Researchers examined if dietary nitrate intake through leafy greens, beetroot, and other vegetables and foods are associated with the incidence of age-related macular degeneration.
Age-related macular degeneration (AMD) is a leading cause of irreversible visual impairment in older people. AMD occurs when part of the retina, the macula, starts to fail. Nitrate, found in many vegetables and other food, can be highly beneficial. When consumed, nitrate foods create a gas called nitric oxide. It is thought that too much or too little nitric oxide is related to the cause of several diseases, including AMD.
In a study published by the Academy of Nutrition and Dietetics, researchers examined over 2,000 Australian participants over 49 years old to determine the association between dietary nitrate intake and age-related macular degeneration. This was a population-based cohort study, called The Blue Mountains Eye Study. The researchers followed the participants for 15 years (1992-1994 to 2007-2009).
The researchers conducted baseline studies and then follow-up studies five, ten, and fifteen years later. Each participant provided dietary information through a food frequency questionnaire. With this information, the researchers examined the levels of nitrate within each vegetable on record. Each participant also had photos taken of their retinas so that researchers could examine the prevalence of AMD.
The results showed that participants who consumed around 100-142 mg of vegetable nitrates per day were less likely to develop AMD compared to people who ate less than 69 mg daily. Specifically, the participants who ate 100-142 mg of vegetable nitrates daily were 35% less likely to develop AMD. Leafy greens and beetroots are the best sources of dietary nitrate to consume. This study was strong due to its overall design, food frequency questionnaire, and nitrate database.
The authors conclude saying, “if our findings are confirmed, incorporating a range of foods that are rich in dietary nitrate such as [leafy greens] and beetroot could represent a simple strategy to enhance nitric oxide status, thereby potentially minimizing early AMD risk”.
Written by Laura Laroche, HBASc, Medical Writer
- Eating leafy greens could help prevent macular degeneration. 2018, https://www.westmeadinstitute.org.au/news-and-events/2018/eating-leafy-greens-could-help-prevent-macular-deg, assessed 6 Nov. 2018.
- Gopinath, Bamini. et al. “Association of Dietary Nitrate Intake with the 15-Year Incidence of Age-Related Macular Degeneration.” Academy of Nutrition and Dietetics.March 1, 2018. 1-4. Online.