A review of the evidence germane to the putative protective role of the macular carotenoids for age‐related macular degeneration

Abstract

There is a consensus that age‐related macular degeneration (AMD) is the result of (photo)‐oxidative‐induced retinal injury and its inflammatory sequelae, the latter being influenced by genetic background. The dietary carotenoids, lutein (L), zeaxanthin (Z), and meso‐zeaxanthin (meso‐Z), accumulate at the macula, where they are collectively known as macular pigment (MP). The anatomic (central retinal), biochemical (anti‐oxidant) and optical (short‐wavelength‐filtering) properties of this pigment have generated interest in the biologically plausible rationale that MP may confer protection against AMD. Level 1 evidence has shown that dietary supplementation with broad‐spectrum anti‐oxidants results in risk reduction for AMD progression. Studies have demonstrated that MP rises in response to supplementation with the macular carotenoids, although level 1 evidence that such supplementation results in risk reduction of AMD and/or its progression is still lacking. Although appropriately weighted attention should be accorded to higher levels of evidence, the totality of available data should be appraised in an attempt to inform professional practice. In this context, the literature demonstrates that supplementation with the macular carotenoids is probably the best means of fortifying the anti‐oxidant defences of the macula, thus putatively reducing the risk of AMD and/or its progression.

The Heritability of Macular Response to Supplemental Lutein and Zeaxanthin: A Classic Twin Study

“…The extensive literature in this regard recently has been reviewed extensively, and can be summarized as follows: most studies demonstrate a relative lack of MP in association with risk-factors for AMD, and the few reported clinical trials indicated a benefit is association with supplemental L and Z. 34 Level 1 evidence that supplementation with antioxidants is beneficial in AMD does exist in the form of the Age Related Eye Disease Study (AREDS), 35 but this evidence does not extend to the macular carotenoids, which is the subject of AREDS II. 36 In any case, any beneficial effect of supplementation with the macular carotenoids rests on the premise that such supplementation does, indeed, result in augmentation of MP.…”

Concordance of Macular Pigment Measurement Using Customized Heterochromatic Flicker Photometry and Fundus Autofluorescence in Age-Related Macular Degeneration

“…10 Macular pigment (and its constituent carotenoids) may have an important role in age-related macular degeneration (AMD) by reducing oxidative stress via its antioxidant properties as well as limiting the effect of inflammatory mediators in the pathogenesis of this condition. 11 Some studies also have reported that MP may be lower compared to controls among persons with glaucoma, 12 Alzheimer's disease (AD), 13 and diabetes, 14,15 suggesting that MP could be a useful biomarker for these conditions, providing a biologically plausible rationale to investigate whether MP has a role in these pathologies.…”

Education Is Positively Associated with Macular Pigment: The Irish Longitudinal Study on Ageing (TILDA)

“…3 The role of MP relates to its blue light filtering properties and its antioxidant potential. 4,5 There is a growing consensus that MP is important for optimal visual performance, 6,7 and it is biologically plausible that this pigment protects against AMD, the leading cause of blind registration in the developed world. 4,5 Beyond diet, the determinants of MP may include genetic background 8 and known and putative risk factors for AMD (e.g., age, tobacco use, obesity, cumulative exposure to light, ethnicity).…”

“…4,5 There is a growing consensus that MP is important for optimal visual performance, 6,7 and it is biologically plausible that this pigment protects against AMD, the leading cause of blind registration in the developed world. 4,5 Beyond diet, the determinants of MP may include genetic background 8 and known and putative risk factors for AMD (e.g., age, tobacco use, obesity, cumulative exposure to light, ethnicity). 9 However, studies conducted to date have been based on convenience or volunteer samples recruited from local populations, which are often limited by small sample size and selection bias.…”