Nutrition and the eye

There is evidence to show that a healthy diet prevents the development of eye conditions, although this link isn't as strong as it is for other conditions such as heart disease

Eating a healthy balanced diet rich in fruit and vegetables may help to keep your eyes as healthy as they can be.

A balanced diet is essential for staying healthy. A diet that is based on starchy foods such as rice, potatoes and pasta, with plenty of fruit and vegetables, foods rich in protein such as meat, fish and pulses (for example lentils), some milk and diary and not too much fat, salt or sugar, will give you all the nutrients you need.

Losing weight or maintaining a healthy weight means eating the right foods in the right amounts and exercising regularly. Being overweight in itself does not seem to be a risk factor for any particular eye condition, but being overweight does put you at risk of a number of health problems, including

  • high blood pressure
  • type 2 diabetes
  • heart disease
  • stroke
  • some cancers.

Some of the health complications of being overweight can cause problems that can affect your sight. These include retinal vessel occlusions, diabetic eye problems and eye conditions related to stroke. You can reduce your risk of developing these conditions, which can lead to sight loss, by maintaining a healthy weight or by losing weight if you need to.

Most people can get all the vitamins and minerals they need from eating a healthy and balanced diet. However, some people may be advised to take a supplement by their GP or eye specialist.

At present it is felt that perhaps people who have a poor dietary intake of vitamins and minerals, for example some elderly people who may have difficulties with digestion, may benefit from taking supplements to help prevent eye conditions such as age-related macular degeneration from developing, although more research is needed to confirm this.

What is a healthy diet?

Carbohydrates: Starchy foods such as bread, pasta and rice should make up around one third of everything you eat. Choosing wholegrain or wholemeal varieties, such as wholemeal (brown) bread, brown rice and wholewheat pasta, as well as eating the skins or jackets of potatoes, increases the amount of fibre (roughage) you eat.

Fruit and vegetables: You should try to eat around five portions of fruit and vegetables a day, as they are a very important source of vitamins and minerals. Your five-a-day can include fresh, frozen, dried and tinned fruit and vegetables. An apple, banana or similar-sized fruit, a slice of melon or three heaped tablespoons of vegetables are all one of your five-a-day portions.

Protein: The protein found in meat, fish, eggs, milk and dairy and in pulses such as beans, nuts and seeds are important for repair and growth of your body. Protein is also a good source of vitamins and minerals, such as iron, zinc and B vitamins.

If you follow a vegetarian or vegan diet it is important to make sure that you eat protein from a wide range of sources. These can include pulses such as beans and lentils, non-dairy sources such as tofu and soya, as well as eggs and low fat dairy. Meat is also one of the main sources of vitamin B12 in our diets. If you eat meat, try to eat lean meat and skinless chicken to reduce the amount of fat in your diet.

Fats: Fats and sugar are both sources of energy for your body, but if you eat too much of these you can put on weight leading to obesity, which increases your risk of type 2 diabetes, heart disease, stroke and some cancers. Eating a diet high in saturated fat can cause the level of LDL, or 'bad' cholesterol, a type of fat, to build up in your blood over time. Raised LDL cholesterol increases your risk of heart disease and this may be the case even if you are not overweight or obese.

Cutting down on foods that are high in saturated fat and instead having smaller amounts of foods that are rich in unsaturated fat is generally a good idea. Saturated fat is found in foods such as cheese, sausages, butter, cakes, biscuits and pies. Unsaturated fats can help to lower your cholesterol. These are found in foods such as oily fish, nuts and seeds, avocados and in vegetable and olive oils.

Added sugar: It also important to cut down on added sugar in your diet. Added sugar is found in items such as cakes, fizzy drinks, chocolate and other sweet foods such as pastries and jam. There can also be hidden sugar added to some pre-prepared savoury foods such as pasta sauces and baked beans. You do not need to cut down on the natural sugars found in foods like fruit and milk.

Nutrition and eye conditions

A balanced diet is important for our overall health and therefore may also be helping to keep our eyes as healthy as they can be. new blood vessels, which leak blood or fluid. When this happens at the macula area, the middle of the retina, these fluids cause the macula to swell. This swelling is known as macular oedema.

Age-related macular degeneration

Age-related macular degeneration (AMD) is a condition which mainly occurs in older people. In AMD, the cells of your macula, the central part of the retina, stop working, causing a deterioration of central vision. This is the sight we use for detailed tasks such as reading and recognising faces.

There are two types of AMD: dry and wet. In the dry type, the cells at your macula slowly stop working correctly and in the wet type, the cells stop working and the eye tries to fix this problem by growing new blood vessels. However, these new vessels are weak and grow incorrectly, causing leakage, damage and scarring at the macula, affecting vision.

Wet AMD is the quicker progressing form of the condition, leading to serious changes to your central vision in a short period of time. There is currently no treatment for dry AMD, but there are treatments available for wet AMD. The nutritional supplements concerned with AMD are the antioxidant vitamins A (which our bodies convert from beta-carotene in our diets), C and E, as well as the trace element zinc and the micronutrients lutein and zeaxanthin. Lutein and zeaxanthin are naturally found as pigments in the macula.

It is thought that antioxidants are helpful in AMD because of the free radical theory of cell damage. This is that over your lifetime, free radicals, highly reactive substances created in your body by breathing, eating and by other factors such as air pollution and smoking tobacco, cause damage to the cells in your body. This is the wear and tear we call ageing.

Two recent large-scale studies done in America called the Age Related Eye Disease Studies (AREDS and AREDS2) explored the role of these antioxidants in slowing down the progression of AMD in people already diagnosed with the condition. AREDS and AREDS2 found that for some people with AMD, taking an antioxidant formula did slow down the progression of their condition.

Cataract

The most common type of cataract occurs as you get older. Cataracts develop because as you age the lens of your eye changes in response to the natural ageing process. This means that your once clear lens becomes cloudy.

Although getting older is the strongest risk factor for developing a cataract, some studies have shown that a healthy diet rich in antioxidant containing foods may decrease the risk of developing cataracts. Other studies seem to show that taking some vitamins and minerals may be protective against developing cataracts.

However, at present evidence is varied and there are currently no clear answers regarding diet and supplements to prevent age-related cataracts. Therefore, it may be the case that a healthy diet rich in antioxidant containing foods such as fruits and vegetables, may also help prevent or slow down cataracts, as well as being beneficial to our general health.

Dry eye

Dry eye is a common condition where there may be a problem with your tears that usually keep your eyes comfortable and moist. Clinical trials have shown that omega 3, a group of fatty acids that we get from our diets, can have a positive effect on the symptoms of dry eye when taken in certain quantities.

Omega-3 can be obtained from our diet by eating oily fish such as anchovies, herring, mackerel, salmon, sardines, trout, herring and fresh tuna. The NHS recommends that we eat at least two portions of fish a week, including one of oily fish. If you do not eat fish you can also get omega-3 by eating flaxseed/linseed or rapeseed oils and soya foods such as tofu, as well as walnuts and eggs enriched with added omega-3.

Taking omega-3 supplements have also been found to help with the symptoms of dry eye in some trials. However, as with all supplements these may not be suitable for everyone and if you are thinking of taking omega-3 supplements for dry eye it would be important to discuss this with your GP or ophthalmologist (eye specialist) before starting.

Conclusion

Eating a healthy diet and controlling your weight helps to maintain your general health, preventing conditions such as high blood pressure, type 2 diabetes, heart disease, stroke and some cancers.

For people with AMD it has been shown that certain supplements can, for some, help to slow down the progression of this condition. Importantly, evidence suggests that having a diet rich in fruit and vegetables may help to keep your eyes as healthy as they can be. If you have any concerns about your diet you may want to discuss these with your GP who should be able to give you more advice about healthy eating.