Higher Copper Intake Associated with Reduced Risk of Late AMD

Copper depletion can trigger apoptosis of RPE and retinal cells, contributing to mechanisms of AMD. Photo: Jessica Haynes, OD. Click image to enlarge. Because diet and lifestyle influences weigh heavily on the course of age-related macular degeneration (AMD), efforts to better understand both positive and negative effects can help clinicians educate their patients. Copper, found in foods typical of the Mediterranean diet, plays a critical role in various biological processes, including antioxidant defense and extracellular matrix biosynthesis. In a recent study, researchers investigated the relationship between the intake of copper, as well as iron, zinc, selenium in diet and late AMD, and found that out of all of these elements, increased copper consumption is associated with a reduced risk of late AMD, especially in those between the ages of 70 and 85.In this cross-sectional study, researchers used graded fundus pictures and dietary trace element intake data from 4,996 individuals aged 40 and above from the National Health and Nutrition Examination Survey. Three logistic regression models were used to examine the association between dietary copper, iron, zinc, selenium and late AMD.The levels of copper intake were linked to a reduced risk of late AMD, resulting in odds ratios (OR) of 0.24, 0.38 and 0.37 for model 1, model 2 and model 3, respectively.The levels of dietary iron, zinc and selenium showed an inverse correlation with the prevalence of late AMD in the first model. ORs were the following: iron = 0.92; zinc = 0.88 and selenium = 0.98. However, in models 2 and 3, no significant association was observed between these three elements and late AMD.In subgroup analysis divided by age, there was only a significant inverse correlation observed between late AMD and copper consumption in the group of adults between 70 and 85 years of age.It's been shown that copper plays a major role in modulating oxidative stress, and oxidative stress plays a crucial role in the pathogenesis of AMD. Because of these actions, copper intake may impact AMD by influencing oxidative stress, the authors explained in their BMC Ophthalmology paper. “Reduced levels of copper have been found in the retinal pigment epithelium (RPE) and choroid complex of indi­viduals with AMD,” they wrote. “Intracellular copper depletion triggers apoptosis of RPE and retinal cells. Homocys­teine (Hcy) and homocysteine-thiolactone (HcyTL) are toxic as they can lead to abnormal chelation of the trace element such as copper, thereby altering the structure and function of proteins.”What the authors found interesting was that an increase in Hcy and HcyTL was negatively correlated with plasma copper level, potentially reduc­ing copper-zinc superoxide dismutase amounts, leading to increased oxidative stress and subsequent damage to RPE cells. The Age-Related Eye Disease Study (AREDS) 1 and AREDS 2 study demonstrated similar results, indicating that copper consumption was linked to reduced late-stage AMD risk.However, in adjusted logistic models, no significant association was found between iron, zinc, selenium and AMD. While dietary nutrient intake from the AREDS 1 and AREDS 2 studies showed that higher amounts of iron, magnesium and selenium was linked to decreased late AMD risk, no association was found between zinc and late AMD.“Conversely, the Select Eye Endpoints study revealed that dietary selenium intake showed no association with AMD devel­opment,” the authors explained in their article. “Additionally, a randomized placebo-con­trolled clinical trial on high-dose supplementation with vitamins C and E, beta carotene and zinc for AMD from AREDS suggested that an antioxidant plus zinc supple­ment should be considered for preventing late AMD. The population-based Rotterdam study demon­strated that a high dietary intake of nutrients with anti­oxidant properties including zinc can reduce risk of early AMD.”The inconsistent results from these previous studies may be attributed to differences in the methodology of the present study, as well as differences in dosage between daily intake and additional supplements.The authors suggest that more research into the mechanism linking copper and late AMD development is warranted.Click here for the journal source. Lu Y, Li C, Wu T, Lu P. Association between late age-related macular degeneration and dietary intake of copper, iron, zinc and selenium: a 2005-2008 NHANES cross-sectional observational study. BMC Ophthalmology. May 30, 2025. [Epub ahead of print.]