A large study found that people who ate enough leafy greens had a lower risk of getting primary open-angle glaucoma. A large body of research show the positive impact that good nutrition has on vision health. Eating sufficient amounts of vegetables provides the body with important nutrients.
The eye is made from nutrients. Leafy green vegetables are loaded with vitamin K, magnesium, iron, calcium, beta-carotene, carotenoids and other antioxidants, and the eye nutrients lutein and zeaxanthin.
The study, published in JAMA Ophthalmology, looked retrospectively (after-the-fact) at 41,000+ men and approximately 64,000 women. They were given questionnaires about their nitrate intake. Leafy green vegetables are high in nitrate. Most nitrate is taken in through the diet. Therefore, nitrate intake is a valid indication of leafy green vegetable intake.
Subjects who ate the most nitrate-rich foods had a 20% to 30% decreased risk for developing the most common form of glaucoma called “primary open-angle” (POA). Those who had early paracentral visual field loss had an even lower risk, around 40% to 50% lower.
See the in-depth discussion of this research.
How Much Leafy Greens?
The questionnaire described leafy greens as “iceberg lettuce; romaine lettuce; kale, mustard, or chard; cooked spinach; and raw spinach.” The top leafy green eaters had an average of 1.45 servings per day.
The researchers could not specifically conclude that leafy greens prevent glaucoma. However, previous research has supported the theory that nitric oxide plays a part in the development of glaucoma. These study authors suggested that the eye’s blood flow is increased by dietary nitric oxide. This likely reduces intraocular pressure. High intraocular pressure is often associated with glaucoma.
Editor’s Note: The value of a healthy diet in preventing eye disease cannot be underestimated. A variety of fresh fruits and vegetables each day provides your eyes with the nourishment they need. Ageing individuals have less efficient digestion and lower calorie needs. Having 2 servings of leafy greens per day appears to have a positive effect on the risk of glaucoma. Glaucoma is one of the most common eye disease.
Study: JAMA Ophthalmol. 2016 Mar;134(3):294-303. doi: 10.1001/jamaophthalmol.2015.5601. “Association of Dietary Nitrate Intake With Primary Open-Angle Glaucoma: A Prospective Analysis From the Nurses’ Health Study and Health Professionals Follow-up Study.” by Kang JH et. al.