Research conducted during the Age-Related Eye Disease Study (AREDS) found that vitamin C may protect eyesight by reducing the risk of cataracts, and together with other important nutrients, may slow down the progression of what is called age-related macular degeneration (AMD) and loss of visual acuity, according to the American Optometric Association. Considering that more than 25 million people suffer from AMD and cataract formation, potential cures or preventative measures are worth exploring.
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This large trial was carried out at 11 different centres in the USA. Subjects were selected if they suffered from AMD in various stages. These participants were randomly divided into four groups and given oral tablets on a daily basis containing either antioxidants (500 mg vitamin C; 400 IU vitamin E; and 15 mg of beta-carotene [the precursor of vitamin A]) or 80 mg of zinc and 2 mg of copper, or the listed antioxidants plus zinc, or placebo (dummy treatment) .
The more than 3,600 patients between the ages of 55 and 80 years, were on average followed up for 6.3 years.
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ARED study results
When the results of the eye examinations of the treated patients were compared to those of the placebo group, the group receiving antioxidants plus zinc had a 72% reduction in development of advanced AMD, a result that was highly significant. However the group that were treated with antioxidants alone had an even better result with an 80% reduction in development of advanced AMD.
The team conducting this extensive study, therefore, concluded that “Persons older than 55 years should have dilated eye examinations to determine their risk of developing advanced AMD.” In addition, those with symptoms indicating AMD should consider taking a supplement of antioxidants and zinc as used in the ARED Study.
The AOA (American Optometric Association) (2015), also emphasised that ensuring an adequate vitamin C intake may help to prevent cataracts. One study reported that female participants who had taken vitamin C supplements for 10 or more years had a 64% reduction in the risk of developing cataracts.
Other studies found similar results and recommended that intakes of 300 mg of vitamin C per day appeared to be the minimum amount required to achieve eye health, but that this type of intake had to be used for 10 or more years to make a significant difference.
Read: Vitamin C lowers cataract risk
The pros and cons
As always, researchers query the findings of studies such as AREDS. Lawrenson and Grzybowski recently published a review of nutritional supplements that are taken by the general population for a variety of ailments, including to improve eye health. The eye conditions these authors investigated were the 3 most common eye problem suffered by older patients, namely AMD, dry eye syndrome and cataracts.
Their investigation indicated that the high quality evidence obtained with the AREDS trial did show that the use of beta-carotene, vitamin E, vitamin C and zinc could slow down the development of AMD. More recent results from the AREDS2 trials suggest that the beta-carotene supplement could be replaced by lutein and zeaxanthin (two nutrients that have long been known to benefit eye health).
Quiz: Do you need a vitamin C supplement?
Foods rich in Vitamin C
While most people will reach for vitamin supplements, the American Optometric Association (AOA) sensibly also encourages patients to (if possible), use food sources of vitamin C to obtain the required 300 mg of vitamin C per day by including the following rich sources of ascorbic acid in their diets:
- All citrus fruits including oranges and freshly squeeze orange juice (124 mg vit C/cup), grapefruit and fresh grapefruit juice (94 mg vit C/cup), lemons, limes, naartjies, tangelos, clementines.
- Guavas, and all berry fruits (strawberries, blueberries, blackcurrants, fresh cranberries, gooseberries)
- Tomatoes (fresh and cooked)
- Spinach and the cabbage family, including broccoli, green cabbage, Brussels sprouts, Chinese cabbage and sauerkraut
Dieticians encourage us to include at least one serving of a vitamin C-rich fruit or vegetable a day, but if you have a citrus fruit for breakfast, and some tomato in your salad at midday and steamed broccoli at dinner you will probably obtain enough vitamin C from your diet to protect your eyes against macular degeneration, cataracts and dry eye syndrome.
If you feel that your eyesight is deteriorating, have an eye test and discuss the use of natural or supplemental vitamin C and other eye-protective nutrients with your medical doctor and dietician.
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Rosemary protects against macular degenerationImage: Fresh citrus fruit from Shutterstock
- Age-Related Eye Disease Study Research Group, 2001. A randomised, placebo-controlled, clinical trial of high-dose supplementation with vitamins C and E, beta carotene, and zinc for age-related macular degeneration and vision loss: AREDS report no. 8.
- Lawrenson & Grzybowski, (2015), Controversies in the use of nutritional supplements in ophthalmology. Curr Pharm Des, 2015, (Sep 8).