There has been a lot of interest in the role of nutrition and nutritional supplements, such as vitamin tablets, and their effect on vision. The main focus has been on how vitamins and minerals might affect age-related eye conditions such as age-related macular-degeneration (AMD) and cataracts. This page explores these issues and looks at the importance of good nutrition and how the eye can be affected by it.
The importance of good nutrition
Good nutrition is very important for both your general and eye health. Good nutrition helps our body to grow, repair wear and tear, protect against infection and to function properly. An eye condition called ‘xerophthalmia’, which is a common cause of childhood blindness in developing countries, is a good example of how nutrition and eye health go hand in hand. This condition is caused by a lack of vitamin A in a person’s diet and could be prevented by eating fresh vegetables, fat (animal and plant) and protein (eg meat, eggs, cheese, fish, poultry, milk, yoghurt, dairy products, nuts, seeds, pulses and grains).
What might cause age-related eye disease?
There are many causes for the various different eye conditions.
Sometimes an eye condition can be related to another medical condition, and some are inherited. Much research is being carried out in various areas of eye health. Often there is no known cause for the development of an eye condition - these conditions are often known as ‘idiopathic’.
A few possible risk factors of eye disease are:
AgeAlthough it may sound obvious, age is the biggest risk factor in age-related eye disease. As we get older the changes in our body processes also affect our eyes.
Oxygen is essential for the human body, but it can also be harmful. Oxygen can produce “free-radicals” which damage cells or prevent them from regenerating as they used to. This cell regeneration process is affected as we get older due to free radicals and other factors.
Our bodies do have a natural protection against the effect of free radicals but under certain conditions this protection is not good enough.
Free radicals damage the retina, a light sensitive layer at the back of the eye. They also affect the lens, a clear tissue found behind the coloured part of the eye known as the iris. The lens helps to focus light onto the retina which then sends an image of what we are looking at to our brain. This is how we see. Mostly, these free radicals are neutralised by the body’s defences. Most vitamins and minerals can help the body and our eyes to combat the effects of free radicals. These vitamins and micronutrients are known as antioxidants and their role in maintaining eye health will be explored in this leaflet.
SmokingSmoking causes harm to the tissues of the eye. Research has confirmed the direct, harmful effects of smoking on eyesight, particularly in the development of cataracts and age-related macular degeneration (AMD). We also know that smoking can make diabetes-related sight problems worse. Cigarette smoking increases free radicals which accelerate ageing and alters the body’s ability to absorb or extract necessary vitamins and minerals from food. Smoking reduces appetite which may result in a poor diet. Poor nutrition also has an adverse effect on eye health. Passive smoking, that is not smoking yourself but breathing in other people’s smoke, is almost as harmful as smoking yourself.
While cataracts are treatable and therefore do not lead to blindness, they remain a major cause of sight loss in the UK. Treatment options for AMD are limited and smokers do not only double their risk of developing AMD, they also tend to develop it earlier than non-smokers.
It has been shown that stopping smoking can reduce the risk of macular degeneration developing. Your GP can tell you about NHS stop smoking services in your area.
DietA balanced diet, with plenty of fresh fruits and vegetables is good for your eye health. Eating a diet low in saturated fats but rich in omega 3 fats and micronutrients derived from green leafy vegetables, fruit, fish and nuts may help prevent and slow down the progression of AMD and age-related cataracts.
ObesityObesity is increasingly being discussed as a risk factor for sight loss. Recent research suggests that obesity may put someone more at risk of developing an eye condition which can cause sight loss, including AMD, cataracts and retinal vein occlusion. In addition, obesity significantly increases the risk of developing diabetes and with it, diabetic retinopathy. Further research is now needed to gain better understanding of the links between obesity and these eye conditions.
SunlightIt has been suggested that eyes can be damaged by continuous exposure to intense sunlight. Many studies show that prolonged periods of sunlight exposure are a risk factor for the development of AMD. The sun’s rays have been linked to the development of cataracts.
For this reason it is very important to reduce exposure of the eye to sunlight. Sunglasses that offer good protection from all angles, are recommended. These not only protect the eye from direct sunlight but also from scattered or reflected light that can enter the eye from above, the sides or below. Wearing a hat with a good brim can decrease eye exposure to light by 30-50 per cent. Sunglasses and hats are, therefore, also recommended for children.
GenderThere is a higher rate of AMD and cataracts among women, possibly because they tend to live longer than men. There also seems to be a hormonal influence and it is reported that Hormone Replacement Therapy (HRT) can reduce these risks.
Nutrition for the eye
Vitamins and the eyeIn various studies and clinical trials antioxidant vitamins found in certain foods have been linked with eye health. They help to maintain healthy cells and tissues in the eye.
The main focus has been on the anti-oxidant vitamins A, C and E. These vitamins can be found in many different sources of fruit and vegetables such as oranges, kiwis, grapefruit, dried apricots, tomatoes, peppers, raw carrots, green leafy vegetables including kale and spinach, green peas, green beans and brussel sprouts. They can also be found in nuts, seeds, dairy products and eggs. These are only a few of the food types in which antioxidant vitamins can be found. The British Nutrition Foundation can provide you with further information on this. Their contact details are at the end of this leaflet.
Lutein and eye healthMore recently it has been suggested that two types of antioxidants, known as ‘carotenoids’, called Lutein (pronounced Loo-teen) and Zeaxanthin (pronounced Zay-a-za-thin) may also help with eye health. Some studies have found that people who have a good diet rich in carotenoids, particularly lutein and zeaxanthin, have a lower risk of developing AMD. Lutein and Zeaxanthin can be found naturally in vegetables and fruit. For example, Lutein can be found in yellow peppers, mango, bilberries, and green leafy vegetables such as kale, spinach, chard and broccoli. Zeaxanthin can be found in orange sweet peppers, broccoli, corn, lettuce (not iceberg), spinach, tangerines, oranges and eggs. Many of these overlap with food types in which vitamins A, E and C are present.
Vitamins supplements and dietA large research trial, called the ‘Age-Related Eye Disease Study’ (AREDS), showed that high quantities of the antioxidant vitamins A, C, E, beta-carotene and the minerals zinc as zinc oxide, and copper as cupric oxide, can help to slow down the progression of AMD. It would be very hard to obtain the large quantity of vitamins used in the trial from your diet. Therefore some people who have AMD may consider supplementation with vitamins and anti-oxidants. Such high dosages of vitamins and minerals might have possible side effects on the body.
Age-related macular degeneration (AMD)
For this reason it is very important to consult your doctor first before taking a supplement.
Eye healthFollowing the AREDS research trial there have been over 150 smaller scale studies looking at how vitamins and minerals, both from food and in a vitamin supplement, can help eye health in general, and in particular AMD and cataracts. A number of these studies have looked specifically at the carotenoids Lutein and Zeaxanthin which have been particularly associated with healthy eyes.
Some of these studies have shown how certain vitamin and mineral supplements can have a positive effect on eyes and sight. Others have shown there to be no or little benefit. For this reason various organisations are calling for further, larger scale research.
As a result of these studies there are now a number of different supplements for eye health on the market. There is still divided medical opinion on the use of supplements for both eye health and for preventing, or slowing down, the progression of AMD and cataracts in particular.
The general consensus of opinion is that with a good balanced diet that includes sufficient fresh fruits and vegetables there should be no need to use supplements.
However, research has shown that many people in the UK do not get enough vitamins and minerals from their diet. Some people might consider taking a supplement for their general and eye health when :
- their diet does not include enough fresh fruit and vegetable
- diet does not include enough vitamins and minerals
- vitamins and minerals from food are not adequately absorbed by the body
- it is hard to obtain or prepare fresh fruit and vegetables
- they have been told to take a supplement by their doctor or nutritionist.
However, experts agree that taking supplements is not a substitute for a healthy diet
Evidence regarding the benefits of nutritional supplements against eye disease is conflicting and there is no real agreement among researchers on this subject at present. However, a consensus has been reached on the importance of a healthy, balanced diet full of fresh fruits and vegetables, particularly leafy green vegetables such as kale and spinach.
Key points to remember:
- Eat a good, balanced diet with lots of fresh fruit and vegetables.
- Discuss changing your diet or taking vitamin supplements with your GP.
- Discuss your diet or taking a vitamin supplement with your GP if you believe that your diet may be inadequate.
- The biggest avoidable risk is smoking.
- Protect your eyes from sunlight. Use good quality sunglasses, ie those that have the ‘CE’ mark, which means they meet the European Union Quality Standards. Wearing a brimmed hat also offers very good protection.
- Get your eyes tested at least every two years and more frequently if necessary.
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