Women's Health Initiative diet intervention did not increase macular pigment optical density in an ancillary study of a subsample of the Women's Health Initiative

A review of the putative causal mechanisms associated with lower macular pigment in diabetes mellitus

Macular pigment (MP) confers potent antioxidant and anti-inflammatory effects at the macula, and may therefore protect retinal tissue from the oxidative stress and inflammation associated with ocular disease and ageing. There is a body of evidence implicating oxidative damage and inflammation as underlying pathological processes in diabetic retinopathy. MP has therefore become a focus of research in diabetes, with recent evidence suggesting that individuals with diabetes, particularly type 2 diabetes, have lower MP relative to healthy controls. The present review explores the currently available evidence to illuminate the metabolic perturbations that may possibly be involved in MP's depletion. Metabolic co-morbidities commonly associated with type 2 diabetes, such as overweight/obesity, dyslipidaemia, hyperglycaemia and insulin resistance, may have related and independent relationships with MP. Increased adiposity and dyslipidaemia may adversely affect MP by compromising the availability, transport and assimilation of these dietary carotenoids in the retina. Furthermore, carotenoid intake may be compromised by the dietary deficiencies characteristic of type 2 diabetes, thereby further compromising redox homeostasis. Candidate causal mechanisms to explain the lower MP levels reported in diabetes include increased oxidative stress, inflammation, hyperglycaemia, insulin resistance, overweight/obesity and dyslipidaemia; factors that may negatively affect redox status, and the availability, transport and stabilisation of carotenoids in the retina. Further study in diabetic populations is warranted to fully elucidate these relationships.

Effect of Long-Term Xanthophyll and Anthocyanin Supplementation on Lutein and Zeaxanthin Serum Concentrations and Macular Pigment Optical Density in Postmenopausal Women

Xanthophylls (lutein, L; zeaxanthin, Z) and anthocyanins are often included in food supplements to improve ocular health. There are no dietary reference intakes for them. The aim was to assess the effects of L, Z and anthocyanin supplementation on short and long-term lutein status markers (serum concentration and macular pigment optical density (MPOD)). Seventy-two postmenopausal women were randomized into a parallel study of 8 months: Group A-anthocyanines (60 mg/day); Group X-xanthophylls (6 mg L + 2 mg Z/day); Group X+A-anthocyanines (60 mg/day) + xanthophylls (6 mg L + 2 mg Z/day). At the beginning of the study, 4 and 8 month serum L and Z concentrations were determined (HPLC), as well as L, Z and anthocyanine dietary intake and MPOD (heterochromic flicker photometry). Baseline concentrations of L (0.35 ± 0.19 μmol/L), Z (0.11 ± 0.05 μmol/L), L+Z/cholesterol/triglycerides (0.07 ± 0.04 μmol/mmol) increased in Group X (2.8- and 1.6-fold in L and Z concentrations) and in group XA (2- and 1.4-fold in L and Z concentrations). MPOD (baseline: 0.32 ± 0.13 du) was not modified in any of the groups at the end of the study. There were no differences in the dietary intake of L+Z and anthocyanin at any point in time in any group. Supplementation of L and Z at a dietary level provoked an increase in their serum concentration that was not modified by simultaneous supplementation with anthocyanins.

Effects of Lutein/Zeaxanthin Supplementation on the Cognitive Function of Community Dwelling Older Adults: A Randomized, Double-Masked, Placebo-Controlled Trial

Background: High levels of xanthophyll carotenoids lutein (L) and zeaxanthin (Z) in the central nervous system have been previously correlated with improved cognitive function in community-dwelling older adults. In this study, we tested the effects of supplementing L and Z on older men and women with a range of baseline cognitive abilities.

Objective: The purpose of this study was to determine whether or not supplementation with L+Z could improve cognitive function in community-dwelling, older adults.

Design: Double-masked, randomized, placebo-controlled trial. A total of 62 older adults were randomized into groups receiving either 12 mg L+Z or a visually identical placebo. Data from 51 participants (M = 73.7 years) were available for analysis. Retinal L+Z levels (macular pigment optical density, MPOD) were measured psychophysically using heterochromatic flicker photometry as a biomarker of cortical L+Z levels. Cognitive function was measured using the CNS Vital Signs computerized test platform.

Results: Participants receiving the active L+Z supplement had statistically significant increases in MPOD (p < 0.03) and improvements in complex attention (p < 0.02) and cognitive flexibility domains (p < 0.04), relative to participants taking the placebo. A trend was also seen for the executive function domain (p = 0.073). In male participants only, supplementation yielded improved composite memory (p = 0.04).

Conclusions: Supplementation with L+Z improved cognitive function in community-dwelling, older men and women.

Lutein and zeaxanthin supplied by red/orange foods and fruits are more closely associated with macular pigment optical density than those from green vegetables in Spanish subjects

Lutein and zeaxanthin (L+Z) accumulate in the retina. Although vegetables are major contributors to their intake, a stronger association between fruits and macular pigment optical density (MPOD) has been reported. We hypothesized that L+Z intake from fruits would have a stronger association with L+Z status markers (MPOD, serum concentrations) than intake from vegetables or eggs, and that those associations would also differ according to plant foods color. One hundred eight subjects (57 men; age groups, 20-35 and 45-65 years) were enrolled in a cross-sectional study. L+Z intake from fruits, vegetables, and eggs was determined using three 24-hour diet recalls and a country-specific carotenoid database. Vegetables were the major contributors (75%) to L+Z intake, followed by eggs (10%) and fruits (4%). Vegetables supplied 86% and 84% of the LandZ intake, respectively, and fruits supplied 3% and 16%. Green foods supplied 78% and 52% of LandZ, respectively, followed by red/orange (9% and 38%) and white/yellow (14% and 9%). Factorial analysis showed associations in older subjects. The explained variance of the first 2 principal components was 54% considering L+Z intake from fruits, vegetables, and eggs, and 55% considering L+Z intake from plant foods grouped by color. Macular pigment optical density is related to L+Z intake from fruits (0.264, P=.003) and is independent of that from vegetables and eggs. It is related to L+Z intake from red/orange foods (0.320, P=.000) and the serum concentrations to that from green foods (0.222, P=.11). Although vegetables and green foods of plant origin are the major contributors to L+Z intake, red/orange foods and fruits have the strongest relationship to MPOD in study participants (45-65 years of age).

Measurement of macular pigment optical density among healthy Chinese people and patients with early-stage age-related macular degeneration

AIM

To measure the macular pigment optical density (MPOD) in healthy Chinese people and patients with early age-related macular degeneration (AMD).

METHODS

Cross-sectional population based study. Demographic and lifestyle characteristics were ascertained by questionnaire. A food frequency questionnaire was completed for all participants. Participants underwent general physical and ophthalmic examinations and MPOD was measured by heterochromatic flicker photometry. Foveal architecture was measured by optical coherence tomography.

RESULTS

MPOD of 225 participants (122 healthy and 103 early AMD) was 0.48±0.18. Patients with early AMD (0.52±0.19) tended to have higher MPOD levels than healthy people (0.47±0.17), but the difference was not statistically significant (P=0.06). Participants with carrot or corn oil intake every week tended to have higher levels of MPOD (P=0.002 and 0.008 respectively) while those with corn intake had relatively lower level of MPOD (P=0.01). MPOD increased with the center foveal thickness (P=0.01).

CONCLUSION

Our findings show that there is no statistically significant association between MPOD and early AMD in the studied population. MPOD is related to center foveal thickness and diets would influence MPOD levels.

Dietary modification and supplementation for the treatment of age-related macular degeneration

Age-related macular degeneration (AMD) causes a significant proportion of visual loss in the developed world. Currently, little is known about its pathogenesis, and treatment options are limited. Dietary intake is one of the few modifiable risk factors for this condition. The best-validated therapies remain oral antioxidant supplements based on those investigated in the Age-Related Eye Disease Study (AREDS) and the recently completed Age-Related Eye Disease Study 2 (AREDS2). In this review, current dietary guidelines related to AMD, along with the underlying evidence to support them, are presented in conjunction with current treatment recommendations. Both AREDS and AREDS2 are discussed, as are avenues for further research, including supplementation with vitamin D and saffron. Despite the considerable disease burden of atrophic AMD, few effective therapies are available to treat it, and further research is required.

An Evidence-Based Systematic Review of Lutein by the Natural Standard Research Collaboration

An evidence-based systematic review of lutein by the Natural Standard Research Collaboration consolidates the safety and efficacy data available in the scientific literature using a validated, reproducible grading rationale. This article includes written and statistical analysis of clinical trials, plus a compilation of expert opinion, folkloric precedent, history, pharmacology, kinetics/dynamics, interactions, adverse effects, toxicology, and dosing.

Healthy lifestyles related to subsequent prevalence of age-related macular degeneration

OBJECTIVE

To investigate the relationships between lifestyle behaviors of diet, smoking, and physical activity and the subsequent prevalence of age-related macular degeneration (AMD).

METHODS

The population included 1313 participants (aged 55-74 years) in the Carotenoids in Age-Related Eye Disease Study, an ancillary study of the Women's Health Initiative Observational Study. Scores on a modified 2005 Healthy Eating Index were assigned using responses to a food frequency questionnaire administered at baseline of the Women's Health Initiative Observational Study (1994-1998). Physical activity and lifetime smoking history were queried. An average of 6 years later, stereoscopic fundus photographs were taken to assess the presence and severity of AMD; it was present in 202 women, 94% of whom had early AMD, the primary outcome.

RESULTS

In multivariate models, women whose diets scored in the highest quintile compared with the lowest quintile on the modified 2005 Healthy Eating Index had 46% lower odds for early AMD. Women in the highest quintile compared with those in the lowest quintile for physical activity (in metabolic energy task hours per week) had 54% lower odds for early AMD. Although smoking was not independently associated with AMD on its own, having a combination of 3 healthy behaviors (healthy diet, physical activity, and not smoking) was associated with 71% lower odds for AMD compared with having high-risk scores (P < .001).

CONCLUSION

Modifying lifestyles might reduce risk for early AMD as much as 3-fold, lowering the risk for advanced AMD in a person's lifetime and the social and economic costs of AMD to society.