Antioxidants can slow loss of sight in old age, scientists find

Sarah Boseley, health editor
The Guardian, Friday 19 June 2009
Article history
People at risk of going blind in old age may be able to keep their sight for longer by taking antioxidant supplements, scientists have found.

Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly. It affects the macula, the central part of the eye, resulting in increasingly blurred vision. Because the macula is very rich in antioxidants, scientists hypothesised that giving the right nutritional supplements to people at risk might help slow the process.

Usha Chakravarthy, professor of ophthalmology at Queen's University Belfast, gave a supplement containing vitamins C and E, zinc and the carotenoids lutein and zeaxanthin, which are found in leafy vegetables such as spinach, to volunteers. In the trial, which involved 400 people who had AMD in one eye and were at risk of losing their sight in the other, they found the supplement slowed the degeneration and sharpened vision.

"Late AMD causes severe sight loss and has a huge economic impact both in terms of the effects of sight loss itself and in terms of the expensive treatments that are needed to deal with the condition," said Chakravarthy, who is also a consultant ophthalmic surgeon at the Royal hospital in Belfast.
"We wanted to carry out the study as prevention of progression to late AMD can result in a reduced financial and societal burden."

The trial was designed after evidence from the US that supplements could help in AMD. A study in 2000 funded by the National Eye Institute in Bethesda found that people at risk of AMD who took nutritional supplements were less likely to lose their sight. The outcome came as a surprise, because vitamins and mineral supplements have been tried in a number of diseases with little success.
The US study got good results after five years. Chakravarthy's trial, at two sites in Northern Ireland and the Irish Republic, was meant to last for three years but ran out of funds. "We had to stop the study and analyse the findings," she said. "At the end of one year, there was no difference between the groups, but in those who had been in the study longer, we found there was a benefit in function."

Taking the totality of the evidence from her study and the American work, she believes antioxidants – either in supplements or through a diet rich in fresh fruit and leafy vegetables – can delay sight loss in people at risk from AMD.
A combination of exposure to sunlight, genetics and antioxidant levels in blood all have an effect on likelihood of the disease. "If your serum levels are high and your genetics are right and your exposure to sunlight is low, you are protected," she said.

She plans to explore the degree of protection further in the trial cohort.
Her advice to those at risk is to "stop smoking right away, go for a healthy diet and keep your cardiovascular system healthy, because they all contribute".