Did the myth of carrots improving eye sight begin as WWII propaganda?

Question

I've often heard that the myth that eating carrots helps you see better at night (not to be confused with carrots helping with vitamin A deficiency) was started by the British in World War II, as propaganda to help conceal the fact that the RAF planes were equipped with radar. The story was that the RAF were able to find the German planes at night because their pilots were able to see very well in the dark due to eating a lot of carrots, and not because they were flying around with nifty gadgets.

The Smithsonian Magazine website summarized it:

During the 1940 Blitzkrieg [of Britain], the Luftwaffe often struck under the cover of darkness. In order to make it more difficult for the German planes to hit targets, the British government issued citywide blackouts. The Royal Air Force were able to repel the German fighters in part because of the development of a new, secret radar technology. The on-board Airborne Interception Radar (AI), first used by the RAF in 1939, had the ability to pinpoint enemy bombers before they reached the English Channel. But to keep that under wraps, according to Stolarczyk’s research pulled from the files of the Imperial War Museum, the Mass Observation Archive, and the UK National Archives, the Ministry provided another reason for their success: carrots.

Was this when the myth started? Or was the idea already out there in the public consciousness, and it was just exploited/popularized by the British Ministry of Information?

For example, were there popular writings from the '30s (newspapers, books, notable studies, etc) that were already making the leap from "vitamin A deficiency causes night blindness, so mega dosing vitamin A will enhance night vision", similar to the contemporary myth that "oxidants kill cells, so mega dosing antioxidants will keep you from aging"?

Answer 1

Please suggest improvements for the answer in the comments.

From the Smithsonian article cited in the question:

But to keep [British radar] under wraps, according to Stolarczyk’s research pulled from the files of the Imperial War Museum, the Mass Observation Archive, and the UK National Archives, the Ministry provided another reason for their success: carrots.

Basically, the story is saying that the myth of carrots improving eye sight begin as WWII propaganda to fool the Germans from believing the British had new radar systems. This is not true.

According to Scientific American (emphasis added):

But Bryan Legate, assistant curator at the Royal Air Force Museum in London has a different view. “I would say that whilst the [British] Air Ministry were happy to go along with the story [of carrot-improved vision], they never set out to use it to fool the Germans,” Legate says. “The German intelligence service were well aware of our ground-based radar installation and would not be surprised by the existence of radar in aircraft. In fact, the RAF were able to confirm the existence of German airborne radar simply by fitting commercial radios into a bomber and flying over France listening to the various radio frequencies!” he adds.

I contacted the World Carrot Museum as well as the RAF Museum. The correspondence supported the statements above. Ping me in chat/comments for the transcripts.

From the World Carrot Museum's dedicated page on the myth.

The truth is that whilst the British Air Ministry were happy to go along with the story of carrot-improved vision, they never set out to use it to fool the Germans.

and here

Famously, the UK Food Ministry responded to a temporary wartime oversupply of carrots by suggesting, through propaganda, that the RAF's exceptional night-flying and target success, was due to eating high carotene content carrots. The suggestion worked and the consumption of carrots increased sharply because people thought carrots might help them see better in the blackout, thus taking pressure off the food supplies.

Thus, the myth was introduced not to trick the Germans into believing the British didn't have airborne radar, but to encourage consumption of carrots when they were in excess and the British didn't have many food sources.

The Germans introduced countermeasures to airborne radar by 1942 (see here). They would have knew of their existence earlier.

Was this when the myth started?

The myth was popularized around this time in the hopes of increasing carrot consumption in the UK. As the myth was needed to increase carrot consumption, I assume the myth was either not widely known or nonexistent beforehand. However, I can't say when the myth started. Any search is populated with this particular incident of the myth; this version is definitely the most widely known.

Or was the idea already out there in the public consciousness, and it was just exploited/popularized by the British Ministry of Information?

The British Ministry of Information didn't popularize the myth or actively use it to "trick" the Germans into believing airborne radar didn't exist. By 1942, the Germans had already developed countermeasures to British airborne radar. To develop such countermeasures, British airborne radar, of course, had to have been known by the Germans.