The evidence base

AREDS And AREDS2: The Trials Behind Every Eye Supplement

Almost every eye supplement on the market borrows its credibility from two trials, and almost none of them carries the amounts those trials used. Here is what AREDS and AREDS2 were, in whom they were run, what they found, and what the phrase "AREDS2 formula" on a label does and does not mean.

By OptiCore Pro Team · Last updated October 29, 2026 · 9 min read · The evidence base · Reviewed by Dr. Catherine Sheils, MD

The 2001 trial, and why it was unusual

Nutritional supplements are rarely tested the way drugs are. The Age-Related Eye Disease Study was an exception: a randomised, placebo-controlled trial run by the National Eye Institute across eleven centres, following 3,640 people for an average of more than six years.

The formulation was deliberately aggressive. Vitamin C 500 mg, vitamin E 400 IU, beta-carotene 15 mg, zinc 80 mg as zinc oxide and copper 2 mg as cupric oxide, taken every day. Those are not maintenance amounts and they were never intended to be.

The result was modest and real. In participants with intermediate or advanced disease in one eye, the combination reduced the risk of progressing to advanced macular degeneration over five years. In participants with no or early signs, it did nothing measurable.

The two middle columns are the published trial formulations. The right-hand column is a typical range for an ordinary multivitamin and is there for scale.

What AREDS2 changed, and why

AREDS2 was published twelve years later and set out to improve the original in two ways. It asked whether lutein and zeaxanthin could replace beta-carotene, and whether adding omega-3 fatty acids helped.

The lutein and zeaxanthin question was answered in the affirmative, at 10 mg and 2 mg a day. The substitution performed comparably to beta-carotene and carried none of its baggage, which is why the modern formulation is the one with the carotenoids in it.

The omega-3 question was answered in the negative. DHA 350 mg and EPA 650 mg a day added nothing to the progression endpoint. That is a clean null from a well-powered trial, and it is the reason a fish oil capsule is not part of the standard formulation.

A separate report from the same trial looked at lutein and zeaxanthin for cataract, and a ten-year follow-up confirmed that the substitution held up over a much longer horizon. The National Eye Institute's own page prints both formulations ingredient by ingredient and is free to read.

Who these trials were actually run in

This is the part most often dropped, and it changes what the results mean for somebody reading a label in a shop.

Every row is about people who already had macular changes, except the last. That distinction is the one most often dropped when these trials are quoted.

Everybody in AREDS and AREDS2 already had macular changes. The trials measured whether a high-dose formulation slowed the progression of an existing condition, not whether it improved vision, sharpened sight or prevented anything from starting.

That last question was asked separately and answered separately. A Cochrane review of prevention looked at whether antioxidant vitamins and minerals stop age-related macular degeneration developing in people who do not have it, and found no evidence that they do.

Why beta-carotene left the formula

The reason has nothing to do with eyes. It comes from two large cancer prevention trials that were running in parallel with the first eye study.

The ATBC trial gave 20 mg of beta-carotene a day to 29,133 male smokers and reported more lung cancer in the beta-carotene arm, not less. The CARET trial gave 30 mg with retinyl palmitate and was stopped twenty-one months early for the same signal.

Those findings did not overturn the eye result, but they made a 15 mg daily dose of beta-carotene an uncomfortable thing to recommend to a population that includes former smokers. Replacing it with two carotenoids that concentrate in the macula and carry no such signal was the obvious improvement, and it is what AREDS2 tested.

The zinc question, and the useful number

Zinc is the mineral most associated with this category and 80 mg a day is the figure everybody quotes. It is also an amount almost no supplement carries, because 80 mg is more than seven Daily Values and is not a maintenance dose.

AREDS2's second arm is more useful for reading a label. It tested 25 mg against 80 mg and found the lower amount performed as well. Twenty-five milligrams is a figure a real supplement might plausibly carry, which makes it the right benchmark for anybody comparing bottles.

Copper travels with zinc in both formulations for one specific reason: sustained high-dose zinc depletes copper through competitive absorption. That is why a label carrying large amounts of zinc without copper is worth a second look, and why a label carrying a modest amount of zinc raises no such question.

• 80 mg is the headline figure and is almost never found on a shelf product.
• 25 mg is the amount that performed equally well and is the practical benchmark.
• Copper at 2 mg is there to offset the zinc, not for its own sake.
• Below roughly 25 mg of zinc, the copper question does not arise at all.

The question the trials did not answer

Somebody in their forties, spending nine hours a day at a screen, with no diagnosed eye condition, is the person most eye supplements are actually sold to. Neither trial says anything about that person.

The honest position is that the evidence for supplementation in healthy eyes is absent rather than negative. Nobody has shown these nutrients prevent anything in people who do not have the condition, and the review that looked specifically found no evidence for it.

That does not make a daily multivitamin a bad purchase for somebody whose diet is narrow. It makes the reason for buying one nutritional adequacy rather than disease prevention, and those are different arguments with different evidence behind them.

Reading AREDS2 on a label

The phrase appears on a great many bottles and it is not a protected term. Three readings are common and only one of them is accurate.

A genuine AREDS2 formulation

Carries all six ingredients at the trial amounts: vitamin C 500 mg, vitamin E 400 IU, lutein 10 mg, zeaxanthin 2 mg, zinc at 80 or 25 mg, copper 2 mg. These exist, usually sold through pharmacies and often described as being for people with a diagnosis.

AREDS2-based, or AREDS2-inspired

Usually means some of the ingredients at some of the amounts. The phrase has no definition, so the only way to know is to read the panel and do the arithmetic against the table near the top of this article.

Neither, but sold in the same aisle

A broad multivitamin with an eye-shaped label, which is the largest group by a distance and includes the product sold on this website. OptiCore Pro carries vitamin C at 60 mg, vitamin E at 7 mg and zinc at 3.62 mg, and no lutein, zeaxanthin or copper at all. That is a different kind of object from the two columns above and this desk says so on every page where it is relevant.

The practical advice fits in a sentence. If a bottle claims the trial's authority, check the trial's amounts, because the claim is free and the amounts are not.

The scorecard on the choosing a vision supplement page turns that into ten checks you can run on anything.

References