WEBVTT - Do Carrots Really Help Your Eyesight? 0:00:02.040 --> 0:00:07.120 Welcome to brain stuff from how stuff works. Hey, brain stuff, 0:00:07.160 --> 0:00:10.440 Lauren vogel Bomb here. Anyone else have the common childhood 0:00:10.520 --> 0:00:12.600 dream to be able to hit clay pigeons with a 0:00:12.600 --> 0:00:15.400 crossbow in the dark at three yards while riding on 0:00:15.440 --> 0:00:19.560 the back of a beautiful pegasus. Just me. Anyway, When 0:00:19.600 --> 0:00:22.360 I told my parents this, they told me, Lauren, if 0:00:22.400 --> 0:00:25.120 you want to have that kind of hyper acute night vision, 0:00:25.360 --> 0:00:28.360 you've got to eat your carrots. It's common wisdom eat 0:00:28.360 --> 0:00:29.920 a lot of carrots if you want eyes like a 0:00:30.000 --> 0:00:33.440 jet pilot. But do carrots really give you better eyesight? 0:00:34.320 --> 0:00:36.960 The short answer is, if you already have enough vitamin 0:00:37.000 --> 0:00:39.920 A in your diet, probably not. But if you don't, 0:00:40.080 --> 0:00:42.279 a big old sack of carrots might be exactly what 0:00:42.360 --> 0:00:45.840 you need. Carrots are packed full of a nutrient called 0:00:45.880 --> 0:00:48.519 beta carotene, which is a kind of natural dye for 0:00:48.560 --> 0:00:51.800 fruits and vegetables. Plans use beta carotene in their bodies, 0:00:51.880 --> 0:00:54.480 is a pigment that gives them a yellow or orange color. 0:00:54.920 --> 0:00:57.360 But when you eat foods containing this natural pigment, like 0:00:57.480 --> 0:01:00.160 sweet potatoes, spinach, or carrots, the beta carrot he can 0:01:00.200 --> 0:01:03.400 gets absorbed by your intestinal wall and converted into vitamin A. 0:01:04.480 --> 0:01:07.120 So here's the true part of the myth. If you 0:01:07.160 --> 0:01:09.440 want to maintain normal eye health, you've got to get 0:01:09.560 --> 0:01:12.479 enough vitamin A, and carrots are a perfectly good source. 0:01:13.000 --> 0:01:15.000 In regions where people don't get much vitamin A and 0:01:15.040 --> 0:01:18.600 their diets, vision problems are rampant. Without vitamin A, the 0:01:18.600 --> 0:01:21.520 photo receptors in your eyes start to deteriorate and your 0:01:21.520 --> 0:01:25.600 corneas can actually vanish. But if you don't have a 0:01:25.680 --> 0:01:29.000 vitamin A deficiency and your vision is already healthy, stuffing 0:01:29.000 --> 0:01:30.960 your face with carrots or any other source of the 0:01:31.040 --> 0:01:35.479 vitamin will not lead to superhuman eyeball powers. So where 0:01:35.480 --> 0:01:37.440 did we get the idea that carrots can do to 0:01:37.480 --> 0:01:41.120 your eyes what spinach does to Popeye's forearms. Believe it 0:01:41.200 --> 0:01:43.600 or not, this myth got a big boost from World 0:01:43.600 --> 0:01:47.960 War two propaganda. During World War Two, the United Kingdom 0:01:48.040 --> 0:01:52.120 underwent air raids conducted by access powers. The German luft 0:01:52.120 --> 0:01:54.880 Buffa would strike at British cities in the night. Over 0:01:54.920 --> 0:01:57.680 the years, the British Royal Air Force had some success 0:01:57.680 --> 0:02:01.040 pushing back the German air attacks. An explanation for their 0:02:01.080 --> 0:02:04.680 success is that from nineteen thirty nine onward. British pilots 0:02:04.680 --> 0:02:08.840 had access to a technology called onboard airborne interception radar 0:02:09.080 --> 0:02:11.440 to help them spot enemy planes for a great distance, 0:02:12.040 --> 0:02:15.119 but the UK Ministry of Food launched a propaganda campaign 0:02:15.360 --> 0:02:18.079 claiming that its fighter pilots could pick out enemy aircraft 0:02:18.120 --> 0:02:21.120 in the dark because they honed their eyes with carrots. 0:02:22.040 --> 0:02:24.800 Some sources have speculated that this story was designed to 0:02:24.880 --> 0:02:27.400 hide the existence of the Royal Air Forces on board 0:02:27.480 --> 0:02:31.679 radar system from the enemy. Another explanation might be simple economics. 0:02:32.080 --> 0:02:35.680 Germans set up blockades to use starvation and discomfort as weapons, 0:02:35.840 --> 0:02:38.600 which meant that many goods like sugar, had to be rationed. 0:02:39.040 --> 0:02:42.679 The UK government encouraged its citizens to turn to sugar substitutes. 0:02:43.080 --> 0:02:46.119 For example, carrots, which were plentiful even during the war, 0:02:46.400 --> 0:02:48.799 could be used as a sweetener in foods like carrot 0:02:48.800 --> 0:02:51.880 pudding and carrot fudge, or as a substitute for meat 0:02:51.919 --> 0:02:55.680 in the infamous Wolton pie. Carrots were so plentiful because 0:02:55.680 --> 0:02:57.919 they could be grown by citizens at home and around 0:02:57.960 --> 0:03:01.880 their communities in so called victory gardens. Food supplies were 0:03:01.880 --> 0:03:04.720 low due to those blockades, and canned fruits and vegetables 0:03:04.800 --> 0:03:08.000 largely went to feed the military. Citizens were encouraged to 0:03:08.080 --> 0:03:10.560 make up the difference. The slogan of the campaign was 0:03:10.680 --> 0:03:14.680 dig for Victory. Two million private gardens were constructed and 0:03:14.760 --> 0:03:17.360 some public ones as well. The dry moat surrounding the 0:03:17.400 --> 0:03:25.760 Tower of London was filled in with growing vegetables. Today's 0:03:25.760 --> 0:03:28.560 episode was written by Joe McCormick and produced by Tyler Clang. 0:03:28.880 --> 0:03:30.880 For more on this and lots of other sharp topics, 0:03:30.960 --> 0:03:44.480 visit our home planet, how Stuff Works dot com.