Harvard Health Letter

Harvard researchers: Fight glaucoma with leafy green vegetables

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Think about this the next time you fill your plate with kale or spinach: a study published in JAMA Ophthalmology Jan. 14, 2016, found that boosting leafy green vegetable intake is associated with a reduced risk of developing glaucoma, a leading cause of blindness.

Harvard researchers analyzed the dietary information reported by more than 100,000 men and women in two long-term studies, each lasting more than 25 years. Those who ate the most leafy greens had a risk of developing glaucoma that was 20% to 30% lower than that of those who ate the least. What's the link? Glaucoma causes damage to the optic nerve, through increased pressure from fluid in the eye or impaired blood flow to the optic nerve. Leafy greens are loaded with nitrate, which the body converts to nitric oxide. "Nitric oxide is important for maintaining optimal blood flow, and possibly for keeping eye pressure low," speculates Dr. Jae Hee Kang, the lead author of the study and a Harvard Medical School assistant professor. The study doesn't prove that leafy greens reduce glaucoma risk; it only shows an association between the two. Eating leafy greens is also linked to lower rates of inflammation, cancer, heart disease, and even macular degeneration.