People often turn to supplements or superfoods to ward off macular disease or prevent its progression, but new Australian dietary guidelines suggest the concept of ‘food synergy’ could be more effective. So what is the ideal diet for macular disease?
EMany healthcare professionals often advise their patients about diet. In fact, a survey of Australian optometrists found that two-thirds of doctors regularly discuss the impact of diet on eye disease, and 91% routinely recommend nutritional supplements to age-related macular degeneration (AMD) patients. Given the emphasis on positive eating habits, it may be surprising that there are currently no official dietary guidelines for AMD.
But there is a clear need for evidence-based nutritional information, according to Macular Disease Foundation Australia (MDFA), which has worked with home-grown academics to provide key insights into the types of diets that reduce the risk of AMD and even protect against it. .
In May 2024, as part of the Macula Month awareness campaign, MDFA will launch updated nutritional guidelines for AMD. The organization recently conducted a systematic review evaluating the strength of the evidence for diets, foods, nutrients and supplements to prevent AMD and/or slow its progression.
According to MDFA, randomized controlled trials (RCTs) have reported the efficacy of multi-antioxidant supplements in reducing the risk of late AMD. A link 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 intake of vegetables, fruits, fish and plant proteins in traditional Mediterranean and Asian diets has also been associated with a lower incidence of AMD.
MDFA’s updated dietary recommendations are based on the first systematic review of all published systematic reviews examining dietary patterns, diet, nutrients, dietary supplements and AMD, conducted in collaboration with the University of Sydney. The organization’s CEO, Dr. Kathy Chapman, has a doctorate in public health nutrition and began her career as a dietitian.
To develop the guidelines, systematic reviews were included if they examined an association between diet, nutrition, macronutrients, micronutrients, and/or nutritional 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 major undertaking and required MDFA to analyze both observational study designs and RCTs. Observational studies – such as cohort studies – follow large numbers of people in the population over time and help substantiate associations with dietary patterns and individual foods. RCTs also help to understand whether dietary supplements in capsule form are effective. From the 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, such as omega-3 fatty acids, lutein, zeaxanthin, vitamins C and E, and zinc.
“Eating patterns that encourage 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 is important that a healthy, macula-friendly diet is an integral part of both the prevention and treatment of AMD,” she says.
“A key finding we found in our research is that it is important to consider overall eating patterns rather than focusing on individual nutrients and foods. People often try to improve their diets with nutritional supplements or so-called ‘superfoods’, but more and more research points to the benefits of an overall healthy diet with a wide variety of plant-based foods.”
“Food synergy,” the combined action of food components on overall health, is an important message that MDFA wants practitioners and the broader macular disease community to take note of.
Studying foods that are regularly consumed together can demonstrate an improved effect on health, compared to studying foods or nutrients separately. MDFA says this could explain why Mediterranean and Asian diets were consistently linked to a lower risk of developing – and slowing the progression of – AMD, while the evidence for high intakes of individual foods and nutrients was less certain.
Mediterranean and Asian-style diets both include high intakes of fresh fruits and vegetables, fish, nuts and seeds, with little meat and dairy products. While Asian-style diets include a high intake of rice, soy products and other plant foods, the Mediterranean diet is based on regular consumption of olive oil and grain products. Both include high intakes of fish, foods rich in omega-3 fatty acids and antioxidants – foods with the strongest protective associations.
In MDFA’s research, it was often reported that omega-3 polyunsaturated fatty acids and fish consumption protect against AMD.
Foods rich in lutein and zeaxanthin, such as dark green leafy vegetables (such as kale and spinach), broccoli, peas, corn, and eggs, are likely associated with a reduced risk of developing or developing late-onset AMD. Multi-antioxidant supplements were associated with slowing the progression of AMD, but not preventing it.
According to MDFA, new evidence shows that more than one standard alcoholic drink was likely associated with a higher risk of developing early AMD. High meat consumption – especially red and processed meat – was also associated with a likely 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 following an Asian diet may slow the progression of late AMD. The research found that inflammation plays a role in the development of chronic conditions such as 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 fruits, vegetables and fish.
“As part of our Macula Month awareness program, we urge all eye care professionals to encourage their patients to follow eye-healthy diets,” says Chapman.
“Nutritional information is crucial to holistic patient care because it impacts physical health, mental well-being and overall quality of life. Understanding nutritional needs helps manage chronic conditions, such as AMD, and supports recovery from disease, improves energy levels, promotes mental clarity and contributes to emotional well-being, leading to comprehensive and effective healthcare outcomes.”
NOTE: Visit here for a copy of MDFA’s updated Dietary Guidelines for AMD.
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