A cataract is a clouding of the lens in the eye leading to a decrease in vision. It can affect one or both eyes, it is more common with age, and can even lead to blindness. About 20 million people globally are blind due to cataracts. Vitamin supplements have failed to find an effect in numerous studies.
But in this study, eating foods rich in vitamin C and to a smaller degree manganese had the beneficial effect of slowing cataract progression over the course of 9 1/2 years. Manganese is a micronutrient that is necessary in small amounts, but it is rare to be deficient in manganese. However manganese has numerous negative effects if too much is ingested or if there is too much exposure. Bottom line: increased intake of fruit and vegetables (for vitamin C) could help prevent the development or progression of cataracts. From Medical Xpress:
Higher dietary intake of vitamin C has been found to have a potentially preventative effect on cataract progression in the first twin study of cataracts to examine to what degree genetic and environmental factors influence their progression with age. 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.
The study, led by King's College London and published in the journal Ophthalmology, looked at the progression of cataracts in the eyes of 324 pairs of female twins .... They found that those participants who had a higher intake of vitamin C were associated with a 33 per cent risk reduction 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, funded by the Wellcome Trust and Guide Dogs for the Blind, 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. 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.
Kate Yonova-Doing, the study's first author said: '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.'