An Australian team of scientists have found that people who regularly eat oranges have a lower risk of developing age-related macular degeneration than those who do not regularly eat them. The study followed over 2,000 adults over 15 years and was published in the American Journal of Clinical Nutrition. A summary of the study is free to read online, and it can be accessed in full with an Oxford Academic account.
The team of scientists, from the Westmead Institute for Medical Research, recruited adults over 50 years of age, to follow over a 15 year period. Although many studies of this type have focused on the role of vitamins C, E and A on the eyes, this study focused particularly on flavonoids, found in oranges. Data was collected from the Blue Mountains Eye Study, which began in 1992 and is seen as a benchmark population-based study. Food intake was assessed, using a food-frequency survey and estimates of the flavonoid content of food were gathered, using the USDA Flavonoid, Isoflavone and Proanthocyanidin databases. The progression of age-related macular degeneration (AMD) was measured using retinal photographs.
Flavonoids are found in most fruit and vegetables. They are powerful anti-oxidants which also offer anti-inflammatory properties in the immune system. Foods that contain flavonoids include tea, red wine, apples and oranges, but only the oranges showed a significant effect in protecting against AMD. Eating one orange a week could offer some protection for the eyes against developing the disease, but the most significant benefits were shown for the people who ate an orange a day.
The study authors acknowledged the need for further cohort studies to investigate the link.
AMD affects the central part of the retina of the eye, known as the macula. It causes changes to the macula, which means that people may see a blank spot when looking directly at something. It is not a painful condition and it does not cause people to lose all of their sight. There are two types of AMD. Dry AMD develops slowly and gradually causes change in the vision. It is the most common type of the disease. Wet AMD can change the vision very quickly. It is caused by the cells of the macula not working correctly. To compensate, the body starts growing new blood vessels which can then cause swelling and bleeding underneath the macula which causes scarring. These new blood vessels and scarring then damage the central vision, leading to a blank centre in the sight. Peripheral (around the edge of your sight) vision is not affected.
Symptoms of AMD include:
Difficulty reading small print, even if using reading glasses
Straight lines seem to look distorted and wavy
Your vision seems not to be as clear as it once was
If you suspect you may have AMD, then you should book an appointment with an optometrist as soon as possible.
If your vision changes very quickly, then the need to see an eye health professional is more urgent. If there is a sudden change of sight, then it is possible to attend A&E at the nearest hospital. If you are diagnosed with AMD by your optometrist, then they will refer you to a consultant at the hospital.
Gopinath, B., et al., Dietary flavonoids and the prevalence and 15-y incidence of age-related macular degeneration, July 2018, The American Journal of Clinical Nutrition, Vol. 108, issue 2, pp381-387