People often turn to supplements or superfoods to ward off macular disease or prevent its progression, but new Australian nutritional guidelines suggest the concept of ‘food synergy’ might be more effective. So what is the ideal macular disease diet?
Eye healthcare professionals often advise their patients on diet. In fact, a survey of Australian optometrists found two-thirds of practitioners regularly discuss the impact of diet on eye diseases, and 91% routinely recommend nutritional supplements to age-related macular degeneration (AMD) patients. Given the emphasis on positive eating habits, it’s perhaps surprising there are currently no official nutrition guidelines for AMD.
But there is a clear need for evidence-based dietary information, according to Macular Disease Foundation Australia (MDFA), which has worked with homegrown academics to provide key insights into the type of eating patterns that reduce the likelihood – and even protect against – AMD.
In May 2024, as part of its Macula Month awareness campaign, MDFA is launching updated Nutrition Guidelines for AMD. The organisation recently conducted a systematic review evaluating the strength of the evidence for dietary patterns, foods, nutrients and supplements to prevent AMD and/or slow its progression.
According to MDFA, randomised controlled trials (RCTs) have reported the efficacy of multi-antioxidant supplements in reducing the risk of late AMD. An association between certain antioxidant-rich foods and fish in lowering the risk of AMD was first noted in epidemiological research in the 1990s. Meanwhile, the high intakes of vegetables, fruit, fish and plant-based proteins in traditional Mediterranean and Asian-style diets have also been associated with lower incidence of AMD.
MDFA’s updated nutrition recommendations are based on the first systematic review of all published systematic reviews investigating dietary patterns, food, nutrients, nutrition supplements and AMD, performed in association with the University of Sydney. The organisation’s CEO Dr Kathy Chapman holds a PhD in public health nutrition and began her career as a dietitian.
To develop the guidelines, systematic reviews were included if they investigated an association between any diet, food, macronutrients, micronutrients and/or dietary supplements and AMD (early, intermediate, late, atrophic and/or neovascular) in adults.
Interpreting the large number of published studies linking different eating patterns and food groups is a big undertaking and required MDFA to analyse both observational study designs and RCTs. Observational studies – like cohort studies – follow up large numbers of people in the population over time and help to inform associations with eating patterns and individual foods. RCTs also help to understand if nutrition supplements taken in capsule form are effective. From 575 studies identified in the literature search, 21 systematic literature reviews were identified for analysis.
Chapman says healthy eating can help prevent age-related macular degeneration (AMD) by providing a wide range of potentially protective antioxidants like omega-3 fatty acids, lutein, zeaxanthin, vitamins C and E, and zinc.
“Eating patterns that boost consumption of these nutrients protect against oxidative stress, inflammation, and cellular damage in the eyes, reducing the risk of developing AMD or slowing its progression. It’s important that a healthy, macula-friendly diet be an integral part of both prevention and treatment for AMD,” she says.
“A key finding we found in our study is that it is important to consider overall eating patterns rather than focussing on single nutrients and foods. People often try to improve their diets with nutrient supplements or so-called ‘super-foods’, but more and more studies are pointing to the benefits of an overall healthy eating pattern with a wide variety of plant-based foods.”
‘Food synergy’, the combined action of food constituents on overall health, is an important message MDFA wants practitioners and the broader macular disease community to take note of.
Studying foods consumed regularly together may demonstrate an enhanced effect on health, compared to studying foods or nutrients in isolation. MDFA says this might explain why Mediterranean and Asian-style eating patterns were consistently linked to a lower risk of developing – and slowing progression of – AMD while the evidence was less certain for a high intake of individual foods and nutrients.
Mediterranean and Asian-style diets both include a high intake of fresh fruit and vegetables, fish, nuts, and seeds, with little meat and dairy. While Asian-style diets have a high intake of rice, soy products and other plant-based foods, the Mediterranean diet is based on regular use of olive oil and cereal products. Both feature a high intake of fish, foods rich in omega-3 fatty acids, and antioxidants – foods with the strongest protective associations.
In MDFA’s study, omega-3 polyunsaturated fatty acids and fish consumption were frequently reported to protect against AMD.
Foods rich in lutein and zeaxanthin, like dark green leafy vegetables (such as kale and spinach), broccoli, peas, corn and eggs, are likely associated with reduced risk of developing or progressing to late AMD. Multi-antioxidant supplements were associated with delaying progression of AMD, but not preventing it.
According to MDFA, new evidence shows that more than one standard alcoholic drink was likely associated with higher risk of developing early AMD. High meat consumption – especially red and processed meat – was also associated with a probable increased risk of developing early AMD.
MDFA says its findings indicate that following a Mediterranean diet may protect against both early and late AMD, while adherence to an Asian-style diet may delay the progression of late AMD. The research has shown inflammation plays a role in the development of chronic conditions like AMD. A Mediterranean diet has been linked to lower levels of oxidative stress biomarkers. This may be due to the antioxidant and anti-inflammatory properties of fruit, vegetables, and fish.
“As part of our Macula Month awareness program, we urge all eye health professional to encourage their patients to follow eye-healthy diets,” Chapman says.
“Nutritional information is crucial for holistic patient care as it impacts physical health, mental well-being, and overall quality-of-life. Understanding dietary needs helps manage chronic conditions, like AMD, and supports recovery from illnesses, enhances energy levels, promotes mental clarity, and contributes to emotional wellbeing, leading to comprehensive and effective healthcare outcomes.”
NOTE: For a copy of MDFA’s updated Nutrition Guidelines for AMD, visit here.
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