Study: Eating grapes may benefit eye health

(Adobe Stock / karandaev)

A team of researchers recently conducted a randomly assigned, controlled human study that found eating grapes for 16 weeks improved key markers of eye health in older adults.

The controlled trial (NCT05064865), published in the scientific journal Food & Function looked at the impact of regular consumption of grapes on macular pigment accumulation and other biomarkers of eye health.1 This is the first human study on this subject, and the results reinforce earlier, preliminary studies where consuming grapes was found to protect retinal structure and function.2

According to a news release from the California Table Grape Association, research has shown that an aging population has a higher risk of eye disease and vision problems. They indicated that key risk factors for eye disease include 1) oxidative stress and 2) high levels of ocular advanced glycation end products (AGEs). AGEs may contribute to many eye diseases by damaging the vascular components of the retina, impairing cellular function, and causing oxidative stress.

“Oxidative stress is a key risk factor for visual impairment and consuming dietary antioxidant-rich foods may help in managing visual impairments,” the researchers wrote in the study.

Dietary antioxidants can decrease oxidative stress and inhibit the formation of AGEs, with possible beneficial effects on the retina, such as an improvement in Macular Pigment Optical Density (MPOD).

The association noted that grapes are a natural source of antioxidants and other polyphenols.

In the study, 34 human subjects consumed either grapes (equivalent to 1 ½ cups of grapes per day) or a placebo for 16 weeks. The grape eaters showed a significant increase in MPOD, plasma antioxidant capacity, and total phenolic content compared to those on placebo. Those who didn’t consume grapes saw a significant increase in harmful AGEs, as measured in the skin.

“Our study is the first to show that grape consumption beneficially impacts eye health in humans which is very exciting, especially with a growing aging population,” said Jung Eun Kim, PhD. “Grapes are an easy, accessible fruit that studies have shown can have a beneficial impact in normal amounts of just 1 ½ cups per day.”

There were no differences in dietary lutein intake, plasma lutein concentration and skin carotenoid status between groups throughout the study.

“Regular intake of grapes may improve eye health in Singapore older adults, specifically in augmenting MPOD, which can be explained by an increase in plasma total antioxidant capacity and phenolic content, and the downregulation of AGEs,” the researchers concluded in the study.

References:

1. Hu W, Zheng R, Feng Y, Tan D, Chan Chung-Tsing G, Su X, Kim JE. Impacts of regular consumption of grapes on macular pigment accumulation in Singapore older adults: a randomized controlled trial. Food Funct. 2023 Sep 19;14(18):8321-8330. doi: 10.1039/d3fo02105j. PMID: 37605542.
2. Patel, A.K., Davis, A., Rodriguez, M.E., Agron, S., Hackam, A.S. (2016). Protective effects of a grape-supplemented diet in a mouse model of retinal degeneration. Nutrition, 32, 384-390. Doi: 10.1016/j.nut.2015.09.017