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JAMA Ophthalmol. 2016 Mar 1;134(3):294-303. doi: 10.1001/jamaophthalmol.2015.5601.

Association of Dietary Nitrate Intake With Primary Open-Angle Glaucoma: A Prospective Analysis From the Nurses' Health Study and Health Professionals Follow-up Study.

Author information

  • 1Channing Division of Network Medicine, Department of Medicine, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts.
  • 2Channing Division of Network Medicine, Department of Medicine, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts2Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts3Department of Epidemiology, Harvard.
  • 3Channing Division of Network Medicine, Department of Medicine, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts4Department of Biostatistics, Harvard School of Public Health, Boston, Massachusetts.
  • 4Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital Research Institute, Boston.
  • 5Glaucoma Service, Massachusetts Eye and Ear Infirmary, Boston.
  • 6Channing Division of Network Medicine, Department of Medicine, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts6Glaucoma Service, Massachusetts Eye and Ear Infirmary, Boston.

Abstract

IMPORTANCE:

Nitric oxide signaling alterations in outflow facility and retinal blood flow autoregulation are implicated in primary open-angle glaucoma (POAG). Nitric oxide donation has emerged as a POAG therapeutic target. An exogenous source of nitric oxide is dietary nitrates.

OBJECTIVE:

To evaluate the association between dietary nitrate intake, derived mainly from green leafy vegetables, and POAG.

DESIGN, SETTING, AND PARTICIPANTS:

We followed up participants biennially in the prospective cohorts of the Nurses' Health Study (63 893 women; 1984-2012) and the Health Professionals Follow-up Study (41 094 men; 1986-2012) at each 2-year risk period. Eligible participants were 40 years or older, were free of POAG, and reported eye examinations.

EXPOSURES:

The primary exposure was dietary nitrate intake. Information on diet and potential confounders was updated with validated questionnaires.

MAIN OUTCOMES AND MEASURES:

The main outcome was the incidence of POAG and POAG subtypes; 1483 cases were confirmed with medical records and classified into subtypes defined by intraocular pressure (IOP) (≥22 or <22 mm Hg) or by visual field (VF) loss pattern at diagnosis (peripheral loss only or early paracentral loss). Cohort-specific and pooled multivariable rate ratios (MVRRs) and 95% CIs were estimated.

RESULTS:

During 1 678 713 person-years of follow-up, 1483 incident cases of POAG were identified. The mean (SD) age for the 1483 cases was 66.8 (8.3). Compared with the lowest quintile of dietary nitrate intake (quintile 1: approximately 80 mg/d), the pooled MVRR for the highest quintile (quintile 5: approximately 240 mg/d) was 0.79 (95% CI, 0.66-0.93; P for trend = .02). The dose response was stronger (P for heterogeneity = .01) for POAG with early paracentral VF loss (433 cases; quintile 5 vs quintile 1 MVRR = 0.56; 95% CI, 0.40-0.79; P for trend < .001) than for POAG with peripheral VF loss only (835 cases; quintile 5 vs quintile 1 MVRR = 0.85; 95% CI, 0.68-1.06; P for trend = .50). The association did not differ (P for heterogeneity = .75) by POAG subtypes defined by IOP (997 case patients with IOP ≥22 mm Hg: quintile 5 vs quintile 1 MVRR = 0.82; 95% CI, 0.67-1.01; P for trend = .11; 486 case patients with IOP <22 mm Hg: quintile 5 vs quintile 1 MVRR = 0.71; 95% CI, 0.53-0.96; P for trend = .12). Green leafy vegetables accounted for 56.7% of nitrate intake variation. Compared with consuming 0.31 servings per day, the MVRR for consuming 1.45 or more servings per day was 0.82 for all POAG (95% CI, 0.69-0.97; P for trend = .02) and 0.52 for POAG with paracentral VF loss (95% CI, 0.29-0.96; P for trend < .001).

CONCLUSIONS AND RELEVANCE:

Higher dietary nitrate and green leafy vegetable intake was associated with a lower POAG risk, particularly POAG with early paracentral VF loss at diagnosis.

PMID:
26767881
[PubMed - in process]
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