Nutrition and the eye

Introduction

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.

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).

There are many books on nutrition and eating a balanced diet. This topic will only be looked at briefly here. For further information on nutrition and healthy eating contact the British Nutrition Foundation (BNF).

Nutrition for the eye

Vitamins and the eye.

In 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
•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.

Lutein and eye health.

More 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 diet

Age-related macular degeneration (AMD)

A 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.

For this reason it is very important to consult your doctor first before taking a supplement.

Eye health

Following 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 vegetables
•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.

Conclusion

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.