A new large-scale US study suggests people who eat more leafy green vegetables may reduce their risk of developing glaucoma, which causes vision loss through fluid and pressure build-up in the eye, reports Reuters Health.
Leafy greens, particularly kale and spinach, are high in nitrates, which when converted to nitric oxide in the human body, improve blood flow and keep eye pressure low, researchers suggest.
Based on long-term data for more than 100,000 US adults, those who consumed the most nitrate – mostly from green vegetables like kale and spinach – were 21 per cent less likely than those who ate the least nitrate to develop open-angle glaucoma by the time they were in their 60s and 70s, the report said.
The researchers used data on more than 63,000 women followed from 1984 to 2012 in the Nurses’ Health Study, and more than 41,000 men in the Health Professionals Follow-up Study from 1986 to 2012, Reuters Health said.
The participants were over age 40 at the beginning of the study, had no open-angle glaucoma to start with, reported regular eye tests and completed dietary questionnaires including how often they ate green leafy vegetables like iceberg and romaine lettuces, kale, mustard greens, chard or spinach.
Based on these questionnaires, researchers calculated intakes of nitrate. They found that dark leafy greens were the biggest source of the nutrient, contributing 57 per cent of the nitrate in the participants’ diets.
“Nitric oxide signalling is important for maintaining optimal blood flow, and some evidence suggests that it may also be important for keeping eye pressure low,” lead author Jae H Kang of Brigham and Women’s Hospital and Harvard Medical School in Boston told Reuters Health.