Slow the progression of age - related Macular degeneration (AMD) through diet
A randomized clinical trial observed that two caroitenoids called lutein and zeaxanthin can slow the progression of age - related Macular degeneration (AMD). It was observed that lutein and zeaxanthin are retinoprotective.
In this clinical trial, 56 participants consumed 60ml of Lutein complex (LC) derived from marigold (lutein) and wolfberry (zeaxanthin) for 5 months.
The results of supplementing diet with Lutein Complex were promising as it was observed that inflammatory markers, best-corrected visual acuity (BCVA), and intraocular pressure (IOP) were lowered in subjects when treated with LC for 5 months. As a result, long-term consumption of LC may suppress the oxidative stress by enhancing the antioxidant status and thereby preclude the incidence of AMD.
Lutein effects on AMD were observed in mice that were exposed to light (2000 lux, 3 h). The retinal pigment epithelium (RPE) showed disruption at 12h. The disruption remained 48 hours after light exposure. However, this was ameliorated in the mice treated with intraperitoneal lutein at 12 h, suggesting that lutein promoted tight junction repair.
The role of zeaxanthin in slowing the progression of age - related Macular degeneration (AMD) was established by a study that found people with lower plasma concentrations of zeaxathin had higher chances of developing AMD.
Where does Lutein and zeaxanthin accumulate in the eye?
Lutein belongs to the xanthophyll family of carotenoids, which are synthesized within dark green leafy plants.
There is evidence that carotenoids help to retard some of the destructive processes in the retina and the retinal pigment epithelium that lead to age-related degeneration of the macula.
A study that measured The carotenoid pigments in the whole human retina, and in the macular region found that
lutein and zeaxanthin, are deposited at an up to 5 fold higher content in the macular region of the retina, as compared to the peripheral retina. Zeaxanthin is preferentially accumulated in the foveal region, whereas lutein is abundant in the parafoveal region.
Lutein and zeaxathin slows the progression of age related macular degeneration in two ways:
Current studies suggest that lutein is predominantly restricted to its function of quenching harmful triplet chlorophyll ( light- absorbing pigment). Triplet excited chlorophyll is known to act as the photosensitizer in photosynthesis, passing excitation energy to oxygen, thus forming singlet oxygen, results in lipid peroxidation, a chain reaction that can result in tissue damage.
zeaxanthin on the other hand is the major player in the deactivation of excited singlet chlorophyll and thus in NPQ (non-photochemical quenching, which is a process that starts in Response to Excess Light Energy.
The accumulation of oxygen radicals and lipid peroxidation, resulting from increased retinal oxygen utilization, has been postulated as a mechanism for photoreceptor death. But, zeaxanthin serves an important function as an antioxidant because it protects ocular tissues against singlet oxygen and lipid peroxide damage.
What are the foods containing Lutein and zeaxanthin?
A study on eye nutrition suggested that a dietary supplement of zeaxanthin (8 mg daily) and lutein (9 mg daily)specifically enhanced high-contrast visual acuity and shape discrimination.
It was established that Lutein is mostly found in most fruits and vegetables, while zeaxanthin is present only in minute quantities in most fruits, green leafs and vegetable like: Spinach, kale, orange, corn, nectarines, melon, papaya, squash, Orange pepper and the dried fruit of Lycium barbarum (fructus lycii) prescribed by the Chinese herbalists. The highest mole percentage of both lutein and zeaxanthin can be found in egg yolk and maize.
Age - related macular degeneration is a leading cause of vision loss in the USA, according to the National eye institute. So given that lutein and zeaxanthin are the only carotenoids found in the macula and comprise the macular pigment, this suggests that the observed protective effects of high fruit and vegetable intake may be a promising natural way to slow the progression of AMD.