A study suggests that increased intake of green leafy vegetables can reduce the risk of glaucoma by up to 30 percent, I4U reports.

"We found those consuming the most green leafy vegetables had a 20 to 30 percent lower risk of glaucoma." Jae Kang, an assistant professor at Boston's Harvard Medical School and lead author of the study said.

The study was published in JAMA Opthalmology.

Researchers from Harvard Medical School led the study that discovered that green leafy vegetables such lettuce, kale, spinach and broccoli are rich in dietary nitrate which can improve the blood flow in the eye.

"These results, if confirmed in observational and intervention studies, could have important public health implications," the researchers said, according to NDTV.

Glaucoma, also called primary open-angle glaucoma (POAG), is an eye condition that causes an abnormal high pressure in the eye and damages the optic nerve.

For the study, researchers followed up more than 100,000 men and women for over 25 years, with nearly 60,000 women from Nurses' Health Study (1984-2012) and around 41,000 men from Health Professionals Follow-up Study (1986-2012).

None of the participants had glaucoma at the start of the study. In subsequent years, 1,483 people developed the eye condition.

Researchers found that those who ate more green leafy vegetables, a cup and half a day, were 20 to 30% less likely to develop glaucoma, as compared to those who consumed the least green vegetables.

"In glaucoma, we think there is an impairment of blood flow to the optic nerve," said Kang.

"And an important factor that regulates blood flow to the eye is the substance called nitric oxide. When you consume the higher amount of green leafy vegetables, you have greater levels of nitric oxide in your body."