and implications of modern dietary intake for cognitive development in children

Background:Studies suggest that lutein and zeaxanthin may be important for cognitive development in children, but a comprehensive evidence synthesis is lacking. The purpose of this evidence synthesis was to analyse the available data regarding the role of lutein and zeaxanthin for cognition in children and propose a theoretical basis for future studies.Methods:The PubMed, Scopus, the ISRCTN registry and Cochrane Library databases were searched for studies that evaluated the relationship between lutein and zeaxanthin and cognitive function in children. Reference list and ancestry searches were performed on relevant articles. A total of 543 articles were identified, of which six cross-sectional studies were included.Results:The literature search revealed that the evidence concerning the effect of lutein and zeaxanthin on cognition in children is sparse. However, there is some preliminary evidence indicating a positive association between lutein and zeaxanthin and cognition in childhood.Conclusions:The cross-sectional nature of the few studies available and the lack of RCT data indicates a need for further investigation before any firm conclusions can be drawn.

Associations of Lipophilic Micronutrients with Physical and Cognitive Fitness in Persons with Mild Cognitive Impairment

Age-associated cognitive impairment in general and dementia in particular are a global concern. Preventive lifestyle strategies are highly used but there is a lack of information on the reciprocal relationships between nutrition biomarkers and measures of both cognitive and physical performance. To fill this gap of knowledge, the relationship between plasma levels of the robust nutrition- and antioxidant defense-related biomarkers carotenoid and tocopherols and both indicators of cognitive and physical performance was investigated in a group of persons with mild cognitive impairment participating in the NeuroExercise Study at the German Sport University in Cologne, Germany. In 56 participants with full dataset, significant correlations independently of fruit and vegetable intake were found between plasma levels of β-cryptoxanthin and Timed Up&Go test (p < 0.05), γ-tocopherol and number of daily steps (p < 0.01), as well as between four out of six measured carotenoids—lutein; zeaxanthin; β-cryptoxanthin and β-carotene—and the computerized CogState International Shopping List subtest (p < 0.01). In light of the increasing attention towards the nutritional cognitive neuroscience of carotenoids, computerized measures of cognitive performance might be further implemented in future studies investigating the effects of lifestyle interventions against cognitive and physical impairment.

Neural Activation During Visual Attention Differs in Individuals with High versus Low Macular Pigment Density

SCOPE

The neural efficiency hypothesis for lutein (L) and zeaxanthin (Z) suggests that higher levels of L+Z in the central nervous system (CNS) are predictive of stronger stimulus-specific brain responses. Past research suggests that supplementing L+Z can improve neural processing speed and cognitive function across multiple domains, which supports this hypothesis. The purpose of this study is to determine the extent to which CNS L+Z levels predict brain responses using an attentionally taxing task.

METHODS AND RESULTS

Macular pigment optical density (MPOD) is measured at baseline in 85 participants ranging in age from 18-92 years. Brain activation is measured using dense array electroencephalography. Stimuli evoking the signal include a grating array of vertical bars, oscillating at four driving frequencies. Significant stimulus-specific interactions are detected between attend condition, location, and age (p < .002) for unattended image locations, and between age and location (p < .008) for attended locations. Although no differences are found across age by MPOD, this measure is found to be predictive of neural power at parafoveal bar locations (R² .080).

CONCLUSION

CNS L+Z status is related to differences in brain activation in conditions designed to stress visual attention. These differences are strongest for older subjects.

The Role of Nutrition for the Aging Population: Implications for Cognition and Alzheimer's Disease

Improved life expectancy worldwide has resulted in a significant increase in age-related diseases. Dementia is one of the fastest growing age-related diseases, with 75 million adults globally projected to develop the condition by 2030. Alzheimer's disease (AD) is the most common form of dementia and represents the most significant stage of cognitive decline. With no cure identified to date for AD, focus is being placed on preventative strategies to slow progression, minimize the burden of neurological disease, and promote healthy aging. Accumulating evidence suggests that nutrition (e.g., via fruit, vegetables, fish) is important for optimizing cognition and reducing risk of AD. This review examines the role of nutrition on cognition and AD, with specific emphasis on the Mediterranean diet (MeDi) and key nutritional components of the MeDi, namely xanthophyll carotenoids and omega-3 fatty acids. Given their selective presence in the brain and their ability to attenuate proposed mechanisms involved in AD pathogenesis (namely oxidative damage and inflammation), these nutritional compounds offer potential for optimizing cognition and reducing the risk of AD.

The Role of Nutrients in Reducing the Risk for Noncommunicable Diseases during Aging

An increasing aging population worldwide accounts for a growing share of noncommunicable diseases (NCDs) of the overall social and economic burden. Dietary and nutritional approaches are of paramount importance in the management of NCDs. As a result, nutrition programs are increasingly integrated into public health policies. At present, programs aimed at reducing the burden of NCDs have focused mostly on the excess of unhealthy nutrient intakes whereas the importance of optimizing adequate essential and semi-essential nutrient intakes and nutrient-rich diets has received less attention. Surveys indicate that nutrient intakes of the aging population are insufficient to optimally support healthy aging. Vitamin and mineral deficiencies in older adults are related to increased risk of NCDs including fatigue, cardiovascular disease, and cognitive and neuromuscular function impairments. Reviewed literature demonstrates that improving intake for certain nutrients may be important in reducing progress of NCDs such as musculoskeletal disorders, dementia, loss of vision, and cardiometabolic diseases during aging. Current knowledge concerning improving individual nutrient intakes to reduce progression of chronic disease is still emerging with varying effect sizes and levels of evidence. Most pronounced benefits of nutrients were found in participants who had low nutrient intake or status at baseline or who had increased genetic and metabolic needs for that nutrient. Authorities should implement ways to optimize essential nutrient intake as an integral part of their strategies to address NCDs.

The Effect of Lutein on Eye and Extra-Eye Health

Lutein is a carotenoid with reported anti-inflammatory properties. A large body of evidence shows that lutein has several beneficial effects, especially on eye health. In particular, lutein is known to improve or even prevent age-related macular disease which is the leading cause of blindness and vision impairment. Furthermore, many studies have reported that lutein may also have positive effects in different clinical conditions, thus ameliorating cognitive function, decreasing the risk of cancer, and improving measures of cardiovascular health. At present, the available data have been obtained from both observational studies investigating lutein intake with food, and a few intervention trials assessing the efficacy of lutein supplementation. In general, sustained lutein consumption, either through diet or supplementation, may contribute to reducing the burden of several chronic diseases. However, there are also conflicting data concerning lutein efficacy in inducing favorable effects on human health and there are no univocal data concerning the most appropriate dosage for daily lutein supplementation. Therefore, based on the most recent findings, this review will focus on lutein properties, dietary sources, usual intake, efficacy in human health, and toxicity.

Intrinsic and Extrinsic Factors Impacting Absorption, Metabolism, and Health Effects of Dietary Carotenoids

Carotenoids are orange, yellow, and red lipophilic pigments present in many fruit and vegetables, as well as other food groups. Some carotenoids contribute to vitamin A requirements. The consumption and blood concentrations of specific carotenoids have been associated with reduced risks of a number of chronic conditions. However, the interpretation of large, population-based observational and prospective clinical trials is often complicated by the many extrinsic and intrinsic factors that affect the physiologic response to carotenoids. Extrinsic factors affecting carotenoid bioavailability include food-based factors, such as co-consumed lipid, food processing, and molecular structure, as well as environmental factors, such as interactions with prescription drugs, smoking, or alcohol consumption. Intrinsic, physiologic factors associated with blood and tissue carotenoid concentrations include age, body composition, hormonal fluctuations, and variation in genes associated with carotenoid absorption and metabolism. To most effectively investigate carotenoid bioactivity and to utilize blood or tissue carotenoid concentrations as biomarkers of intake, investigators should either experimentally or statistically control for confounding variables affecting the bioavailability, tissue distribution, and metabolism of carotene and xanthophyll species. Although much remains to be investigated, recent advances have highlighted that lipid co-consumption, baseline vitamin A status, smoking, body mass and body fat distribution, and genetics are relevant covariates for interpreting blood serum or plasma carotenoid responses. These and other intrinsic and extrinsic factors are discussed, highlighting remaining gaps in knowledge and opportunities for future research. To provide context, we review the state of knowledge with regard to the prominent health effects of carotenoids.

Carotenoids in human nutrition and health

Carotenoids are naturally occurring pigments found in most fruits and vegetables, plants, algae, and photosynthetic bacteria. Humans cannot synthesize carotenoids and must ingest them in food or via supplementation. Carotenoids have a range of functions in human health. They primarily exert antioxidant effects, but individual carotenoids may also act through other mechanisms; for example, β-carotene has a pro-vitamin A function, while lutein/zeaxanthin constitute macular pigment in the eye. The benefit of lutein in reducing progression of age-related macular eye disease and cataracts is strengthening; an intake recommendation would help to generate awareness in the general population to have an adequate intake of lutein rich foods. There is evidence that carotenoids, in addition to beneficial effects on eye health, also produce improvements in cognitive function and cardiovascular health, and may help to prevent some types of cancer. Despite the evidence for the health benefits of carotenoids, large population-based supplementation studies have produced mixed results for some of the carotenoids. To establish and confirm the health benefits of the different carotenoids more research, including clinical studies, is needed.

Rod-Mediated Dark Adaptation and Macular Pigment Optical Density in Older Adults with Normal Maculas

PURPOSE

To examine the association between macular pigment optical density (MPOD) and rod-mediated dark adaptation (RMDA) in persons ≥60 years old with normal maculas as determined by an accepted color fundus photography grading system.

METHODS

This cross-sectional analysis used baseline data from eyes in the Alabama Study on Early Age-Related Macular Degeneration. Eyes at step 1 in the AREDS 9-step grading system were considered normal. Eyes were additionally assessed by spectral domain optical coherence tomography (SD-OCT). Foveal MPOD was estimated via heterochromatic flicker photometry, and RMDA was assessed with a computerized dark adaptometer. The association between RMDA and MPOD was examined via Spearman correlation coefficients adjusted for age.

RESULTS

In 306 eyes from 306 persons (mean age 68.2 years) in normal macular health, MPOD was not associated with RMDA (age-adjusted rank correlation = 0.043, p = 0.45). After 81 eyes with incidental macular findings by SD-OCT evaluation were excluded, the association between MPOD and RMDA remained null (N = 225, age-adjusted r = 0.015, p = 0.82).

CONCLUSION

In a large sample of normal aged eyes, RMDA, a visual function that is rate limited by retinoid availability to photoreceptors across the complex of retinal pigment epithelium, Bruch's membrane, and choriocapillaris, is not related to MPOD in the neurosensory retina.

Lutein and Zeaxanthin Are Positively Associated with Visual-Spatial Functioning in Older Adults: An fMRI Study

Lutein (L) and zeaxanthin (Z) are two xanthophyll carotenoids that have antioxidant and anti-inflammatory properties. Previous work has demonstrated their importance for eye health and preventing diseases such as age-related macular degeneration. An emerging literature base has also demonstrated the importance of L and Z in cognition, neural structure, and neural efficiency. The present study aimed to better understand the mechanisms by which L and Z relate to cognition, in particular, visual–spatial processing and decision-making in older adults. We hypothesized that markers of higher levels of L and Z would be associated with better neural efficiency during a visual–spatial processing task. L and Z were assessed via standard measurement of blood serum and retinal concentrations. Visual–spatial processing and decision-making were assessed via a judgment of line orientation task (JLO) completed during a functional magnetic resonance imaging (fMRI) scan. The results demonstrated that individuals with higher concentrations of L and Z showed a decreased blood-oxygen-level dependent (BOLD) signal during task performance (i.e., “neural efficiency”) in key areas associated with visual–spatial perception, processing, decision-making, and motor coordination, including the lateral occipital cortex, occipital pole, superior and middle temporal gyri, superior parietal lobule, superior and middle frontal gyri, and pre- and post-central gyri. To our knowledge, this is the first investigation of the relationship of L and Z to visual–spatial processing at a neural level using in vivo methodology. Our findings suggest that L and Z may impact brain health and cognition in older adults by enhancing neurobiological efficiency in a variety of regions that support visual perception and decision-making.

The Macular Carotenoids are Associated with Cognitive Function in Preadolescent Children

The macular carotenoids lutein (L) and zeaxanthin (Z) are obtained via diet and accumulate in the central retina where they are referred to as macular pigment. The density of this biomarker (macular pigment optical density; MPOD) has been positively correlated with cognitive functioning via measures of global cognition, processing speed, and visual-spatial abilities, among others. Although improvements in cognitive function have been found in adults, much less is known about how L and Z intake may support or improve cognitive functioning during periods of rapid developmental change, such as childhood and pre-adolescence. This study examined the relationship between MPOD and cognitive functioning in 51 7–13-year-old children (51% female). MPOD was measured using heterochromatic flicker photometry (HFP) optimized for this age group. Cognitive function was assessed using the Woodcock-Johnson III (composite standard scores were obtained for Brief Intellectual Ability, Verbal Ability, Cognitive Efficiency, Processing Speed, and Executive Processes). In this sample, MPOD was significantly related to Executive Processes, r(47) = 0.288, p < 0.05, and Brief Intellectual Ability, r(47) = 0.268, p < 0.05. The relationship to Cognitive Efficiency was positive and trending but not significant, r(49) = 0.206, p = 0.074. In general, these data are consistent with those of adults showing a link between higher carotenoid status and improved cognitive functioning.

Lutein and Zeaxanthin Influence Brain Function in Older Adults: A Randomized Controlled Trial

OBJECTIVES

The present study constitutes the first randomized controlled trial to investigate the relation of lutein (L) and zeaxanthin (Z) to brain function using functional magnetic resonance imaging (fMRI). It was hypothesized that L and Z supplementation in older adults would enhance neural efficiency (i.e., reduce activation) and cognitive performance on a verbal learning task relative to placebo.

METHODS

A total of 44 community-dwelling older adults (mean age=72 years) were randomly assigned to receive either placebo or L+Z supplementation (12 mg/daily) for 1 year. Neurocognitive performance was assessed at baseline and post-intervention on an fMRI-adapted task involving learning and recalling word pairs. Imaging contrasts of blood-oxygen-level-dependent (BOLD) signal were created by subtracting active control trials from learning and recall trials. A flexible factorial model was employed to investigate the expected group (placebo vs. supplement) by time (baseline vs. post-intervention) interaction in pre-specified regions-of-interest.

RESULTS

L and Z appeared to buffer cognitive decline on the verbal learning task (Cohen's d=.84). Significant interactions during learning were observed in left dorsolateral prefrontal cortex and anterior cingulate cortex (p < .05, family-wise-error corrected). However, these effects were in the direction of increased rather than decreased BOLD signal. Although the omnibus interaction was not significant during recall, within-group contrasts revealed significant increases in left prefrontal activation in the supplement group only.

CONCLUSIONS

L and Z supplementation appears to benefit neurocognitive function by enhancing cerebral perfusion, even if consumed for a discrete period of time in late life. (JINS, 2018, 24, 77-90).