Here’s an overview of common eye conditions, the key nutrients you need to nourish and protect your eyes for good, and a simple diagram that sums it all up beautifully.
A cataract is a clouding of the eye’s natural lens, which lies behind the iris and the pupil. The lens inside the eye is a bit like a camera lens; it focuses light onto the retina to enable clear vision and adjusts the eye’s focus for sharper vision. It is made of water and protein, however as we age, some of the protein may stick together and start to cloud a small area of the lens, making it harder to see; this is a cataract. Over time, the cataract can get bigger and cloud even more of the lens, making it even harder to see. Cataracts are a common cause of vision loss and can significantly alter an individual’s quality of life.
No one knows for certain what causes cataracts, however proposed risk factors include ageing, UV radiation from sunlight and other sources, diabetes, high blood pressure, obesity, prolonged use of steroid medications, smoking, statins, previous eye injury, inflammation or surgery, HRT, high alcohol intake and family history. One theory that’s gaining much attention at the moment is that oxidative stress may have a part to play in the formation of cataracts. Dietary antioxidants such as the carotenoids lutein, zeaxanthin & meso-zeaxanthin, vitamin E, C, zinc and lipoic acid are generally considered to be the best defence against oxidative stress in the eyes.
In a ten-year prospective study examining serum carotenoid levels in 35,551 female subjects, researchers demonstrated that women with the highest intakes of lutein and zeaxanthin had an 18% lower risk of developing cataract compared to those with the lowest intakes. Study results on the impact of antioxidant intake (through diet and supplementation) on cataracts are still varied, however the general trend suggests there is a role for dietary antioxidants for prevention and reducing the progression of cataracts1,2.
Dry eye syndrome
An adequate and consistent layer of tears on the surface of the eye is essential to keep your eyes healthy, comfortable and seeing well. Dry eye syndrome is very common and is a condition caused by a chronic lack of moisture and lubrication on the surface of the eye. Symptoms can include burning and itchy eyes, a feeling that there’s grit in the eyes, aching, heavy, fatigued eyes, blurred vision and sensitivity to light. Consequences can range from subtle but constant eye irritation to scarring of the front surface of the eye. Risk factors include computer use, contact lenses, air conditioning, smoking, ageing, menopause and even some medications such as antidepressants, antihistamines, birth control pills and blood pressure medications. Clinical trials have demonstrated that supplementation with omega 3 and / or omega 6 fatty acids have various benefits for this syndrome including symptom improvement, reduced inflammation of the eye surface and eyelid, increased tear secretion and lengthening the tear break-up time. Together these changes may significantly improve this condition3.
Glaucoma refers to a group of related eye disorders that all cause damage to the optic nerve that carries information from the eye to the brain. Glaucoma usually has few or no initial symptoms. It is often called ‘the silent thief of sight’ because most types typically cause no pain and produce no symptoms until noticeable vision loss occurs. In most cases (but not always), glaucoma is associated with higher-than-normal pressure inside the eye – ocular hypertension. If untreated or uncontrolled, glaucoma first causes peripheral vision loss and eventually can lead to blindness. Some research has found lower levels of macular pigment optical density (MPOD) in some types of glaucoma. The density of macular pigment naturally decreases with age but is significantly supported by dietary intake of antioxidants, in particular carotenoids lutein, zeaxanthin and meso-zeaxanthin. Whilst the research is currently inconclusive, it appears prudent to increase consumption of these crucial nutrients to support prevention or progression of this debilitating condition4.
Age-related macular degeneration (AMD)
Age-related macular degeneration (AMD) is the most common cause of irreversible blindness in people over the age of 50 in the developed world. AMD is a disease of the macula - the small central part of the retina that’s responsible for sharp detailed vision. There are two types of AMD: early and late. Early AMD can be present in the eye without any symptoms, however it often progresses into late AMD and this is when vision changes occur. If left untreated, or deemed untreatable, late AMD can result in loss of central vision, which means you can see everything except what you are directly looking at. Without central vision, someone with late AMD can’t watch TV, read, drive or recognise faces, and this can significantly reduce quality of life. Early diagnosis is important - the earlier a diagnosis can be made, the easier it is to intervene. Smoking (even passive) dramatically increases the risk of AMD and multiple studies have shown that oxidative stress is a major mechanism in the development of AMD. The retina is particularly vulnerable to oxidative stress from sources such as blue light (sunlight, LEDs, phone, tablet, computer screens). It has in built protection in the form of macular pigment – which acts a bit like internal sunscreen for your eyes – blue light filtration is one of the main functions of macular pigment. Macular pigment is composed of carotenoids lutein, zeaxanthin and meso-zeaxanthin. These cannot be made by the body and must be supplied by the diet. Masses of research now show that a high dietary intake of these and other antioxidant nutrients such as vitamins C, E and zinc can both help to prevent and reduce the progression of AMD. Many randomised, placebo-controlled clinical trials have demonstrated that supplementation with carotenoids increases macular pigment levels, improves visual function, and decreases the risk of progression to late AMD5,6.
Diabetic retinopathy is a complication of diabetes, whereby high blood sugar levels cause retinal blood vessels to swell and leak blood, causing damage to the retina. It can cause blindness if left undiagnosed and untreated. Fluctuating blood sugar levels and long-term diabetes increase the risk for diabetic retinopathy. Maintaining even blood sugar levels and controlling blood pressure within a healthy range may help to prevent the condition. The retina is one of the most metabolically active tissues in the body and is highly vulnerable to oxidative stress. Oxidative stress and subsequent effects on cell signalling are considered to be important factors in the development and progression of the condition.
Carotenoids such as lutein, zeaxanthin and meso-zeaxanthin are found in rich supply in the retina and help to protect against oxidative stress. Circulating levels depend largely on dietary intake and lower levels have been reported in diabetes, and have even been linked to the development of diabetes itself.
Evidence supporting the role of carotenoids in the prevention and treatment of diabetic retinopathy is currently limited, but animal models and early human supplementation trials suggest there is a role for lutein and zeaxanthin in reducing oxidative damage and possibly preventing disease progression7.
The nutrients you need to protect your eyes for good
Whilst most people are now aware of the tremendous impact that a great diet can have on many aspects of their health and wellbeing; few people are aware of the dietary changes that can have a significant impact on eye health.
Antioxidants have a significant role to play in maintaining the health of the eye; cellular damage as a result of oxidation is believed to contribute to the development of a wide spectrum of eye diseases. The retina of the eye is particularly vulnerable to damage due to oxidation. Key antioxidant vitamins, such as vitamins E and C, which help to neutralize harmful free radicals may help to protect the eye. Lipoic acid is a particularly useful antioxidant for the eyes as it protects against both fat and water-soluble free radicals and also helps to enhance the effectiveness of other antioxidants.
Carotenoids - Lutein, zeaxanthin & meso-zeaxanthin
Arguably the most important nutrients for eye health – these antioxidant nutrients cannot be made in the body and must be supplied by the diet. Together they form macular pigment, which helps to protect the eyes against the damaging effects of blue light. There is a huge amount of research that demonstrates the significance of these carotenoids to protect against and reduce the progression of common eye conditions such as age–related macular degeneration and to protect the sight of healthy individuals too.
Vitamins E & C
These crucial antioxidant vitamins help to protect the eyes against harmful free radicals. The eyes are particularly vulnerable to damage from oxidative stress and this is believed to contribute to a wide spectrum of common eye problems.
A particularly useful antioxidant nutrient as it protects against both fat and water-soluble free radicals and also helps to enhance the effectiveness of other antioxidants too.
Zinc & copper
The retina is known to have a high concentration of zinc; it interacts with taurine in the photoreceptors of the eye. It is also needed for the functioning of an important enzyme, which converts retinol to retinal, the form of vitamin A used in the eye. Copper binds with zinc, therefore it is advisable to supplement these two minerals together.
L-taurine is the most abundant amino acid in the eyes and may help to prevent or reverse cataracts. It also works closely with zinc to support optimal eye health.
This fruit, similar to blueberries has long been used for the traditional treatment of eye conditions; its active constituents are flavonoid anthocyanosides, which have potent antioxidant activity. Interestingly, World War II British air pilots reported improvements in their night vision following the consumption of bilberries.
Omega 3 & omega 6 fatty acids
Clinical trials have demonstrated that supplementation with omega 3 and / or omega 6 fatty acids have various benefits for protecting the eyes, and particularly for conditions such as dry eye syndrome3. Omega 3 fats are found in rich supply in oily fish such as mackerel, anchovies and herring whilst omega 6 fats are found in starflower (borage) and blackcurrant seed oil. For best effects you can supplement directly with these oils to achieve a higher dose.
The potential for nutrition to impact on eye health is huge…
It’s not the most talked about subject but the potential for nutrition to impact on long-term eye health is absolutely huge. With so many common eye conditions that can lead to blindness and seriously impact on quality of life as we age, it’s never been more important to take action and do what you can to protect your sight.
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1. Christen W. G., Liu S., Glynn R. J., Gaziano J. M., Buring J. E. Dietary carotenoids, vitamins C and E, and risk of cataract in women: a prospective study. Archives of Ophthalmology. 2008;126(1):102–109. doi: 10.1001/archopht.126.1.102. (10 year study)
2. Scripsema NK, Hu DN et al. Lutein, zeaxanthin and meso-zeaxanthin in the clinical management of eye disease. J Ophthalmol 2015; 2015: 865179. Published online 2015 Dec 24. Doi: 10.1155/2015/865179
3. Liu Y, Liang QF. Research update of effectiveness and mechanism of essential fatty acids in treating dry eye. Zhonghua Yan Ke Za Zhi 2017 Mar 11;53(3):225-229. doi: 10.3760/cma.j.issn.0412-4081.2017.03.019
4. Siah WF, Loughman J. Lower macular pigment optical density in foveal-involved glaucoma. Ophthalmology 2015 Oct;122(10):2029-37. doi: 10.1016/j.ophtha.2015.06.028. Epub 2015 Aug 3
5. Bernstein PS, Li B et al. Lutein, zeaxanthin and meso-zeaxanthin: the basic and clinical science underlying carotenoid-based nutritional interventions against ocular disease. Prog Retin Eye Res 2016 Jan: 50: 34 – 66. Published online 2015 Nov 2. Doi: 10.1016/j.preteyeres. 2015.10.003
6. Seddon JM, Ajani UA, Sperduto et al. Dietary carotenoids, vitamins A, C and E, and advanced age-related macular degeneration JAMA 1994; 272: 1413-20
7. Brazionis L, Rowley K, Itsiopoulos C et al. Plasma carotenoids and diabetic retinopathy. Br J Nutr 2009 Jan; 101(2):270-7. Doi: 10.1017/S0007114508006545. Epub 2008 Jun 13