Can diet help to beat AMD – the UK’s leading cause of blindness?

What is Age-related Macular Degeneration?

Age-related macular degeneration (AMD) is a progressive blinding disease that damages the macula - the part of the eye that is responsible for our central, detailed and much of our colour vision. It affects 1 in 3 people over the age of 75 years with ~70,000 new cases reported each year.

Although age is the principal risk factor for AMD, it is a complex disease in which genetics and lifestyle also play a part. The fact that the underlying mechanisms of AMD are still not fully understood is a fundamental barrier to developing more effective treatments.

Under the supervision of Dr Arjuna Ratnayaka, PhD student Anna Muir is exploring the relationship between AMD and diet, in the hope that new insights arising from her research will help to beat the UK’s leading cause of blindness. We asked Anna to tell us more about her project and its potential impact.

What’s the background to your project?

"Large-scale research studies involving thousands of participants have shown that an unhealthy diet – by which we mean one that’s high in processed foods, red meat, and fat - can increase your risk of developing AMD by up to 60%. We also know that eating dark green leafy vegetables and yellow-pigmented fruits can help to slow the progression of diseases like AMD and diabetic retinopathy.

What we don’t know currently is what is happening at the cellular and molecular levels within the eye to cause both these harmful and positive effects. That’s what my research aims to address."

What will your project involve?

"In a previous study, the team here at Southampton found that when mice were fed a high fat diet, the structure of their retinas changed and showed signs of developing disease. My experiments will build on this evidence by seeing if retinal disease can be rescued by first feeding the mice a high fat diet, and then a normal diet again. I’ll examine their eyes at specific time points to get a good idea of exactly what is happening in their retinas in response to their diet, and when it is happening.

I’ll also be looking at what happens to human retinal cells when they are treated with oxidised cholesterol. This is a fatty substance, which has been found at significantly higher levels in the retinas of people with AMD than in the retinas of people with healthy eyes."

What is personalised medicine and how could this research help?

"Personalised medicine is about tailoring treatment to the patient. A one-size-fits-all approach doesn’t fit every person’s individual genetics, biochemistry, or lifestyle. So, for example, while certain vitamin and mineral supplements have been shown to slow the progress of AMD, they do not work for everyone –and this could be explained by differences in people’s genetic makeup.

For instance, people with high levels of oxidative stress are more susceptible to AMD. Having high levels of oxidative stress may be due to genetic and lifestyle risk factors. Such individuals in particular may benefit from dietary interventions."

What are some easy changes people can make to look after their eye health?

"Some easy changes are 1) stop smoking, 2) adopt a more healthy, balanced diet. An example of a diet that’s been shown to reduce the odds of developing AMD is the “Mediterranean style” diet. This is made up of a high intake of fruits and vegetables combined with healthy fats like olive oil, and lean meats and fish. This diet is also low in highly processed foods."

What might the long term impact of your research be?

"Recent research suggests that just 53% of ophthalmologists advise those at risk of AMD of dietary changes that they could make. We hope that through our research, we can raise awareness of the importance of diet and how it can protect your vision."