AMD - an orange a day protects against this eye disease. Why do you think that is?

2020-02-03

People who regularly eat fresh oranges have a significantly lower risk of developing age-related macular degeneration (AMD), an incurable disease affecting a tiny area of the retina at the back of the eye.

Q&As Vision & Hearing

A study published in August 2018 has shown that people who regularly eat fresh oranges have a significantly lower risk of developing age-related macular degeneration (AMD), an incurable disease affecting a tiny area of the retina at the back of the eye.

Scientists at Australia’s Westmead Institute for Medical Research monitored around 2000 people for over 15 years and found that daily consumption of oranges was associated with a 60% lower risk of developing the disease 15 years later. While oranges may not have ‘magic powers’, it seems some of their components do have powerfully protective properties.

"The data shows that it is the flavonoids found in oranges which are responsible for this protective effect", said study author Professor Bamini Gopinath. "Flavonoids are powerful antioxidants found in many fruits and vegetables. They offer anti-inflammatory benefits for the immune system."

In fact these compounds, which help to keep plants healthy and are responsible for the yellow, orange red and purple colours of the various plant parts (1), exert a wide range of biological activity:

A powerful antioxidant action. As a result of one of their highly reactive group, flavonoids are able to inactivate and stabilise oxidising agents (2-6). They thus protect nucleic acids, prevent the harmful mutations responsible for various forms of cancer, and inhibit carcinogenesis, angiogenesis and cell proliferation (7).
An anti-inflammatory effect. Flavonoids also inhibit the principal inflammatory enzymes cyclooxygenase (8) and lipoxygenase (9-11).
Protection for blood vessels. They have a beneficial effect on blood vessels by maintaining optimal vascular permeability (12), and are indeed used for treating chronic venous insufficiency (13).
Anti-ulcer properties. Flavonoids also protect the gastric mucosa from various ulcer-inducing agents (14).
An anti-cataract effect. In addition to helping prevent AMD, flavonoids also offer protection against cataracts by neutralising aldose reductase in the lens.

Discovered over the last 30 years, all these effects have yet to be fully understood and there are likely to be further exciting discoveries to come given the promise shown in the latest findings. For example, several studies have identified an association between ingestion of dietary flavonoids and a significant reduction in cardiovascular disease mortality (15-16).

What’s certain is that it’s important to ensure they are from natural sources (such as those contained in FlavoLife and Grapefruit Extract 99 % naringin). Drinks such as red wine, tea and coffee contain substantial amounts of flavonoids, though it’s Citrus drinks, including orange, which are the best for providing flavonoids.

Which other supplements can help prevent AMD?

Age-related macular degeneration affects those over 55 in particular. It leads to vision problems, with sufferers potentially losing the ability to recognise faces ...

Over the last few years, two compounds have been shown to be beneficial for combatting AMD:

Lutein. This is one of three carotenoid pigments present in high concentrations in the eye, specifically in the macula
. Long-term supplementation with lutein has been shown to increase macular pigment density in both healthy subjects (17) and those with AMD (18-19), which slows down the progress of macular degeneration (20-21).
In the two most relevant studies (which lasted over a year), the dose used was 10-20mg/day of Lutein 20 mg (ie, one capsule). Scientists believe lutein acts both by neutralising the oxidising agents which damage the retina (antioxidant effect) and by filtering the blue light which attacks the eye’s photoreceptors.
Oligomeric proanthocyanidins (OPC). Several clinical trials suggest that oligomeric proanthocyanidins from red grape seeds or maritime pine bark (used to produce the excellent supplement Eye Pressure Control) are effective at protecting the eyes from the oxidation and glare that contribute to AMD (22). And OPC just happen to be ... flavonoids.

The study at the centre of this article:
Bamini Gopinath Gerald Liew Annette Kifley Victoria M Flood Nichole Joachim Joshua R Lewis Jonathan M Hodgson Paul Mitchell. Dietary flavonoids and the prevalence and 15-y incidence of age-related macular degeneration. American Journal of Clinical Nutrition, 2018 DOI: 10.1093/ajcn/nqy114

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