Changes in Macular Pigment Optical Density and Serum Lutein Concentration in Japanese Subjects Taking Two Different Lutein Supplements

Abstract

Purpose: To investigate macular pigment optical density (MPOD) and serum concentration changes of lutein in Japanese subjects participating in a clinical trial in which two formulations of lutein and zeaxanthin supplements with different physiochemical properties are used.

Methods: Thirty-six healthy volunteers were recruited into this prospective, randomized, parallel-group, double-masked comparative study at a single institute. Two products were used, FloraGLO® (Kemin Japan) and XanMax® (Katra Phytochem). The lutein particle size and zeaxanthin concentrations differed between the formulations. The subjects consumed one of the two supplements for a duration of up to 6 months. MPOD levels were measured by resonance Raman spectrometry at baseline and once a month until the end of the study. Serum lutein concentration was measured at baseline, month 3, and month 6. The subjects were also tested for contrast sensitivity, glare sensitivity, visual acuity, and in addition had a focal electroretinogram measured.

Results: The mean serum lutein concentrations increased significantly after the first three months, but the mean MPOD levels in either supplement group did not show any statistically significant increase. A detailed analysis, however, revealed three response patterns in both groups for the increase of MPOD levels and serum lutein concentration, i.e. "retinal responders", who had an increase of both MPOD levels and serum lutein concentrations (n = 13), "retinal non-responders", who had only increased serum concentrations and no change in MPOD levels (n = 20), and "retinal and serum non-responders", who had neither MPOD level nor plasma concentration increases (n = 3). The subjects with low MPOD levels at baseline appeared to show increased MPOD levels at the 6 month time point upon lutein supplementation (r = -0.4090, p = 0.0133). Glare sensitivity improved in retinal responders in both supplement groups, while there were no remarkable changes in contrast sensitivity.

Conclusions: No statistically significant differences could be detected for MPOD levels and serum lutein concentrations between the two investigated lutein supplement formulations. Responses to lutein supplementation regarding MPOD levels and serum lutein concentrations varied between subjects. Subjects with lower MPOD levels at baseline responded well to lutein supplementation. However, since the number of subjects was low, a further study with more subjects is needed to prove that subjects with low MPOD levels will benefit from lutein supplementation.

Trial registration: UMIN-CTR UMIN000004593.

Conflict of interest statement

Competing Interests: The authors have the following interests: Study supplements were provided free of charge by Koyo Mercantile Co., Ltd., Tokyo, Japan. PSB, WG, and the University of Utah hold the patent for resonance Raman measurement of carotenoids in the human eye (Method and system for measurement of macular pigment levels, U.S. 5873831 A). There are no further patents, products in development or marketed products to declare. This does not alter the authors' adherence to all the PLoS ONE policies on sharing data and materials.

Figures

Fig 1. Flow diagram of the study.

Fig 2. Changes of macular pigment optical density (MPOD) levels in subjects taking two kinds of lutein supplementation.

No significant increase was noted in MPOD levels in either group after six months of supplementation.

Fig 3. Changes in macular pigment optical density (MPOD) levels for three different age ranges in the FloraGLO group (a) and the XanMax group (b).

No significant increase was noted in MPOD levels in either group. The mean MPOD levels in the highest age group were lower than that in the youngest group. (Y; age range from 20 to 34 years old, M; age range from 35 to 49 years old, A; age range of 50 years old and higher).

Fig 4. Changes in serum concentration of lutein for subjects taking two kinds of lutein supplementation.

Serum concentration significantly increased at three months after supplementation, and the high levels continued until the end of supplementation in both groups.

Fig 5. Changes of MPOD levels (a) and serum lutein concentration (b) in three different response pattern groups.

The subjects represented by the solid line showed increases in both MPOD levels and serum lutein concentrations. These subjects were designated “retinal responders”. The subjects represented by the dotted line had no increase in MPOD levels but had increases in serum lutein concentrations. These subjects were designated “retinal non-responders”. The subjects represented by the broken line had no increase in both MPOD levels and serum lutein concentrations. These subjects were designated “retinal and serum non-responders”.

Fig 6. Contrast (a) and glare (b) threshold values in retinal responders.

a. The transverse axis represents the size (visual angle) of the target. No statistically significant improvements were noted across all targets except for 6.3 degrees between baseline and 6 months later. b. Glare sensitivities were significantly improved at the target size of 4.0, 2.5, 1.6 and 1.0 degree between baseline and six months later.