How food choices may affect non-refractive visual impairment

(Image Credit: Adobestock/Daniel Vincek)

A Chinese study¹ identified a positive association between the dietary inflammatory index (DII) and non-refractive visual impairment among US populations, that is, the loss of vision resulting from ocular diseases and not the shape of the eye, according to the coauthors.

Yudie Hu, MD, is from the Department of Breast, The First Hospital of Hunan University of Chinese Medicine, Changsha, China; Jiang Zheng, MD, is from the Department of Ophthalmology, The First Affiliated Hospital of Jinan University, Jinan University, Guangzhou, China; and Lun He, MD, is from the Department of Ophthalmology, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou.

The authors explained that the DII evaluates the potential for development of inflammation based on an individual’s diet. It quantifies the inflammatory effects of foods and nutrients eaten^2,3 and assigns them a score that reflects the impact on inflammatory biomarkers such as C-reactive protein (CRP), interleukin-1β (IL-1β), IL-6, white blood cell counts, and tumor necrosis factor-alpha (TNF-α).^2-6

“Utilized in epidemiological studies, the DII has shed light on the association between diet and inflammation-related diseases, including cardiovascular disease, cancer, and metabolic syndrome.^7-10 By assessing patients’ dietary patterns and the associated inflammatory potential, researchers can discern the role of diet in chronic inflammation and associated health outcomes, they commented.

The investigators used National Health and Nutrition Examination Survey (NHANES) data in a cross-sectional study to determine the association between DII and non-refractive visual impairment from diseases other than cataract and age-related macular degeneration.^11,12

They included patients who presented with a visual impairment, that is, a visual acuity (VA) in the better-seeing eye that was below 20/40. Those with a VA in the better-seeing eye corrected to 20/40 or better through automated refraction were classified with an uncorrected refractive error, the others were classified with a non-refractive visual impairment.

Dietary intake data were obtained from 521 participants about the types and quantities of food and drinks consumed in the 24 hours before the interview; that information then was used to calculate the DII.^13,14 Of those participants, 106 had non-refractive visual impairment. The authors considered 45 food parameters that were assessed using specific biomarkers (IL-1β, IL-4, IL-6, IL-10, TNF-α, and CRP) and multiplied by individual food parameter consumption to generate a patient’s overall score.

Inflammation and vision

A positive association was seen between the DII scores and the prevalence of non-refractive visual impairment (odds ratio = 1.277, 95% confidence interval = 1.017–1.603, P < 0.05) in the US.

In commenting on the findings, the investigators said, “The DII, a robust tool for exploring the relationship between diet and diseases, has been shown to be associated with the levels of circulating inflammatory biomarkers, including IL-1β, IL-6, and TNF-α. Taken together, alterations in systemic inflammation levels induced by the pro-inflammatory diets may influence the onset and progression of ocular diseases, ultimately contributing to non-refractive visual impairment, which offers a plausible interpretation for our findings.”

The authors advised that a prospective cohort study be conducted to confirm this relationship and elucidate the underlying mechanisms.

References:

1. Hu Y, Zheng J, He L, Hu J, Yang Z. Association between dietary inflammatory index and visual impairment among adults in the NHANES 2005–2008. Sci Rep. 2024;14:30668.

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14. Zhou N, Xie A-P, Liu Q, et al. The dietary inflammatory index and its association with the prevalence of hypertension: A cross-sectional study. Front Immunol. 2022;13:1097228. https://doi.org/10.3389/fimmu.2022.1097228