Foods rich in flavonoids may protect against age-related macular degeneration (AMD), the leading cause of blindness in older adults, a new study suggests.
The intake of certain flavonoids found in abundance in a range of fruits, vegetables, and even beverages such as tea could have a protective effect against the development of late-stage AMD, lead researcher and associate professor Bamini Gopinath, PhD, from the Westmead Institute for Medical Research and the University of Sydney, told MD Magazine®.
The data did not show a relationship between other food sources protecting the eyes against AMD, the researchers said. One fruit stood out in the long haul.
“Habitual consumption of oranges, one of the food groups that contributes to flavonoid intake in the diet, reduced the risk of developing macular degeneration over 15 years,” Gopinath said.
People who ate at least 1 serving of oranges every day had more than a 60% reduced risk of developing late macular degeneration in that time period, the study found.
Even eating an orange once a week seemed to offer significant benefits.
Previous research has focused the effects of common antioxidants including vitamins C, E and A, and carotenoids on the risk and progression of AMD. Studies of phytochemicals, such as flavonoids, which have antioxidant and anti-inflammatory properties, have been limited, the researchers wrote.
To investigate, Gopinath and a team from Westmead, analyzed data from a population-based cohort study conducted in intervals starting in 1992-1994 and ending in 2007-2009.
The study measured diet and lifestyle factors against health outcomes and a range of chronic diseases. The team assessed 2856 adults aged 49 and older for AMD prevalence and followed 2037 of them 15 years later to consider incidence of the disease. The data showed significant and protective associations between the intake of total flavonoids and AMD prevalence as well as associations between total intake of flavonals and flavanones, two types of flavonoids, and prevalence.
The researchers also found “modest” associations between classes of flavonoids including flavones, flavanones and hesperidin and the risk of incident late AMD 15 years later.
“Increasing intake of total flavonoids, flavonols and flavanones were all associated with reduced prevalence of any AMD signs,” Gopinath said. “In terms of 15-year incidence of AMD, only intake of flavanones showed a marginally significant protective effect against late AMD,” she said.
That’s where the power of oranges comes in.
“Our research suggests that particular flavonoid classes, that is, flavanones, could exert a greater protective effect against the development of AMD,” Gopinath said. “Oranges are rich in a specific type of flavanone which could help explain its effect, but other studies are needed to clarify this further.”
Asked why flavonoids might exhibit such positive associations, Gopinath cited their characteristics.
“We can speculate that flavonoids have antioxidant and anti-inflammatory properties and so the intake of these dietary compounds is likely to have a beneficial impact on macula health,” she said.
What do the findings mean for formulating an eye-protecting diet?
“To maintain optimal macula health and reduce risk of developing AMD, it’s important to include a lot of dark leafy green vegetables, fruits, such as oranges, 2 or more servings of fish per week, and to try and eat low glycemic index (GI) rather than high GI foods,” Gopinath said.
She noted that preventing AMD is important because the condition, which causes loss in the center of the field of vision, substantially impacts a person’s functioning and health. Currently there is no cure.
“Minimizing the risk of this devastating condition remains an important area of research,” Gopinath said. “I don’t think it’s ever too late to gain benefits from a healthy diet, that also incorporates plenty of food groups with flavonoids in it.”
The study, “Dietary flavonoids and the prevalence and 15-y incidence of age-related macular degeneration,” was published online in the American Journal of Clinical Nutrition.