Curcuma-Based Nutritional Supplements and Risk of Age-Related Macular Degeneration

Medicine Ophthalmology
curcumin age-related macular degeneration nutritional supplements antioxidant anti-inflammatory AMD progression vision loss

Report on Curcuma-Based Nutritional Supplements and the Risk of Age-Related Macular Degeneration

Academic Background

Age-related macular degeneration (AMD) is one of the leading causes of vision loss among elderly individuals, particularly in developed countries. There are two main types of AMD: non-exudative (dry) and exudative (wet). Dry AMD is characterized by gradual degeneration of the macula, while wet AMD involves the growth of abnormal blood vessels, potentially resulting in severe vision loss. While existing treatment methods, such as anti-vascular endothelial growth factor (VEGF) injection therapy, target wet AMD, they cannot completely halt disease progression. Therefore, identifying interventions to prevent or slow down AMD progression is of great significance.

Curcumin, a natural compound extracted from turmeric (Curcuma longa), possesses anti-inflammatory and antioxidant properties. Research suggests that curcumin may mitigate AMD progression by reducing oxidative stress and inflammation. However, prior studies mostly relied on in vitro experiments and animal models, lacking large-scale population studies to validate the potential effects of curcuma-based nutritional supplements (CBNS) in AMD prevention and treatment.

Study Origin

The study was conducted by a research team from Baylor College of Medicine and Stanford University School of Medicine, with primary authors including Amer F. Alsoudi, Karen M. Wai, Euna Koo, Prithvi Mruthyunjaya, and Ehsan Rahimy. The findings were published online on October 24, 2024, in the journal JAMA Ophthalmology.

Study Design and Methodology

Study Design

This was a retrospective cohort study, leveraging data from the TriNetX health research network, which includes de-identified electronic health records from 107 healthcare organizations across 15 countries. The primary objective was to explore the association between CBNS use and the risk of developing or progressing AMD.

Study Population

The study included data collected in June 2024, encompassing 66,804 patients who used CBNS and 1,809,440 patients who did not use CBNS. The participants were either AMD-free individuals aged 50 or older or early-stage non-exudative AMD patients. Propensity score matching (PSM) was employed to control baseline demographics and comorbidities.

Exposure and Outcomes

Exposure was defined as whether patients used CBNS, identified via RxNorm codes from the National Library of Medicine. The primary outcomes included the incidence of non-exudative AMD, exudative AMD, advanced non-exudative AMD or geographic atrophy (GA), blindness, and the need for anti-VEGF therapy.

Data Analysis

PSM was used to balance baseline covariates, and standardized mean differences (SMD) evaluated the balance effectiveness. Relative risks (RR) with 95% confidence intervals (CI) were calculated to compare the incidence rates of outcomes between CBNS users and non-users.

Study Results

Key Findings

  1. Patients Without a History of AMD: Among AMD-free individuals aged 50 and older, those who used CBNS showed substantially lower risks of:

    • Non-exudative AMD (RR, 0.23; 95% CI, 0.21-0.26; p < .001),
    • Advanced non-exudative AMD/GA (RR, 0.11; 95% CI, 0.07-0.17; p < .001),
    • Exudative AMD (RR, 0.28; 95% CI, 0.24-0.32; p < .001),
    • Blindness (RR, 0.46; 95% CI, 0.36-0.59; p < .001),
    • Requiring anti-VEGF therapy (RR, 0.15; 95% CI, 0.13-0.17; p < .001).

  2. Early Non-Exudative AMD Patients: Among early-stage non-exudative AMD patients, CBNS use was associated with significantly lower risks of developing advanced non-exudative AMD/GA (RR, 0.58; 95% CI, 0.41-0.81; p < .001), though the progression to exudative AMD did not show a significant difference.

Subgroup Analysis

Subgroup analyses for patients aged 60 and 70 years or older yielded consistent results, highlighting the protective role of CBNS across different age groups.

Conclusions and Implications

This study demonstrates that CBNS use is significantly associated with a reduced risk of AMD occurrence and progression. While the findings suggest CBNS has potential as an AMD preventive measure, further prospective studies are needed to validate these results and explore the safety and protective mechanisms of CBNS.

Academic and Practical Values

  1. Scientific Contribution: This is among the first large-scale population studies to validate the connection between CBNS use and reduced AMD risk, adding new evidence for turmeric’s application in ophthalmology.
  2. Clinical Application: Should future studies confirm the efficacy and safety of CBNS, it could become an economical and accessible supplementary strategy for AMD prevention and management, particularly in high-risk populations.

Study Highlights

  1. Remarkable Findings: CBNS use shows a significant association with reduced risks of AMD development and progression, especially in individuals with no prior AMD history.
  2. Innovative Methods: By utilizing a large electronic health record database and matching techniques, the study effectively minimized confounding effects, enhancing reliability.
  3. Targeted Research Population: The study included both AMD-free individuals and early-stage AMD patients, providing a comprehensive assessment of CBNS effects.

Limitations

  1. Data Accuracy: The study relied on ICD-10 coding within electronic health records, which may have inaccuracies.
  2. Potential Confounding: Although PSM was used, unmeasured confounding variables, such as lifestyle and dietary habits, may still influence results.
  3. Dosage and Adherence: The study did not standardize CBNS dosages and adherence levels, nor could it confirm sustained use among participants.

Future Research Directions

Future studies should investigate the specific mechanisms of CBNS, validate findings through randomized controlled trials, and evaluate applicability across different ethnic and cultural populations.

Summary

This study provides compelling evidence supporting the potential role of CBNS in reducing the risk of AMD development and progression. Despite limitations, the findings lay the groundwork for future clinical trials. If proven effective, CBNS could become a valuable supplementary tool in AMD management.