Zeaxanthin Supplementation Raises MPOD, Helps Cones

CHICAGOZeaxanthin supplementation can increase macular pigment ocular density (MPOD) and provide distinct visual benefits by improving the foveal cones, according to recent research from Rosalind Franklin University of Medicine and Science, Chicago Medical School. The findings were published in the November issue of Optometry (2011; 82(11):667-680.e6).

In the one-year prospective, controlled study, 57 older men and three older women with mild-to-moderate age-related macular degeneration (AMD) were randomly assigned to take either 8mg zeaxanthin (n=25), a combination of 8 mg zeaxanthin and 9 mg lutein (n=25) or a placebo (n=10). Researchers measured MPOD, low- and high-contrast visual acuity, foveal shape discrimination, glare recovery, contrast sensitivity function and other visual and functional parameters.

They found no intergroup differences in three major AMD risk factors: age, smoking and body mass index (BMI), nor did they find differences in disease duration and Visual Function Questionnaire results. Randomization resulted in equal MPOD variance and MPOD increasing in each of the 3 groups from 0.33 density units (du) (0.17 SD) baseline to 0.51 du (0.18 SD) at 12 m, (P = 0.03), but no between-group differences (Analysis of Variance; P = 0.47). Researchers noted detailed high-contrast visual acuity improved by 1.5 lines in the zeaxanthin only group. Also, Retina Foundation of the Southwest shape discrimination sharpened from 0.97 to 0.57 (P = 0.06, 1-tail) in this group, which also had a larger percentage of patients experienceing clearing of their KVF central scotomas (P = 0.057).

Researchers concluded zeaxanthin supplementation elevated foveal MPOD in a similar manner to lutein supplementation, but zeaxanthin alone also provided distinct vision benefits via improvements in the foveal cones. On the other hand, lutein tended to improve rod-related vision. The combination zeaxnathin-lutein supplementation did not raise MPOD as the individual carotenoids did, a result attributed to carotenoid competition in either the intestines, liver or retina.