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