Related Information: View / Listen to an Interview with Paul Bernstein, MD, PhD on the Role of Lutein & zeaxanthin in Macular Health

The results from a new NEI-sponsored study suggest that low ocular levels of antioxidants lutein and zeaxanthin - carotenoids found in dark green, leafy vegetables such as spinach and kale - could contribute to age-related macular degeneration (AMD). The research team also reports that AMD patients who had begun taking high-dose lutein supplements after initially diagnosed with AMD were able return those levels back to normal (1).

The investigators' primary objective was to quantify and compare macular pigment levels in AMD and normal subjects. Macular carotenoid levels were measured in 93 eyes from 63 patients with AMD and in 220 normal eyes from 138 volunteers using resonance Raman spectroscopy - a method which measures the signal intensity generated by the carbon-carbon double bond vibrations of lutein and zeaxanthin. Because this method provides a non-invasive, objective and sensitive means to determine carotenoid levels and optical density in the eyes of living people, it is particularly useful in large-scale clinical studies.

Macular carotenoid levels declined with age, reaching a stable low level after age 60, when AMD incidence begins to rise dramatically (Fig 1). They also found that macular pigment levels in the eyes of AMD patients not consuming high-dose lutein supplements were 32 percent lower than elderly normal eyes (p = 0.001) (Fig 2). Patients who began taking high dose lutein supplements (ranging from 4 - 20 mg) after their initial AMD diagnosis had significantly higher macular pigment levels compared to those who did not (p = 0.038). In fact, macular content of the AMD patients using high-dose supplements was also similar to that of normals.

Figure 1.

"These results taken together lead us to believe that low macular levels of lutein and zeaxanthin represent a pathogenic risk factor for the development of AMD," (2,3) said lead investigator Paul Bernstein. "As a safeguard, patients at risk for visual loss from AMD should consider supplementing their diets with at least 4 mg of lutein each day along with other antioxidant nutrients."

Figure 2.

Resonance Raman Measurement of Macular Carotenoids in Elderly Normal and AMD Patients. Type Patient No. Eyes (No. Patients) Resonance Signal Intensity at 1525 cm (Mean counts ± SD)* Normal 73 (52) 219 ± 134 AMD    Using high-dose (>4 mg/day)    lutein supplements 25 (15) 212 ± 169 AMD    Using low-dose (<.275 mcg/day)    lutein supplements or no    supplements 68 (48) 148 ± 147

References

1. Bernstein PS, et al. Resonance Raman measurement of macular carotenoids in normal subjects and in age-related macular degeneration patients. Ophthalmology 109:1780-87, 2002.
2. Landrum JT, et al. lutein, zeaxanthin & macular pigment. Arch of Biochem & Biophys 385:28-40, 2001.
3. Beatty S, et al. Macular pigment and risk for age-related macular degeneration in subjects from a northern European population. Invest Ophthalmol 42:439-46, 2001.