Leafy green vegetables have long been associated with health benefits because they are brimming with minerals, vitamins and fibers that protect the body from a range of diseases such as heart disease and diabetes.
Now, a new study offers new evidence that supports diets rich in greens. Researchers have found a link between high intake of leafy green vegetables and reduced risk for the world's leading cause of irreversible blindness.
Primary open-angle glaucoma, or POAG, is a progressive condition that often occurs in adults over 50 years of age. It affects about 1 percent of the U.S. population.
POAG does not initially exhibit swelling or other symptoms that indicate a problem. The pressure in the eye gradually increases and the cornea adapts without swelling. Those affected often only know they have the problem once their vision becomes impaired. Once this occurs, the damage is often already irreversible.
A team of researchers, however, have identified a natural way of reducing risks of developing the condition. They have found that adopting a diet high in nitrate, primarily from green leafy vegetables, can significantly cut the likelihood of developing POAG.
Nitrates are naturally present in green leafy vegetables such as kale, spinach, broccoli and cabbage. They can be found in other vegetables as well such as carrots and beets.
For the study published in JAMA Ophthalmology on Jan. 14, Jae Kang from Harvard Medical School and colleagues followed 63,893 women and 41,094 men. Of these, 1,483 developed POAG during the follow-up period.
The researchers found that the participants who reported greater consumption of leafy green vegetables, which resulted in increased nitrate levels, had up to 30 percent decreased risks of developing the eye problem.
This group of participants also had between 40 and 50 percent reduced risk of developing a sub-type of the condition known as early paracentral visual field (VF) loss, which is linked to dysfunction in blood flow autoregulation.
Kang and colleagues said the results of their study could have important implications for POAG once association between reduced POAG risk and increased intake of nitrate and green leafy vegetables is confirmed.
"Higher dietary nitrate and green leafy vegetable intake was associated with a lower POAG risk, particularly POAG with early paracentral VF loss at diagnosis," the researchers wrote in their study.