New findings from a recent study published in Clinical Nutrition evaluated whether pro- or anti-inflammatory diets impact the incidence of cataracts, age-related macular degeneration (AMD), and open-angle glaucoma (OAG).
Give me some background first.
As inflammation is involved in the pathogenesis of cataracts, AMD, and potentially OAG, a Dutch research team measured the inflammatory potential of diet using the dietary inflammatory index (DII).
To note, the DII was originally created to offer a quantitative tool for measuring the role of diet in inflammation-mediated health outcomes.
Now, talk about the study.
In this prospective, population-based study, investigators selected patients above 45 years of age from the Rotterdam Study.
The Rotterdam Study is a prospective cohort study that has been ongoing since 1990 and targets a variety of systemic diseases to elucidate the causes of diseases in the elderly to identify and study potential risk factors.
Investigators used data from 1991 on participants that underwent extensive eye examinations every 4-5 years.
At baseline, blood samples and dietary data—collected via food frequency questionnaires—were reported.
Tell me more.
Of the total 7,436 participants free of eye diseases at baseline, 4,036 developed eye diseases during the follow-up period.
The incidence of eye diseases was as follows:
- Cataract: 2,985
- Early-intermediate AMD: 891
- Late AMD: 81
- OAG: 169
How did they measure the inflammatory potential of diet?
The DII was adapted based on the responses to the food frequency questionnaires. Additionally, serum inflammation markers were assessed as potential mediators.
The adapted DII (aDII) ranged from -4.26 (i.e., anti-inflammatory) to 4.53 (i.e., pro-inflammatory).
Findings?
A higher aDII was significantly associated with increased inflammation, and every point increase in the aDII was associated with a 9% increased risk of cataracts (odds ratio [OR] 1.09, 95% confidence interval [CI] 1.04-1.14).
A higher neutrophil-lymphocyte ratio (NLR)—a marker of subclinical inflammation—was associated with an increased risk of cataracts and AMD.
Additionally, complement component 3c (C3c) and systemic immune-inflammation index (SII) were associated with increased risks of cataracts and late AMD, respectively.
Expert opinion?
According to the study authors, “We were able to show that a more pro-inflammatory diet was not associated with the risk of preliminary AMD (or ‘age-related changes’), but was associated with a higher risk of more advanced stages of AMD.”
“Moreover, we confirmed previous findings that (late) AMD patients have higher NLRs than those without AMD,” they added.
Limitations?
One of the key limitations of this study is the necessity to adapt the DII to missing data, introducing the potential for influencing the reported associations.
Additionally, the cohort was mainly of European descent, meaning the results may not be translatable to other ethnicities.
Take home.
These findings indicate that a pro-inflammatory diet was associated with an increased risk of cataracts and more severe AMD.
Of note, these associations were partly mediated by NLR, a marker that highlights the balance between acute- and chronic inflammation and the adaptive immune system.
Significance?
These findings could aid eyecare practitioners managing AMD patients to substantiate current recommendations for maintaining a healthy lifestyle and eating a nutrient-dense, anti-inflammatory diet to prevent blindness.