Carrots and Night Vision - WW2

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WW2 - "Carrots Help you see in the dark"

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The Carrot is an economically important horticultural crop that has gained popularity since world War Two due to increased awareness of its nutritional value and versatility. Orange carrots are highly revered as “good for the eyes” due to their high content of hydrocarbon carotenoids, a class of phytochemicals that are often precursors to vitamin A. α- and β-Carotene predominate in orange carrots.

During the 6 years of World War Two the UK Ministry of Food did its best to drum up enthusiasm for carrots as a substitute for rationed goods. Doctor Carrot, carrying a bag marked " Vit A", was prominently featured on pages of recipe books and extensive advertising campaigns in the press, cinema and on the radio. 

World war Two revived the popularity of the carrot and gave it a rightful place in the kitchen, elevated to a new high as a major food and nutritional source.

Carrots also played their part in winning the air battle. Famously, the Government 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 ruse worked and consumption of carrots increased sharply because people thought carrots might help them see better in the blackout, thus taking the pressure off other food supplies.


"Carrots Help you See in the Dark" was a popular saying at the time and people eagerly digested carrots, Dr Carrot Arrives - The Children's Best Friendbelieving this would help them to see more clearly in the blackout. This ruse not only helped reduce the surplus vegetables but also helped to mask the chief reason for the RAF's success in night time air battles - the increasing power of radar and the secret introduction of an airborne version of the system. It is true that carrots can help keep your eyes healthy and if you are otherwise deficient in Vitamin A, will help you see better in the dark, by restoring that function to peak performance.

So, if you don't get enough carotene or Vitamin A in your diet, eventually you will suffer problems in your vision. This was the basis of the "myth" started by the Royal Air Force. Carrots cannot improve your eyesight, they can help maintain eye health. Even “Dr. Carrot” was depicted wearing glasses.


Carrots helped win World War Two in the air!

The carrot "myth", which is not!  - It is said that UK World War Two pilots were fed excessive amounts of high carotene carrots to help them see better in the dark and therefore spot, and shoot down enemy airplanes quicker. Famously, the Government responded to a temporary wartime oversupply of carrots by suggesting that the RAF's exceptional night-flying success was due to consuming more carotene, via carrots. The ruse worked: consumption of carrots increased sharply because people thought carrots might help them see in the blackout, thus taking the pressure off other food supplies.

At one point in the early 40's there was a glut of carrots, and the Government let it be known that carotene, which is believed to help (or restore) night vision, was largely responsible for the RAF's increasing success in shooting down enemy bombers. People eagerly tucked in to carrots, believing this would also help them to see more clearly in the blackout. The ruse not only reduced the surplus vegetables but also helped to mask the chief reason for the RAF's success - the increasing power of radar and the secret introduction of an airborne version of the system.

The slogan "Carrots keep you healthy and help you see in the blackout" was used extensively. Advert (right) from the UK Times, 6 February,1942.

Here is what the RAF Museum in London has to say on the myth -

"We have not, as of yet, found any official paperwork or correspondence in our collections relating to any officially organised attempt by the Air Ministry or RAF to convince the Germans our night fighter successes were down to carrot consumption.

The public were almost entirely unaware of the concept of radar as it was officially secret (they could see the various sites around the south coast but didn’t know what they were for), the Germans however were well aware of their function, as evidenced by the effort put in to see if they could be knocked out during the Battle of Britain.

It’s reasonable to assume that when John Cunningham started racking up his score against the night bombers that had been terrorizing the public, it would make a great morale boosting story; but neither he, nor the RAF, were at liberty to say why he was so successful – the Germans may well have known half the story, that ground based radar stations vectored his aircraft into the vicinity of the bombers, the public were not even aware of this much.

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. The German intelligence service were well aware of our ground-based radar installations 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!

The UK RAF Museum, in London, has no paperwork relating to this first press release (which would have been handled through the Ministry of Information anyway) so who first mentioned the idea of using the carrot story may remain a mystery, unless any files are still held at the National Archives. Whether or not the Ministry of Food were responsible for the original story, they certainly made use of it getting Cunningham to endorse carrots to the population. The lack of any follow on from the RAF, and no effort to really get the Germans to believe it was carrots rather than radar that allowed our night fighters to be as successful as they were, leads me to believe that the Air Ministry were just happy to “go with the flow”, as it were, and follow the lead set by the MoI.

It seems far more likely that the publicity campaign was intended more for the people at home than for the Germans, and an attempt to convince the public to use a readily available home grown food to replace things that would otherwise have been imported."

In the US the Popular Science magazine reported in May 1942 thus:

Flyers are Redesigned - The new challenges of fighter pilots achieving successful missions in almost total darkness gave the flight doctors some challenges.  The photochemistry of night vision is still mysterious but it is thought to be intimately connected with Vitamin A in the diet. Vitamin A deficiency causes exophthalmia , an eye inflammation commonly associated with nigh blindness; but the Air Forces are interested in something much less obvious than that.

In the retina of the eye is a pigment known as visual purple, very sensitive to dim light, formed by a combination of vitamins A with certain proteins. Light bleaches out the visual purple in the eye. the theory is that adaptation to darkness depends on the amount of visual purple stored, and that glare blinds us by bleaching it out. Blindness follows glare until the pigment is restored.

Whether or not this is the final solution, flight surgeons heavily load the diet of pilots with butter, eggs, carrots and spinach to supply large quantities of Vitamin A. The pilots grumble good humouredly about “duty food” and put away large platefuls of salad greens. (extract, full version available here - Popular Science archives)

Facts:
 - The First radar system was produced in 1935 by Sir Robert Watson-Watt

 - By 1939, UK had radar stations all round the south coast of the UK

 - In 1940, John Cunningham was the first pilot to down an enemy using radar

 - To cover-up the use of on board radar from the Germans, pilots were praised for being able to see in the dark through a "secret" diet

 - The government said it was because they ate carrots, rich in Vitamin A.

There is very little hard evidence for this propaganda exercise, but it is fairly clear it did take place. For example in the book "The Fear in the Sky: Vivid Memories of Bomber Aircrew in World War Two" by Pat Cunningham, he said:

"One extracurricular activity this time around at Yatesbury involved the disinformation that night-fighter pilots were fed on carrots to improve their night vision. This, of course, was aimed at covering up the fact that the RAF possessed radar. Whether the authorities had begun to believe their own propaganda, I couldn't say, but the Yatesbury intakes were used as guinea pigs. Our class was fed carrots until we were sick of them, whereas other classes had none. But although it went on for some weeks I never heard that anything came out of it one way or another." 

How the myth became confused, although it has some truth behind it - For the record, carrots CAN help you see better in the dark. Carrots are good for your eye health (not eyesight) and in one area can be a cure for night blindness! if you are otherwise deficient in Vitamin A.

Night blindness (nyctalopia) is the inability to see well at night or in poor light. It is not a disorder in itself, but rather a symptom of an underlying disorder or problem. It can have several causes and Vitamin A deficiency is one of them. It is rare in Western society, that does not mean it does not exist. The consumption of carrots in such circumstances will help cure the symptom and help the sufferer see better in the dark, by restoring night vision to its normal level.

In 1940 experiments with high carotene varieties were conducted to reduce night blindness in World War II pilots. These high carotene roots were very dry. With the advent of synthetically manufactured carotene, cultivation of these varieties ceased in 1947. In World War II, Britain's Air Ministry spread the word that a diet of carrots helped pilots see German bombers attacking at night. That was a lie intended to cover the real matter of what was underpinning the Royal Air Force's successes: the latest, highly efficient on board,  Airborne Interception Radar, also known as AI. The secret new system pinpointed some enemy bombers before they reached the English Channel.

When the Luftwaffe's bombing assault switched to night raids after the unsuccessful daylight campaign, British Intelligence didn't want the Germans to find out about the superior new technology helping protect the nation, so they created a rumour to afford a somewhat plausible-sounding explanation for the sudden increase in bombers being shot down. British Intelligence instigated news in the British press about extraordinary personnel manning the defences, including Flight Lieutenant John Cunningham, an RAF fighter pilot dubbed "Cats Eyes" on the basis of his exceptional night vision that allowed him to spot his prey in the dark. In fact, in WW II, he was the RAF's top-scoring night fighter pilot, with a total of 20 kills. Cunningham's abilities were chalked up to his love of carrots.  The Royal Air Force bragged that the great accuracy of British fighter pilots at night was a result of them being fed enormous quantities of carrots and the Germans bought it because their folk wisdom included the same myth.

But this story was only a myth invented by the RAF to hide their use of radar, which was what really located the Luftwaffe bombers at night - not human carrot-assisted super-vision.

It is true they can help you see better in the dark, BUT can only improve your night vision, by defeating night blindness if you are otherwise deficient in Vitamin A.  When you eat carrots, the beta-carotene is transformed into retinol or vitamin Carrots are high in Vitamin A, and a deficiency in this nutrient can cause some difficulty seeing in dim light. Vitamin A is essential for the formatDig For Victory Poster Carrotsion of the chemical retinal, whose presence in the retina is necessary for vision. Our eyes have two kinds of light sensitive cells: the rods and the cones. The rods are the cells we rely on to see in dim light.

They are sensitive to Vitamin A deficiency, because it can cause a shortage of retinal. The retina is the light-sensing part of the eye that holds the rods and cones, which contain enzymes that absorb light and allow us to see. When light strikes the retinal molecule, it changes its shape. This activates a cascade of chemical reactions that informs the brain that light has entered the eye. When the levels of light sensitive molecules are low, due to Vitamin A deficiency, there will not be enough retinal to detect the light at night. During the day there is enough light to produce vision, despite low levels of retinal.

So it's only night vision that can be improved by eating carrots. The rods provide black and white vision and respond in dim light while the cones provide colour vision and respond to bright light. Vitamin A helps the retina tell black from white and provides for colour vision. It also helps us see in dim light or at night. When you go into a darkened theatre after being out in the bright light, your eyes are able to adapt because of the vitamin A that you have stored in your body.

So really the answer is they do help you see in the dark, but can only improve your night vision if you are deficient in Vitamin A. All that the correct level of Vitamin A in the body can do, is restore night vision to peak performance.

The disinformation was so persuasive that the English public to the extent that they started growing and eating more carrots, so that they could find they way around easier at night during the blackouts that were compulsory during WW II.

According to the World Health Organization (WHO), "vitamin A deficiency (VAD) is the leading cause of preventable blindness in children." In fact, WHO estimates that 250 million young children, and an unknown but substantial number of pregnant women, are vitamin A deficient worldwide. Read more on the Vitamin A page.


How the "myth" became misunderstood - It is pretty clear that beta carotene is good for eye health and easily available from carrots. Carrots are of course not the only source of Vitamin A. There is a difference between eye sight and eye health.

Eye Sight – is about visual acuity and whether a person can see everything, near and far, in sharp focus. Poor eye sight is often a physical trait. Once Night blindness is cured you can see better in the dark. Items will be not better focussed as that is a function of good eyesight.

Eye Health -. It is possible to have good eye health yet poor vision.  Less likely to have poor eye health and good eye sight.

As many UK citizens were not deficient in Vitamin A, the higher consumption made no difference they claimed that is was a myth promoted by the government to convince the to eat more carrots. All that the correct level of Vitamin A in the body can do, is restore night vision to peak performance.

Transcript of an actual "Kitchen Front" radio broadcast script (pdf) which addresses night blindness here.

 

Report from US Time Magazine 22 December 1941:

The R.A.F. may soon be eating Arizona carrots in preference to all other carrots on earth. The British Ministry of Foods last week impatiently cabled to University of Arizona Nutrition Chemist Margaret Cammack Smith for more details on her discovery that "Arizona carrots contain three to ten times as much carotene as the average carrot" - a discovery, said the Ministry, "of extreme interest and value." Reason: carotene, a yellow pigment occurring in association with chlorophyll in green plants, is transformed by the body (probably the liver) into vitamin A, which insures optimum human night vision.


Read more about night blindness at the US National Library of Medicine here.

See the full story of "Cats Eyes" Cunningham here.

World War Two also produced a genuine Carrot plane! - read more here.

The benefits of carrots to night vision was also covered in the antipodes - copies of Australian and New Zealand newspapers -

The Argus (Melbourne, Vic, 21 June 1941 (Australia) WAR FLYING Evening Post, Volume CXXXII, Issue 131, 29 November 1941 (New Zealand)


NOTE: The majority of the information in this page has been drawn from the archives material in the Imperial War Museum (UK), The UK National Archives (Kew, London) and the Mass observation Archives located at Sussex University. Reference material is here.


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