A new study out of Australia suggests that eating at least one serving of oranges per day can reduce one’s likelihood of developing age-related macular degeneration (AMD) – an incurable, progressively blinding disease – thanks to the fruit’s high content of chemicals called flavonoids.
So, should you go out and buy an entire crate of citrus? Probably, but it’s a bit complicated.
There are two forms of AMD, referred to as wet and dry, that both slowly destroy the eye’s light-sensitive retina via different mechanisms. Mild cases of dry AMD are quite common in people more than 50 years old and typically have little impact. More severe cases of both types are the leading cause of visual impairment in adults, impacting upwards of 196 million people worldwide. Given that there are currently no effective treatments to restore the vision loss it causes, finding out what lifestyle factors help protect against the disease is a high priority for ophthalmologists.
Many past investigations have shown that consuming a diet rich in antioxidants and anti-inflammatory substances reduces the chance of AMD, and several particularly beneficial molecules have been identified: vitamin A, vitamin C, zeaxanthin, and lutein.
The authors of the current paper, published in The American Journal of Clinical Nutrition, sought to examine the poorly understood potential of flavonoids because this class of plant-produced compounds also appears to have potent free-radical scavenging and inflammation-reversing properties.
To do so, they turned to a previously collected dataset of health and lifestyle information for 2,037 Australian adults, aged 49 or above, who were followed for 15 years. Subjects had been examined for signs of AMD at the study onset, year five, year 10, and year 15, and every year they completed questionnaires about how often they consumed different types of food.
After adjusting their statistical analysis for subjects’ consumption of other antioxidants, similarly protective omega fatty acids, and the presence of genetic variations associated with increased risk of AMD, the authors found that risk of any form of AMD went down significantly as overall flavanoid intake went up, a finding that could further explain the established link between general fruit and vegetable consumption and AMD protection.