According to a study by the Harvard Medical School in Boston and published in JAMA Ophthalmology individuals who have had a diet rich in nitrates (mainly from green leafy vegetables), they had a lower risk for primary open angle glaucoma (POAG).

The protective effect was particularly evident with those who had initial loss of paracentral visual field (VF) at diagnosis.

The large prospective study included 1,483 incident cases identified from 63.893 women and 41.094 men. The study was conducted from 1984 to 2012, and researchers have conducted evaluation of medical records to confirm the disease.

The average age for the 1,483 cases of POAG was 66.8 years. Individuals who have taken a feeding a diet rich in nitrate-based green leafy vegetables had a 21% lower risk for POAG. The reduction was found in the highest quintile of consumption of nitrate (240 mg / day) compared to the lowest quintile of consumption of nitrate (80 mg / day).The association was even stronger for patients with early loss of VF paracentral.

This subtype of POAG is linked to the dysfunction of ‘autoregulation of blood flow. In particular, those in the highest quintile of consumption had a 44% reduction in risk compared to those in the lowest quintile.

Nitrates are found naturally in green leafy vegetables, as well as other vegetables, such as beets and carrots. The dietary nitrate is an exogenous source of nitric oxide (NO).

POAG seems to be the result of elevated intraocular pressure resulting from impaired autoregulation of blood flow to the optic nerve. Previous studies have suggested that the NO system may play a key role in the pathogenesis of POAG, with alterations in the regulation of ‘NO system in the ocular blood flow.

The authors explain that the way “nitrate-nitrite-NO” may represent an important alternative source of NO in patients with POAG, with a serving of green leafy vegetables making a significant contribution to the production of NO.