Can leafy greens or the Mediterranean diet support eye health? A well-balanced diet is key for overall health but there are certain nutrients that can protect against age-related macular degeneration (AMD) too. There is a large body of research eye health professionals can learn from that examines how certain diets can decrease the risk of conditions like AMD, which we’ll review in this post.
Two carotenoids, lutein and zeaxanthin, play a vital role in maintaining sight and protecting our eyes. They are antioxidants that protect against cell damage, maintain the macula and guard against oxidative stress. They aren’t produced by the body so we need to access them in our diet, which is where ‘the AMD diet’ comes in… So, which foods provide the best sources of lutein and zeaxanthin to protect the eye?
Vegetables, Fish, Nuts
Studies show that dark, leafy green vegetables (spinach, kale, mustard greens) contain high levels of lutein, an antioxidant that protects and maintains macula. These vegetables have the highest levels of lutein per 100g:
- Kale: 11.4mg
- Red pepper: 8.5mg
- Spinach: 7.9mg
- Lettuce: 4.7mg
- Leek: 3.6mg
- Broccoli: 3.3mg
- Peas: 1.7mg
Research also suggests that lightly cooking these vegetables helps to increase the bioavailability, so the body can absorb more of the nutrients. It is relatively easy to add these vegetables to a daily diet – a small portion with lunch or your main evening meal.
The Mediterranean Diet
This nutrient-rich diet is already well-known to protect against heart disease and type 2 diabetes, but it can also play a role in reducing AMD risk. The diet, made up of olive oil, nuts, fish, vegetables, fruits and whole grains, is thought to be beneficial because it is low in saturated fat and high in omega-3. The Mediterranean diet is also beneficial for health because it is low in processed foods and red meat.
The AREDS study (age-related eye disease study) demonstrated the benefits of the diet for those with AMD. Those who adhered to the Mediterranean diet and consumed fewer processed foods and red meat were associated with reduced risk of progression to advanced AMD.
Two other smaller studies, detailed in our blog post, demonstrated that closely following the Mediterranean diet offered some protection against AMD. The antioxidants present in the diet, especially omega-3, could lower risk of AMD by up to 35%.
The Low GI Diet
The link between AMD and the low GI diet is less clear but does offer us some understanding of how the condition is affected by nutrition. A recent study by Tufts University found that the development of AMD can be slowed by reducing or eliminating starchy carbohydrates.
The low glycaemic diet is designed to avoid rapid spikes in blood glucose levels, by reducing intake of foods like potatoes, white rice, white bread and sugary processed foods. Foods that have a low glycaemic index are broken down more slowly by the body, keeping blood glucose levels stable. Certain fruits and vegetables, whole grains (brown rice, wholemeal bread), pulses and low-fat dairy products have a low glycaemic index.
The study found that mice following a low GI diet developed fewer age-related lesions in the retina, and they were less severe compared with those on a high GI diet. The team then found that the high GI diet resulted in the development of advanced AMD symptoms such as loss of cell functionality.
This study was only undertaken on mice and there have been no human trials yet, so it is early days, but it does help us understand what puts the retina at risk. Read more about the study and the low GI diet in our related blog post.
AREDS 2
This landmark AMD study involved 2500 participants who were monitored over a 13-year period, with diet forming a key part of the research. The AREDS 2 study, and its predecessor, AREDS 1, found that certain nutrients could slow down the progression of AMD by approximately 25%.
Each study used a supplementation formulation which was given to the participants, and the results from it studied. The AREDS 2 formula contained the following:
- Vitamin C – 500mg
- Vitamin E – 400 IU
- Copper – 2mg
- Lutein – 10mg
- Zeaxanthin – 2mg
- Zinc – 25mg
In both studies, the research found that the AREDS formula was effective in those with intermediate AMD, slowing progression by up to 25% and slowing vision loss by 19%. Therefore it may be recommended to those with this level of AMD, and it also suggested that those with a diet lacking in the correct nutrients would benefit.
Lutein and zeaxanthin supplementation
This brings us on to supplementation, which is currently a key part of mitigating AMD risk, used widely in eye care. For those who have been screened and found to have low MPOD levels, it is recommended that they have at least 10mg of lutein and 2mg zeaxanthin per day.
It is, however, difficult to maintain this level of intake from diet, and lutein and zeaxanthin are not produced by the body. A person would need to eat the equivalent of 3 cups of spinach per day or 40 large eggs, whereas they could just take a supplement instead.
Lutein and zeaxanthin levels decline as people age, putting them at greater risk of conditions like AMD, so a supplement is often recommended to ward off the risk of AMD. A daily supplement can be taken by those who have certain risk factors like family history, low MPOD levels or a poor diet.
Diet and AMD – what’s the best approach?
Diet and supplementation play a significant role in maintaining eye health, but monitoring is also very important. Diet and lifestyle are just one risk factor, so it is important that those most at risk of AMD come for regular MPOD screening. Regular checks will help identify the risk of AMD developing, allowing the patient to protect their eyesight and take steps to prevent AMD developing as early as possible.
Eye health professionals should encourage their patients to take responsibility for their health – recommending a balanced diet and an active lifestyle accompanied by regular screening checks. Read more about macular pigment screening in our free whitepaper.