Vitamins C and E are two of the antioxidants in the AREDS2 eye formula, at 500 mg of vitamin C and 400 IU of vitamin E. The full formula that includes them lowered the risk of moving from intermediate to advanced age-related macular degeneration (AMD) by about 25%, according to the National Eye Institute. On their own, the evidence is weaker, and large prevention trials found that neither vitamin prevents AMD in people who do not have it. Neither has been shown to prevent cataracts.
Vitamin C and vitamin E are familiar names. Most of us have heard that they are good for us, and both appear in AREDS2-style eye vitamins. But what did the research actually test, and what did it find for your eyes? This article walks through the trials, the numbers and the safety points in plain language.
For the other ingredients in the formula, see our guides to zinc and copper and lutein and zeaxanthin.
Where vitamins C and E fit in the eye formula
The NIH Office of Dietary Supplements (ODS) groups vitamins C and E with the antioxidants studied for eye health. The National Eye Institute (NEI) lists these doses in the AREDS2 formula, next to the amounts adults normally need each day:
| Nutrient | AREDS2 formula (NEI) | RDA for adults 51+ (ODS) | Upper limit for adults (ODS) |
|---|---|---|---|
| Vitamin C | 500 mg | Men 90 mg, women 75 mg | 2,000 mg |
| Vitamin E | 400 IU | 15 mg (men and women) | 1,000 mg |
ODS tables have no separate row for people over 51, so these are the adult rows that cover older adults. ODS also notes that people who smoke need 35 mg a day more vitamin C than people who do not.
What the AREDS trial found for the antioxidants
The first Age-Related Eye Disease Study (AREDS) enrolled 4,757 people aged 55 to 80. In its AMD trial, 3,640 people were followed for an average of 6.3 years. Participants were assigned to antioxidants (vitamin C, vitamin E and a carotenoid), zinc with copper, antioxidants plus zinc, or a placebo.
NEI reports these results compared with placebo:
- Full formula (antioxidants plus zinc and copper): 25% lower risk of progressing from intermediate to advanced AMD, and 19% lower risk of vision loss.
- Antioxidants alone: 17% lower risk of progressing, and 10% lower risk of vision loss.
The published report, AREDS Report No. 8, adds an important detail. For antioxidants alone, the odds ratio was 0.80, which was not statistically significant in the full group. In other words, the trial could not rule out chance for antioxidants taken without zinc. The full formula (odds ratio 0.72) did reach statistical significance. If odds ratios are new to you, our guide to the AREDS and AREDS2 trials explains them.
The fact sheets describe the combination this way. ODS says people with AMD who take antioxidant supplements that include vitamin C have a lower risk of progressing to advanced AMD. The ODS vitamin E fact sheet says the AREDS formulas "hold promise for slowing the progression of AMD" in people at high risk.
That benefit is limited to certain people. The NEI FAQ says the formulas benefited people with intermediate or late AMD, and there was no benefit for people with early AMD or without AMD. Read more in What Is AREDS2 and Who Needs It?
Can vitamin C or vitamin E prevent AMD?
This is where the evidence is clearest, and the answer is no. A Cochrane review (2017) looked at 5 randomized trials with 76,756 people from the general population, rather than people who already had AMD. The trials gave vitamins for years and counted who developed AMD.
A risk ratio of 1.0 means no difference from placebo. For vitamin E, the risk ratio was 0.97, based on high-certainty evidence. For vitamin C, tested in one trial, it was 0.96, and the review concluded that vitamin C probably does not prevent AMD either. Both ranges include 1.0, so neither showed a measurable prevention effect.
The fact sheets agree. The ODS vitamin C sheet says the evidence does not show that vitamin C, alone or with other antioxidants, affects the risk of developing AMD. The ODS vitamin E sheet notes that cohort studies linked higher vitamin E from food (about 20 mg a day) with roughly 20% lower AMD risk, but two supplement trials found no protective effect. ODS calls the overall evidence on prevention "inconsistent."
NEI states it directly: nutritional supplements cannot prevent AMD. Our article Can AREDS2 Prevent Macular Degeneration? covers what does help lower risk.
Vitamin C, vitamin E and cataracts
NEI's summary of the trials is clear: the AREDS and AREDS2 supplements do not have an effect on cataract. No AREDS formula reduced cataract surgery.
Some observational studies have linked higher vitamin C intake or higher blood levels with lower cataract risk, according to ODS. But studies like these cannot prove cause and effect, and one points the other way. In a group of 24,593 Swedish women aged 49 to 83, taking high-dose vitamin C supplements (about 1,000 mg a day) was linked to a 25% higher risk of cataract removal surgery. That was also an observational study, so it does not prove harm, but it is a reason not to assume more is better.
For vitamin E, ODS says some observational studies linked supplements or higher blood levels with clearer lenses or slower clouding of the lens. In AREDS, however, the vitamin E formula had no apparent effect on cataracts over 6.3 years, and AREDS2 confirmed this.
Reading vitamin E on a label: IU and mg
Vitamin E can be listed in international units (IU) or milligrams (mg), and the conversion depends on the form. The ODS vitamin E fact sheet explains the two forms you may see on a label:
| Form | Label name | 1 IU equals | 15 mg (the RDA) equals |
|---|---|---|---|
| Natural | d-alpha-tocopherol | 0.67 mg | 22.4 IU |
| Synthetic | dl-alpha-tocopherol | 0.45 mg | 33.3 IU |
A few things follow from this table:
- ODS describes the AREDS dose as 400 IU of dl-alpha-tocopheryl acetate, the synthetic form, which equals 180 mg.
- The upper limit of 1,000 mg a day equals 1,500 IU of the natural form or 1,100 IU of the synthetic form.
- The same number of IU gives you a different number of mg depending on the form. When comparing products, check which form is listed.
Our label comparison of AREDS2 supplements compares the amounts printed on common labels.
Food sources of vitamins C and E
These are top food sources listed in the ODS fact sheets:
| Vitamin C food | Amount | Vitamin E food | Amount |
|---|---|---|---|
| Red pepper, sweet, raw, ½ cup | 95 mg | Wheat germ oil, 1 tablespoon | 20.3 mg |
| Orange juice, ¾ cup | 93 mg | Sunflower seeds, dry roasted, 1 oz | 7.4 mg |
| Orange, 1 medium | 70 mg | Almonds, dry roasted, 1 oz | 6.8 mg |
| Grapefruit juice, ¾ cup | 70 mg | Sunflower oil, 1 tablespoon | 5.6 mg |
| Kiwifruit, 1 medium | 64 mg | Safflower oil, 1 tablespoon | 4.6 mg |
| Green pepper, sweet, raw, ½ cup | 60 mg | Hazelnuts, dry roasted, 1 oz | 4.3 mg |
Reaching the trial doses is a different matter. The NEI FAQ says the high levels in the AREDS formulas are difficult to get from diet alone. See Can You Get AREDS2 Nutrients From Food? for more.
Safety points for vitamins C and E
Vitamin C. The ODS vitamin C fact sheet says too much can cause diarrhea, nausea, stomach cramps and other stomach upset. It may raise the chance of kidney stones, especially in people with kidney problems, although the evidence is mixed. It could also worsen iron overload in people with hemochromatosis. ODS notes possible interactions with chemotherapy and radiation, and with simvastatin taken with niacin.
Vitamin E. The main concern is bleeding. ODS says large doses can raise bleeding risk in people taking blood thinners such as warfarin, probably at amounts above 400 IU a day. Two trials found more bleeding strokes in men taking vitamin E. The NEI FAQ says AREDS and AREDS2 found no adverse effects from 400 IU a day. It also notes that a separate trial, SELECT, found a 17% increase in prostate cancer with 400 IU a day for 7 years, while AREDS and AREDS2 found no effect on prostate cancer.
Keep in mind: If you take a blood thinner or simvastatin with niacin, or are having cancer treatment, or if you have kidney problems or hemochromatosis, talk with your doctor or pharmacist before starting a high-dose antioxidant formula. Our article on AREDS2 safety, side effects and interactions has a full checklist.
If you are comparing formulas, our science page lists the doses used in the trials.
Related reading
- Nutrition and Eye Health: What the Research Actually Shows
- 5 Vitamins and Nutrients That Matter for Your Eyes
- Zinc and Copper for Eye Health
- Can AREDS2 Prevent Macular Degeneration?
- The AREDS and AREDS2 Trials Explained
References
- Age-Related Eye Disease Study Research Group. AREDS Report No. 8. Arch Ophthalmol. 2001;119(10):1417-1436. doi:10.1001/archopht.119.10.1417
- Evans JR, Lawrenson JG. Antioxidant vitamin and mineral supplements for preventing age-related macular degeneration. Cochrane Database Syst Rev. 2017;7:CD000253. doi:10.1002/14651858.CD000253.pub4
- NIH Office of Dietary Supplements. Vitamin C: Fact Sheet for Health Professionals. Updated July 31, 2025. ods.od.nih.gov
- NIH Office of Dietary Supplements. Vitamin E: Fact Sheet for Health Professionals. Updated March 26, 2021. ods.od.nih.gov
- National Eye Institute. About AREDS and AREDS2. Updated October 22, 2025. nei.nih.gov
- National Eye Institute. AREDS/AREDS2 Frequently Asked Questions. Updated November 19, 2020. nei.nih.gov
This article is for general education and is not medical advice. Talk with your eye doctor before starting any supplement, especially if you smoke, take other medicines, or have a health condition. These statements have not been evaluated by the Food and Drug Administration. TruVista products are not intended to diagnose, treat, cure, or prevent any disease.
