Can omega-3 beat blindness?

29 June 2007

Omega-3 could help keep eyes healthy, say scientists. A tiny boost in this essential nutrient halves eye damage in mice, potentially saving their sight. Antenna takes a closer look...

This research was published in the journal Nature Medicine on 24 June 2007.

Blood vessels developing in a mouse retina.

Image: Chris Aderman

The growth of abnormal blood vessels in the eye, shown here in a mouse retina, can eventually lead to the retina becoming detached, causing blindness.

Image: Kip Connor

Around 2 million people in the UK have a sight problem and over 370,000 are registered as blind or partially sighted. The most common cause of sight loss is damage caused by the abnormal growth of blood vessels in the retina, the layer of light-sensitive cells at the back of the eye.

Our bodies don't make omega-3 fatty acids, but oily fish such as salmon and mackerel are packed with omega-3, and nutrition experts recommend we eat at least one portion a week.

Image: iStockphoto.com/Maria Bacarella

Now scientists have found that omega-3 could protect the retina from damage. It's another plus point for this essential nutrient - scientists have already shown it reduces the risk of heart disease and could even boost brainpower.
Experts from Harvard Medical School in the US tested whether feeding mice more omega-3 fatty acids could help control the growth of abnormal blood vessels in their eyes.
'The retina has one of the highest concentrations of omega-3 fatty acids in the body,' explains eye expert Kip Connor. 'We found that just a 2% increase in the amount of omega-3 in the diet could reduce damage to the retina by up to 50%.'

Kip Connor, Harvard Medical School, Children's Hospital Boston.

Image: Kip Connor

The scientists mimicked how abnormal blood vessels grow in the human eye by exposing mice to high levels of oxygen at a young age. Too much oxygen is toxic to the retina, and when the body tries to repair the damage, abnormal blood vessels form.
The extra omega-3 that the scientists fed their mice reduced inflammation after oxygen damage, helping healthy new blood vessels grow instead of abnormal ones. And they're optimistic the same should hold true for humans. 'Mice are not people, but we're hopeful the findings will carry through,' says Kip.

Western diets are usually lacking in omega-3. A 2% increase would be equivalent to an extra gram a day.

The research holds particular promise for premature babies, who have a high risk of sight loss. The level of oxygen in the womb is lower than in the outside world, and if a baby is born too soon, the sudden increase in oxygen can damage the retinas.
'Very premature babies are likely to be deficient in omega-3,' explains Lois Smith, from Harvard Medical School. 'We're planning a study to see if adding omega-3 to the nutrition that premature babies receive can help prevent damage to their retinas.'

Premature babies born before they are 27 weeks old miss out on a big transfer of omega-3 fatty acids from their mother.

Image: iStockphoto.com/Alison Hausmann

'There's been some evidence that omega-3 can help protect against retina damage associated with old age,' explains sight-loss expert Barbara McLaughlan from the Royal National Institute of Blind People. 'What's exciting is that it seems to have the same effect in other types of retina damage.
'It's always important to emphasise the need for a healthy balanced diet to protect against eye disease, and that includes fish such as salmon, which contains omega-3 fatty acids.'

Barbara McLaughlan, Royal National Institute of Blind People.

Image: Royal National Institute of Blind People

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