Ultra-processed Foods Linked to Higher Glaucoma Risk

In a recent study published in the journal Nutrients, researchers investigated the association between consumption of ultra-processed foods (UPF) and the glaucoma risk among Spanish university graduates.

Background Glaucoma is a leading cause of lifelong blindness globally, characterized by the gradual loss of retinal ganglion cells. Elevated intraocular pressure, advanced age, non-Caucasian race, and family history increase the risk of glaucoma. However, modifiable environmental factors such as nutrition, exercise, and lifestyle are increasingly recognized as contributors to its development. Alternative and complementary therapies for glaucoma have gained popularity, but further research is needed to explore their therapeutic potential fully. Nutrition is gaining scientific attention due to the prevalence of UPF rich in salt, sugar, and fat. Previous studies suggest a link between diet and glaucoma risk, although the relationship remains unclear. More research is needed to translate these findings into clinical care practices.

About the study In this observational, prospective cohort study, researchers examined whether consuming UPF increases the risk of glaucoma among university graduates in Spain.

The study included 19,255 participants from the Seguimiento Universidad de Navarra (SUN) Project (60% women, mean age 38 years). Researchers followed the participants for an average of 13 years through biennial online or mail questionnaires. The baseline questionnaire (Q0) collected data on sociodemographic factors, physical measurements, dietary practices, lifestyle habits, and comorbidities. Follow-up questionnaires were sent every two years (Q2 to Q20) to assess changes in diet, lifestyle, and medical conditions and monitor disease incidences. Updated data was obtained through the Q10 study questionnaire.

Food-frequency questionnaires (FFQ) were used to assess dietary intake, and the NOVA food classification was used to determine UPF consumption. Glaucoma diagnosis was determined by asking participants if they had ever received a glaucoma diagnosis from an ophthalmologist. Additionally, the researchers validated self-reported diagnoses in 150 individuals based on the European Glaucoma Society guidelines at baseline and a two-year interval during follow-up.

Individuals with glaucoma or ocular hypertension at baseline and those with energy intake outside predetermined limits were excluded from the study. Cox regression models were used to calculate hazard ratios (HR), adjusting for sociodemographic, lifestyle, dietary, and medical history variables. Sociodemographic variables included age, sex, educational attainment, and body mass index. Lifestyle and dietary variables included total calorie intake, adherence to the Mediterranean diet, physical activity, smoking status, caffeine and ethanol consumption, omega-3: omega-6 ratio, and specific diets. Comorbidities included hypertension, cardiovascular disease, diabetes, and cancer.

Results and discussion During follow-up, 230 cases of glaucoma were identified, accounting for 176,963 person-years of observation. Participants with the highest UPF intake were younger and consumed more ethanol and coffee, with higher calorie intake. After adjusting for covariates, individuals with the highest UPF intake (more than four servings per day) had a higher glaucoma risk (HR 1.8) compared to those with the lowest UPF intake.

Subgroup analysis revealed statistically significant associations based on participant age and dietary omega-3: omega-6 ratio. However, the relationship between UPF consumption and incident glaucoma was observed primarily in older, physically active, non-smoking males aged ≥55 years with a low omega-3: omega-6 fatty acid ratio and total calorie intake. Sweets were associated with a significantly higher risk of glaucoma incidence (HR 1.5). Validation of self-reported and clinical case diagnoses showed strong agreement, with high sensitivity and specificity, particularly for open-angle glaucoma.

High UPF intake can lead to elevated blood glucose levels, oxidative stress, and inflammation, with sweets playing a significant role. These processed foods have lower nutritional density and a higher glycemic impact, contributing to oxidative stress and inflammation. Exposure of the retina to reactive oxygen species (ROS) increases inflammation and glaucoma risk. High UPF consumption can also lead to weight gain, endothelial dysfunction, elevated blood glucose levels, oxidative stress, and inflammation. The relationship between UPF intake and low-grade inflammation is not fully understood but is likely due to their potent pro-inflammatory properties. UPFs negatively impact dietary quality by containing high levels of added sugars, trans fats, and salt, displacing nutrients when substituted for healthier options such as fruits and vegetables.

Conclusions Overall, the study found that individuals with the highest UPF consumption had a higher risk of developing glaucoma compared to those with the lowest UPF consumption. Notably, sweets were independently associated with increased glaucoma risk. These findings highlight the importance of health monitoring and controlling UPF intake, especially high-sugar varieties, to reduce incident glaucoma cases.

Given the increasing prevalence of UPF consumption, healthcare professionals should promote food patterns emphasizing unprocessed or minimally processed foods. Additionally, several governments have implemented policies such as front-of-package labeling, taxes on unhealthy foods, restrictions on advertising, and promotion of healthier alternatives to discourage UPF consumption.

For more information: Is Ultra-Processed Food Intake Associated with a Higher Risk of Glaucoma? A Prospective Cohort Study including 19,255 Participants from the SUN Project, Nutrients 2024, https://doi.org/10.3390/nu16071053