The role of the carotenoids, lutein and zeaxanthin, in protecting against age-related macular degeneration: A review based on controversial evidence
Nutrition Journal
The role of the carotenoids, lutein and zeaxanthin, in protecting against age-related macular degeneration: A review based on controversial evidence
Maneli Mozaffarieh 0
Stefan Sacu 0
Andreas Wedrich andreas.wedrich@akh- 0
0 Address: Department of Ophthalmology, University of Vienna , Austria
Purpose: A review of the role of the carotenoids, lutein and zeaxanthin, and their function in altering the pathogenesis of age-related macular degeneration (AMD). Methods: Medline and Embase search. Results: Recent evidence introduces the possibility that lutein and zeaxanthin, carotenoids found in a variety of fruits and vegetables may protect against the common eye disease of macular degeneration. This potential and the lack to slow the progression of macular degeneration, has fueled high public interest in the health benefits of these carotenoids and prompted their inclusion in various supplements. The body of evidence supporting a role in this disease ranges from basic studies in experimental animals to various other clinical and epidemiological studies. Whilst some epidemiological studies suggest a beneficial role for carotenoids in the prevention of AMD, others are found to be unrelated to it. Results of some clinical studies indicate that the risk for AMD is reduced when levels of the carotenoids are elevated in the serum or diet, but this correlation is not observed in other studies. Published data concerning the toxicity of the carotenoids or the optimum dosage of these supplements is lacking. Conclusion: An intake of dietary supplied nutrients rich in the carotenoids, lutein and zeaxanthin, appears to be beneficial in protecting retinal tissues, but this is not proven. Until scientifically sound knowledge is available we recommend for patients judged to be at risk for AMD to: alter their diet to more dark green leafy vegetables, wear UV protective lenses and a hat when outdoors. Future investigations on the role of nutrition, light exposure, genetics, and combinations of photodynamic therapy with intravitreal steroid (triamcinolone-acetonide) injections hold potential for future treatment possibilities.
age-related macular degeneration (AMD)carotenoidsvitamin supplements
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ina are lutein and zeaxanthin [1,2]. Similar to -carotene,
these pigments are found in various coloured fruits and
green leafy vegetables. Of the 40 to 50 carotenoids
typically consumed in the human diet [3,4], lutein and
zeaxanthin, are deposited at an up to 5 fold higher content in
the macular region of the retina [1] as compared to the
peripheral retina. Zeaxanthin is preferentially
accumulated in the foveal region [2,5], whereas lutein is abundant
in the perifoveal region. These pigments are collectively
referred to as the macular pigment (MP). Although the
role of the macular pigment remains uncertain, several
functions have been hypothesised and these include
limitation of the damaging photo-oxidative effects of blue
light through its absorption [6-8], reduction of the effects
of light scatter and chromatic aberration on visual
performance, [9,10], and protection against the adverse
effects of photochemical reactions because of the
antioxidant properties of the carotenoids [5,11,12].
Age related macular degeneration (AMD) is the leading
cause of irreversible vision loss in the elderly population
in the USA and the Western world. It is estimated that
1.6% of the population in the 50-to 65-year-old age group
is affected, rising to 30% in the over-75-year-old age
group. As the proportion of the elderly in our population
increases, the public health impact of AMD will become
even more severe Although the aetiopathogenesis of AMD
remains a matter of debate, there is a growing body of
evidence to indicate that oxidative damage plays a role
[13,14]. Consequently, the possibility that the absorption
characteristics and antioxidant properties of macular
pigment confer protection against age-related macular
degeneration has been postulated [12,15] and it has further
been hypothesised that dietary supplementation with
lutein and / or zeaxanthin might protect the retina and /
or delay the progression of age-related macular
degeneration [12,16-18]. Supplementation with foods [19-21] or
supplements rich in lutein or zeaxanthin has been
reported to increase macular pigment density in most, but
not all, human subjects [19,21,22]. Yet despite the
possible importance of these carotenoids in modulating the
course of age-related macular degeneration, critical
evidence of beneficial effect has not been found, and the role
that these carotenoid supplements play in patients with
age-related macular degeneration, or those at risk of
developing the disease, remains unproved. In this article we
review the current literature present on carotenoids and
focus particularly on the controversial evidence that
retinal carotenoids are protective against age-related macular
degeneration.
Results
Age related macular degeneration
Definition an (...truncated)