A sliced carrot looks like an eye. That's not why it helps

Maybe night driving has gotten harder. The headlights glare. The back roads seem darker than they used to.

Or your eye doctor said the words "macular degeneration," and now you stand in the drugstore aisle staring at eye vitamins.

Somebody has told you to eat your carrots. Here's what holds up in that advice, and where the eye trials point instead…

Cut a carrot straight across and look at the slice. You'll see an orange ring around a paler core, with faint lines running out from the middle. It looks a lot like the colored part of your eye.

Folk wisdom calls that a sign, under the old Doctrine of Signatures: a plant's look shows which part of the body it serves.

So I went looking for the old source. Nicholas Culpeper's herbal of 1653 has a full entry on the carrot. It talks about gas and stones. Eyes never come up. The match shows up on modern websites, not in any old herbal I could find…

The Slice Proves Nothing

So does the slice tell you anything about your eyes? It doesn't. A look-alike is a memory trick, not a mechanism.

The real tie between carrots and eyes is much younger. It comes from a war.

The Pilot They Called Cat's Eyes

In the fall of 1940, German bombers came over Britain night after night. The Royal Air Force needed pilots who could find them in the dark.

One of the best was John Cunningham of No. 604 Squadron. On the night of November 19, 1940, he shot down a German bomber. Soon he had a nickname: Cat's Eyes.

His real edge was a radar set on board, run by Jimmy Rawnsley.

Britain's Ministry of Food had its own push going. Its posters said carrots could help you see in the blackout. A cartoon figure named Dr. Carrot joined the drive.

You may have heard the carrot talk was a trick to hide the radar. But a historian at the Royal Air Force Museum has said the Germans already knew about British radar. The carrot push was mostly a food drive aimed at people at home.

Still, the posters had one thing half right. Vitamin A really does run your night vision. It just can't give you a cat's eyes…

Where Night Blindness Comes From

At the back of your eye, a pigment called rhodopsin lets you see in dim light. Your body builds it from a form of vitamin A.

Run short on vitamin A and dim light goes first. The Linus Pauling Institute at Oregon State University calls night blindness the first sign that you're short.

People knew a fix long before they knew the cause. Hippocrates gave raw beef liver soaked in honey, by mouth. An Egyptian papyrus from about 1500 BC lists roasted ox liver for an eye problem, though scholars argue over whether that problem was night blindness. Liver is packed with vitamin A.

And this is not just history. The World Health Organization estimates that 250,000 to 500,000 children short on vitamin A go blind every year. Half of them die within 12 months of losing their sight.

The Doctor Who Followed The Kids

Alfred Sommer, an eye doctor at Johns Hopkins, was studying children in Indonesia. He saw something odd. Kids with night blindness at one exam were less likely to show up for the next one, three months later.

So he ran a test. In Aceh, in northern Sumatra, 450 villages were split into two groups. Children in one group got a big vitamin A capsule. The other villages waited a year.

Deaths among the young children ran 49 percent higher in the villages without the capsules. The trial covered 25,939 children, and it ran in The Lancet in 1986. That was a capsule, not a carrot.

Here's where carrots come in. Their orange pigment, beta-carotene, is something your body turns into vitamin A. Call it the orange pigment from here on.

One medium raw carrot gives about 509 micrograms of vitamin A, per the U.S. Department of Agriculture. That's more than half of what a man needs in a day.

But more is not better once you have enough. The American Academy of Ophthalmology says foods rich in vitamin A help you keep good sight, but they won't make your vision better or keep you out of glasses.

What The Eye Trials Found

The bigger worry past 55 is age-related macular degeneration, or AMD. It wears down the macula, the small spot at the center of your retina that gives you sharp sight.

The National Eye Institute tested pills. Its big eye disease study followed 3,640 people aged 55 to 80. One pill held vitamin C, vitamin E, 15 mg of the orange pigment, zinc and copper.

Bausch and Lomb, which sells eye vitamins, helped fund that trial.

Then came a second trial. Emily Chew at the National Eye Institute led its 2013 report on 4,203 people. Adding lutein and zeaxanthin, two yellow pigments found in greens, did not lower the risk further in the main test. Call them the eye pigments from here on.

The orange pigment arm had a problem, though. It turned up 23 lung cancers, against 11 without it, mostly in former smokers. So the formula swapped the orange pigment out for the eye pigments.

A 2022 follow-up found the eye pigments did about 15 percent better than the orange pigment at slowing AMD. That follow-up only watched people, and Bausch and Lomb supplied the pills for five years.

The Pigments Your Macula Uses

Here's the part the carrot story leaves out. The eye pigments gather in the macula itself. And carrots carry very little of them.

Per the same federal data, 100 grams of raw spinach holds about 12,200 micrograms of the eye pigments. The same weight of raw carrot holds about 256. That's nearly 48 times more in the spinach.

In 2015, a Harvard team reported on 102,046 nurses and health workers tracked for about 25 years. People in the top fifth for the eye pigments had about 40 percent less advanced AMD than the bottom fifth.

That study only watched what people ate. It shows a link, not proof.

What about food itself? I found no trial that tested carrots, or spinach, against AMD. Nobody has run one…

Three Things Worth Knowing At The Stove

A carrot slice looks like an eye. That's fun to show a grandchild. But it proves nothing.

John Cunningham found his bombers with radar, not carrots. What the carrot does give you is vitamin A, the stuff your night vision is built from. For the center of your eye, the trials point to the dark green leaf beside it.

Cook your carrots in a little oil this week. Then put a pile of spinach right next to them.

Stay well,
The Healing Plate