Increased dietary vitamin C may protect against cataract

Higher intake of vitamin C in the diet may potentially prevent progression of cataract, a new study in twins has found.
Cataract is a common condition in which the lens of the eye becomes cloudy as a result of oxidation over time. Whilst this is a natural part of ageing for many, for others it is more severe and causes blurred vision, glare and dazzle that cannot be corrected by glasses or contact lenses.
Researchers from King's College London looked at the progression of cataracts in the eyes of 324 pairs of female twins from the Twins UK registry over 10 years by examining photographs of the participant's lenses that allowed them to analyse the level of opacity of the lens in detail.

Participant intake of vitamin C was also measured using a food questionnaire.
They found that those participants who had a higher intake of vitamin C were associated with a 33 per cent reduced risk of cataract progression and had 'clearer' lenses after the 10 years than those who had consumed less vitamin C as part of their diet.
The study also found that environmental factors (including diet) influenced cataract more than genetic factors, which only explained a third of the change in lens opacity.

The fluid in the eye that bathes the lens is high in vitamin C, which helps to stop the lens from oxidising and protects it from becoming cloudy, researchers said.

It is thought that increased intake of vitamin C has a protective effect on cataract progression by increasing the vitamin C available in the eye fluid, they said.
"The findings of this study could have significant impact, particularly for the ageing population globally by suggesting that simple dietary changes such as increased intake of fruit and vegetables as part of a healthier diet could help protect them from cataracts," said Chris Hammond from King's College.
"While we cannot avoid getting older, diabetes and smoking are also risk factors for this type of cataract, and so a healthy balanced diet and lifestyle generally should reduce the risk of needing a cataract operation," said Hammond.

"The human body cannot manufacture vitamin C, so we depend on vitamins in the food we eat. We did not find a significantly reduced risk in people who took vitamin tablets, so it seems that a healthy diet is better than supplements," added Kate Yonova-Doing from King's College.
The findings were published in the journal Ophthalmology.