Age related macular degeneration (AMD) affects around 20% of people aged over 65. It is the commonest cause of registered blindness in people over the age of 50 years yet is largely a preventable disease. Diet plays an important role in both preventing and treatment macular degeneration, and it’s never too late to make dietary improvements to help protect your vision.
What is AMD?
Age related macular degeneration (AMD) is a painless deterioration of the macula – a part of the retina involved in fine vision such as reading and recognising faces. Macular degeneration causes a widening circle of visual distortion in the centre of your visual field. Initially you may notice that straight lines look wavy, but as it progresses, it typically obliterates words when you try to read and blanks out someone’s face when you look straight at them. There are two forms of macular degeneration – wet and dry.
Wet AMD is the least common form (15% of cases) and is diagnosed when new blood vessels grow into the back of the eye. These vessels are fragile and start to leak fluid into surrounding tissues. Wet AMD can be treated by sealing the leaking blood vessels or by injecting drugs (eg ranibizumab, bevacizumab) into the eye which block their growth.
Dry AMD is the most common form (85% of cases) and is diagnosed when no new blood vessels are seen. The mainstay of treatment for ‘dry’ AMD is dietary advice, and supplements that include lutein, zeaxanthin, antioxidants (zinc, vitamins C, E) and omega-3 fish oils may be prescribed by an ophthalmologist to help slow the progression of dry AMD.
What causes AMD?
The exact cause of age realted macular degeneration is uncertain, but a number of factors are known to increase the risk, including:
- Increasing age
- Family history
- Smoking tobacco
- Having poorly controlled high blood pressure
- Having a raised cholesterol level
- Excessive exposure to strong sunlight
- Lack of the carotenoids (lutein and zeaxanthin) in the diet.
AMD and carotenoid pigments
The macula of the eye contains three carotenoid pigments, lutein, zeaxanthin and meso-zeaxanthin. These bright yellow pigments filter out harmful blue light so it doesn’t reach the delicate visual receptors within the macula, and are sometimes referred to as Nature’s Sunglasses. As antioxidants, these pigments also neutralise damaging chemicals produced during the normal processes of light detection.
When levels of macular pigments are reduced, cell damage dramatically increases, and the delicate macula starts to fail. People with macular degeneration have, on average, 70% less lutein and zeaxanthin in their eyes than those with healthy vision.
You can’t make lutein, and must therefore obtain it from your diet yet, perhaps surprisingly it is not yet classified as an essential nutrient. When intakes of lutein are adequate, you can make small amounts of the other two pigments from it.
Levels of carotenoid pigments found in the eye reflect those present in the brain and, as a bonus, increasing your intake of lutein may protect against Alzheimer’s disease and other forms of dementia, too!
Food sources of carotenoids
Lutein and zeaxanthin are found in kale, spinach and other dark green leaves, and in sweetcorn, carrots, mangoes, apricots – any yellow-orange fruit and veg, in fact. Lutein is also responsible for the bright yellow orange colour of egg yolks.
People with good dietary intakes of lutein are up to 40% less likely to develop age-related macular degeneration than those with low intakes. In one study, people with the highest lutein and zeaxanthin levels in the retina had an 82% lower risk of AMD than those with the lowest levels.
|Lutein per typical serving
|Green peas (tinned)
|Green beans (cooked)
|Eggs (2 large)
|Orange (1 medium)
Lutein supplements and AMD
Taking lutein supplements can significantly increase blood levels of lutein, and the amount of macular pigment present in the retina. In an early pilot study, two people took 30 mg lutein supplements per day, and their macular density increased by 21% and 39% after 20 weeks. Even after lutein was discontinued, their maculae continued to improve for about six weeks.
Lutein supplements also increase macular pigment levels in people with early AMD, with macular pigment optical density increasing from 0.24 to 0.31 after 18 to 20 weeks supplementation. This 39% increase shows that a diseased macula can still accumulate and stabilise lutein and zeaxanthin.
The LAST study (Lutein Antioxidant Supplementation Trial) involving 90 Veterans with age related macular degeneration showed that macular pigment optical density increased over time in those taking 10mg lutein supplements daily for one year, but declined in those not taking lutein supplements. Visual acuity also improved in those with ‘dry’ AMD by the equivalent of 5.4 letters on a Snellen chart with improved contrast sensitivity. No improvement occurred in those taking inactive placebo.
A follow-up study, LAST2, found that people with age related macular degeneration who had the lowest density of macular pigment, and who were in greatest need of supplements, were most likely to benefit from taking either a 10mg lutein supplement or a lutein plus antioxidant supplement. For those responding, macular pigment optical density continued to increase for at least 12 months, with the benefits still continuing when the trial ended.
Omega 3 fish oil and AMD
Fish oil contains long-chain omega-3 fatty acids, DHS and EPA, which help to keep cell membranes fluid to allow the optimal flow of information from nerve cells within the retina to visual processing areas within the brain. The results from 8 studies, involving 128,988 people, show that in those who regularly eat fish, the risk of developing early AMD is reduced by 17%, and the risk of developing late AMD is reduced by 24%.
The most protective types of fish are the oily fish, such as salmon, herring, mackerel, sardines and fresh (not tinned) tuna.
Vitamin supplements and AMD
Vitamin and mineral supplements are prescribed to prevent and treat age-related macular degeneration following successful clinical trials.
The first Age-Related Eye Disease Study (AREDS) found that people with intermediate or advanced AMD in one eye, who took the AREDS supplement reduced the chance of their AMD progressing or developing in the other eye by around 25% compared with placebo.
The original AREDS trial supplied varying combinations of:
- 500 milligrams of vitamin C
- 400 international units (IU) of vitamin E
- 15 milligrams of beta-carotene
- 80 milligrams of zinc as zinc oxide (an unusually high dose)
- 2 milligrams of copper as cupric oxide (included to offset the effects of high dose zinc on copper metabolism)
The full AREDS formula (patented by Bausch & Lomb) was shown to reduce the risk of developing advanced age-related macular degeneration (AMD) by about 25%, and reduced the risk of vision loss by about 19%.
Although this formula remains the gold standard treatment for AMD, the original formula has been called into question:
- A follow-up trial derived from the Physicians’ Health Study (22,071 U.S. males aged 40 to 84) found that betacarotene had no significant effect on development of AMD, advanced maculopathy or maculopathy with or without vision loss.
- High-dose betacarotene supplements are best avoided by those who smoke, as an association was found between high betacarotene intake and risk of lung cancer in smokers (but a reduced risk in non-smokers).
- Researchers from the London’s Institute of Ophthalmology have found high zinc levels in sub-retinal pigment epithelial deposits and believe that zinc may play a role in the development or progression of AMD.
- 66% of participants took Centrum (containing a RDA amount of Vit C, E, betacarotene and zinc) which may have reduced the difference in vitamin concentrations between the treated and placebo groups.
So, a second study was planned, AREDS2, to look at the effects of adding lutein, zeaxanthin and omega-3 fish oils to the original formulation, and reducing the dose of zinc.
This study compared the original AREDS formula against a modified formula which supplied:
- 10mg lutein and 2mg zeaxanthin
- 350mg DHA, 650mg EPA
- 500 mg vitamin C
- 400 international units (IU) of vitamin E (267mg)
- 25 mg zinc
The addition of lutein and zeaxanthin, DHA+EPA, or both to the AREDS formulation produced a similar effect to the original formula. Because of concerns about the effects of betacarotene possibly increasing the incidence of lung cancer in former smokers, the modified lutein + zeaxanthin formula is the better option.
NB These trials involved people with existing macular degeneration. The benefits of taking lutein supplements are that they offer protection against AMD developing in the first place.
Could you have macular degeneration?
You could have macular degeneration if your sight is deteriorating and you are noticing wavy distortion of straight lines, or if you can’t see things clearly when you look right at them. A simple grid of lines can act as a screening tool for macular degeneration. Known as an Amsler Grid, you simply look at it to see if any lines look wavy or distorted, or if any areas of your visual field are missing.
|Click here to download a free Amsler Chart from the American Macular Degeneration Foundation.
If you are experiencing any visual problems, seek medical advice from an optometrist or your doctor without delay as early diagnosis is vital.
General eye health advice
- Have your eyes tested regularly – at least once a year
- Wear sunglasses that carry the UV400 mark to protect your eyes from the sun.
- If you smoke, do your utmost to stop
- Eat at least five portions of fruit and vegetables per day, including those that are lutein rich
- Consider taking a lutein supplement as a nutritional safety net.