Eating foods high in vitamin C can cut the risk of cataract progression by a third, says new research.
The study, published in the journal Ophthalmology, is the first to suggest that genetic factors may be less important in progression of the condition than previously thought.
Cataracts, the leading cause of blindness globally despite the advent of modern surgery to remove them, occur naturally with age and cloud the eye's lens, turning it opaque.
Researchers at King's College London looked at whether certain nutrients could help prevent cataract progression.
They examined data from more than 1000 UK pairs of female twins who answered a food questionnaire tracking their intake of vitamin C and other nutrients.
To measure the progression of cataracts, digital imaging was used to check the opacity of their lenses at around age 60.
A follow-up measurement on 324 pairs of the twins was carried out about 10 years later.
During the baseline measurement, diets rich in vitamin C were associated with a 20 per cent risk reduction for cataract.
After a decade, the researchers found that women who reported consuming more vitamin C-rich foods had a 33 per cent risk reduction of cataract progression.
Genetic factors accounted for 35 per cent of the difference in cataract progression, while environmental factors, such as diet, accounted for 65 per cent.
"While we cannot totally avoid developing cataracts, we may be able to delay their onset and keep them from worsening significantly by eating a diet rich in vitamin C," said study author Professor Christopher Hammond.
The reason may be related to vitamin c's strength as an antioxidant, say the researchers.
The fluid inside the eye is normally high in vitamin C, which helps prevent oxidation that clouds the lens.
More vitamin C in the diet may increase the amount present in the fluid around the lens, providing extra protection.
The study's findings only related to consuming the nutrient through food and not vitamin supplements.
