Abstract
Purpose: :
Dietary supplementation with carotenoids may have a role in preventing age–related macular degeneration and there are numerous formulations of lutein/zeaxanthin on the market. This study was performed to assess the effect of a high–dose lutein supplement on macular pigment optical density (MPOD), in a large group of healthy subjects.
Methods: :
324 healthy volunteers were recruited (mean age 39+/–8.7 years). Subjects with ocular pathology were excluded. MPOD was measured in the right eyes of all subjects using heterochromatic flicker photometry (HFP) and a 2–wavelength (488nm & 514nm) fundus autofluorescence (AF) technique using a modified Heidelberg Retinal Angiograph (HRA). Subjects were asked to take a daily vitamin supplement, "Macuvite" (Springfield®), consisting of 18mg lutein (in its free form) and 2.4mg of zeaxanthin for 6 months. MPOD was measured at 3 and 6 months. Serum macular pigment levels (by HPLC) and compliance by pill count was measured.
Results: :
At baseline, MPOD levels exhibited a normal distribution with a mean of 0.44 (SD 0.21, range 0.04 to 1.25) using HFP and 0.41 (SD 0.15, range 0.03 to 0.85) using AF (at half–degree eccentricity). At 3 months following supplementation, there was no increase in MPOD levels using both HFP and AF methods of assessment. After 6 months of supplementation, a marginal increase in MPOD was seen using both methods (mean increase: 0.025+/–0.16 using HFP, 0.015+/–0.058 using AF), which was statistically significant (ttest: p=0.018 HFP, p<0.001 AF). Serum lutein levels were significantly raised from baseline at the 3–month measurement (mean increase 174%, p=0.0002), and compliance was good (mean 90.1+/–12.4% of vitamins taken).
Conclusions: :
High dose carotenoid supplementation resulted in no rise in MPOD at 3 months and a marginal rise at 6 months, despite significant increases in serum carotenoid levels. This suggests that (a) future supplement studies need to be long–term and (b) the formulation of supplementation may be important. Simply increasing serum carotenoid levels does not necessarily mean an increase in macular pigment optical density.
Keywords: macular pigment • carotenoids/carotenoid binding proteins • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials