Eating plenty of fruit and vegetables could lessen the risk of an eye disease now affecting more than 200,000 Kiwis.

Age-related macular degeneration, or AMD, is an increasingly common problem among people older than 50 and leads to the loss of central vision.

In her eight years working as an optometrist, Naoko Chapman was often asked by patients whether there was anything else they could do to help their vision.

"I felt very uncertain about how to best advise these people on nutrition."

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She returned to the University of Auckland and teamed up with optometrist Associate Professor Rob Jacobs and registered dietician Dr Andrea Braakhuis to investigate any links to diet.

Previous research had focused on dietary supplements that contained beta-carotene, vitamin C, vitamin E and copper, as well as zinc.

The supplements were found to lower the progression of eye disease from early to advanced stages of AMD by a quarter, but zinc appeared to have no added benefit.

"While I found this to be interesting, the downside to supplement studies are they fail to include the complex nutrient make up of food and diet patterns representing the way we eat every day," Chapman said.

"It's not just the supplement studies that have a singular focus - most studies investigated a few nutrients or foods, making it difficult to get an overview of the effect of total diet on vision."

Chapman and her colleagues trawled through more than 1,300 published papers, before analysing 18 high-quality studies.

The evidence from the research found that sticking to a Mediterranean diet was linked with a decreased risk of AMD progression.

An Oriental diet pattern - with higher intake of vegetables, legumes, fruit, whole grains, tomatoes and seafood - had a lower association with AMD prevalence.

Specifically, eating plenty of vegetables rich in carotenoids and fish containing omega-3 fatty acids could help those at risk.

A Western diet pattern - with higher intake of red meat, processed meat, high-fat dairy products, fried potatoes, refined grains and egg - had a higher association with AMD, as did having more than two alcoholic drinks a day.

The team further found an increased link between AMD and diets containing food high on the glycaemic index, such as sugar, white and some wholemeal breads, and white rice.

"Improving the quality of the diet, increasing the intake of foods that contain the nutrients required by the retina and avoiding foods that cause cell damage will play an important role in protecting against AMD," Chapman said.

"I also believe there is a need for all healthcare professionals to have a better understanding of nutrition so that nutritional advice can be an important aspect of the prevention and management of eye-disease."

Chapman said a gap in the literature made it hard to assess the effect of diet on the early stages of AMD.

"So until there are such long-term studies, we should think about eating well and not rely on quick diet fixes."

While her study had yielded no such easy fixes, the take-home message was nonetheless simple.

"Let's eat more vegetables and fruit and make a long-term plan of eating foods that are good for the body; including your eyes."