Objectives: Oxidative stress is a key risk factor for visual impairment and consuming dietary antioxidant-rich foods may help in managing visual impairments. However, limited studies investigated the effect of dietary antioxidants-rich food including grapes on eye health in older adults. The objective of this study is to assess the effects on macular pigment accumulation of regular consumption of grapes in Singapore older adults.
Methods: This was a 16-week, double-blind, randomized, placebo-controlled trial. Singapore older adults were randomized into regularly consuming either 46 g/day of freeze-dried table grape powder (intervention group) or the same amount of placebo powder (placebo group). Macular pigment optical density (MPOD), skin carotenoids and advanced glycation end products (AGEs) status and dietary lutein intake were assessed every 4-week and plasma lutein concentration and total antioxidant capacity were measured every 8-week.
Results: Significant time effect (p = 0.0068) was observed for MPOD and this is largely attributed to the improvement in MPOD for the intervention group, as significant increase was observed only in this group (week 0: 0.56 ± 0.04 D.U.; week 16: 0.61 ± 0.04 D.U., p < 0.01). Additionally, significant increase in total antioxidant capacity (week 0: 0.26 ± 0.13 mM; week 16: 0.36 ± 0.20 mM, p < 0.01) was observed for the intervention group only. In contrast, significant increase in skin AGEs status was observed in the placebo group (week 0: 2.47 ± 0.24; week 16: 2.99 ± 0.12, p < 0.05) while this was mitigated in the intervention group. There were no differences in dietary lutein intake, plasma lutein concentration and skin carotenoids status between groups throughout the study.
Conclusions: Regular intake of grapes may improve eye health in Singapore older adults, specifically in augmenting MPOD, which can be explained by increase in total antioxidant capacity and downregulation of AGEs.
Funding Sources: The California Table Grape Commission
