Antioxidant NAC May Protect Against AMD

A new study published in Ophthalmology suggests that N-acetylcysteine (NAC) may reduce the risk of AMD. The retrospective cohort study, using data from the Taiwan National Health Insurance Research Database, found NAC users had a significantly lower risk of AMD, with a dose-response relationship observed. Further research is warranted to confirm these findings. Photo: Spring Valley. Click image to enlarge. Age-related macular degeneration (AMD) continues to be a public health concern in aging populations, the global prevalence of which is estimated to reach 288 million by 2040. Late stages of the disease impose substantial costs and societal burdens on patients who are suffering from vision loss. In this realm, the sulphur-containing antioxidant N-acetylcysteine (NAC) has gained attention because it acts as both a free radical scavenger and a precursor of glutathione—a tripeptide integral to the cellular defense system. A group of researchers from Taiwan have released results of a new study, published in Ophthalmology, that seems to confirm prior theories on NAC’s ability to reduce oxidative stress, therefore potentially protecting against AMD. The retrospective cohort study comprised data from the Taiwan National Health Insurance Research Database, which effectively represents the entire population of the country, according to the study authors. Propensity score matching was applied to ensure comparable baseline demographics between oral NAC users and non-users, ultimately including 5,234 in each group. Results showed that NAC users exhibited a significantly lower hazard ratio (HR) of AMD than non-users (HR: 0.19). This was observed for both dry (HR: 0.19) and wet (HR: 0.31) AMD. Researchers also identified a dose-response relationship, with higher cumulative doses of NAC associated with a greater reduction in the risk of AMD and dry AMD. NAC may have an anti-inflammatory effect in the retina, as one of its primary mechanisms involves suppressing proinflammatory cytokines, which are elevated in AMD. “Given that inflammation and oxidative stress are tightly interconnected in the pathogenesis of AMD, the ability of NAC to modulate both processes highlights its potential as a therapeutic agent for reducing the inflammatory burden in AMD and preserving retinal function,” the authors wrote in their study. In the researchers’ sub-analyses of NAC doses, only patients with high cumulative daily dose levels demonstrated a significant reduction in the risk of developing dry AMD, whereas no significant effects were observed in the lower dosage groups. “This indicated that substantial doses or prolonged NAC use may be necessary to achieve its potential protective effects against AMD,” they wrote. “Further studies are warranted to confirm these findings and clarify the dose-response relationship.”The authors were unable to make a definitive conclusion regarding a significant link for wet AMD due to the sensitivity analysis, which was limited to individuals over 60 and 70. “This uncertainty is likely due to the small number of wet AMD cases” in the sample, they wrote. Additionally, the study has potential limitations due to its reliance on an administrative database that lacked detailed clinical information on patients’ lifestyles and susceptibility to incorrect ICD codes, noted the authors.While the researchers found much that is illuminating in their data, they acknowledged in their paper that “further investigation through large, prospective studies is imperative to substantiate the therapeutic potential of NAC in this context.”Click here for the journal source. Tsai, Hou-Ren et al. Oral acetylcysteine and the risk of age-related macular degeneration: A retrospective cohort study. Ophthalmology. October 6, 2025. [Epub ahead of print.] This article was developed by the editorial staff in conjunction with experts in the field. In the process, AI may have been among the editorial tools used to meet the goals of human editors, who approved all content.