Elsevier

Nutrition

Volume 29, Issues 11–12, November–December 2013, Pages 1412-1417
Nutrition

Pilot study
Age-related macular degeneration: Effects of a short-term intervention with an oleaginous kale extract—a pilot study

https://doi.org/10.1016/j.nut.2013.05.012Get rights and content

Abstract

Objective

Age-related macular degeneration (AMD) is a multifactorial degenerative disease of the retina, which accounts for slowly progressive visual impairment in the elderly. An increased dietary intake of xanthophylls is suggested to be inversely related to the risk of macular disease.

Methods

The present study was designed as a randomized, double-blind, placebo-controlled, parallel trial examining the influence of a short-term intervention with an oleaginous extract of Brassica oleracea var. sabellica L. (kale) on plasma xanthophyll concentrations and the optical density of the macular pigment xanthophylls (MPOD). Twenty patients with non-exudative AMD were recruited for a 10-wk study period (2-wk run-in, 4-wk intervention, 4-wk washout). All participants received 50 mL of a beverage containing either an oleaginous extract of kale (kale) or refined rapeseed oil (placebo). The verum product provides 10 mg lutein and 3 mg zeaxanthin per day.

Results

The concentrations of the xanthophylls in plasma and the MPOD increased significantly in the kale group after 4 wk of intervention. The successive washout period resulted in a significant decline of the values in plasma and macula. The values at the end of the study were still significantly higher than the initial values. Nevertheless, the improvements did not persist over 4 wk of washout.

Conclusion

The distribution of the xanthophylls in the macula seems to be more dynamic than originally assumed.

Introduction

Age-related macular degeneration (AMD) is the primary cause of blindness in industrialized countries and takes third place after cataracts and glaucoma globally. Two forms of advanced AMD exist. The geographic atrophy is the “dry” form and concerns the majority of patients. It is characterized by the accumulation of lipofuscin in the retinal pigment epithelium and the formation of drusen at Bruch's membrane. The apoptotic death of photoreceptors is a result of multifactorial degenerative processes and accounts for a slowly progressive visual impairment. The exudative form, also termed as the “wet” form arises from choroidal neovascularization and leads to a severe and rapid decline in vision. The wet form is usually preceded by the dry form of the disease. There is no cure for the latter. However, data suggest that there are mainly three strategies of prevention: abstinence from cigarette smoking [1], [2], [3], protection of the eyes from extended sunlight exposure [4], [5], [6], and a balanced diet rich in dark green, leafy vegetables [7], [8], [9].

The concept of the present study was to examine whether a dietary intervention is potent to alter the concentrations of xanthophylls in plasma and macula of AMD patients. Supplements mainly provide synthetic or purified xanthophylls. Hence, the special aspect was to study the effects of a nonpurified, non-saponified oleaginous extract of kale. Therefore, a pilot study was designed to examine the following issues.

  • 1.

    Does a 4-wk intervention with an oleaginous extract of kale influence plasma lutein and zeaxanthin concentrations in patients with non-exudative AMD?

  • 2.

    Is the optical density of the macular pigment xanthophylls (MPOD) affected by the short-term intervention?

  • 3.

    Does a 4-wk washout period effect the concentrations of xanthophylls in plasma and the MPOD?

Section snippets

Methods

The study is registered at ClinicalTrials.gov (NCT01316198). This study was conducted according to the guidelines laid down in the Declaration of Helsinki and all procedures involving human patients were approved by the ethics committee of the Friedrich Schiller University Jena (ethical vote no. 2449-12/08).

Results

All recruited participants (13 men, 7 women) finished the study successfully. Their main characteristics are summarized in Table 2. Furthermore, the table shows that the baseline data did not differ between the two treatment groups.

Discussion

This pilot study examined the influence of a short-term intervention with an oleaginous extract of kale on plasma lutein and zeaxanthin concentrations and the MPOD in patients with AMD.

In general, the main outcomes of the present study were the following. First, the treatment with the oleaginous extract of kale elevated the xanthophyll concentrations in plasma significantly. Likewise, the distribution parameters of the macular pigment xanthophylls increased significantly (except of mean OD).

Conclusion

An oleaginous extract of kale is able to elevate the xanthophyll concentrations in blood and macula of AMD patients. Both effects did not persist over a 4-wk washout period. Hence, a continuous and adequate uptake of xanthophylls is necessary to counteract the declining values. Further studies should elucidate whether a tailored nutritional concept can be as effective as supplements in maintaining the levels.

Acknowledgments

This work was supported by Institut Danone Ernährung für Gesundheit e.V. (Germany). Special thanks go to BioActive Food GmbH (Germany) for the development and the production of the study beverages. The skillful technical support of Lisa Winter is gratefully acknowledged. Last but not least, a great thanks to all volunteers for participation.

References (34)

  • A.J. Wenzel et al.

    12-wk egg intervention increases serum zeaxanthin and macular pigment optical density in women

    J Nutr

    (2006)
  • J.T. Landrum et al.

    A one year study of the macular pigment: the effect of 140 days of a lutein supplement

    Exp Eye Res

    (1997)
  • Risk factors associated with age-related macular degeneration. A case–control study in the age-related eye disease study: Age-Related Eye Disease Study Report Number 3

    Ophthalmology

    (2000)
  • J.E. Roberts

    Ultraviolet radiation as a risk factor for cataract and macular degeneration

    Eye contact lens

    (2011)
  • S.C. Tomany et al.

    Sunlight and the 10-year incidence of age-related maculopathy: the Beaver Dam Eye Study

    Arch Ophthalmol

    (2004)
  • H.R. Taylor et al.

    The long-term effects of visible light on the eye

    Arch Ophthalmol

    (1992)
  • J.M. Seddon et al.

    Dietary carotenoids, vitamins A, C, and E, and advanced age-related macular degeneration

    JAMA

    (1994)
  • Cited by (0)

    CA contributed to study procedure, analyzed carotenoid levels in plasma, did the statistical analysis of data, and wrote the manuscript. SJ measured the macular pigment parameters and took part in data analysis. JD contributed to the study conception and data interpretation. VB was involved in experimental design, data interpretation, and writing of the manuscript. There are no financial or other contractual agreements that may cause conflicts of interests.

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