During World War II, the British Royal Air Force boasted an impressive accuracy in intercepting Nazi German bombers despite the cover of darkness at night. The British air ministry reported that their fighter pilots ate a large amount of carrots to boost their night vision. Since then, it has become public knowledge that carrots help you see better in the dark.
Unfortunately, this is false. The British air force were not actually using carrots to help see better in the dark; they were using a revolutionary new technology called radar to spot enemy war planes from a far distance. The carrot propaganda was spread to hide this fact from the Germans.
The carrot myth sounds plausible as carrots contain a large amount of beta-carotene, which is converted into vitamin A in the body. Vitamin A is a key chemical required for vision, in the form of retinal. It is true that vitamin A deficiency can cause night blindness. However, the dose of vitamin A required to improve your night vision is so high that it cannot be achieved by simply eating a lot of carrots.
Factoids are commonly known as trivial tidbits of knowledge and fact. This is actually incorrect. Factoids actually mean pieces of false information that have circulated and become popular to the point that they are accepted as facts. This makes factoids ironic in the sense that the definition of a factoid itself, is a factoid.
Here are several examples of common factoids.
“Vikings wore horns on their helmets”.
There is no evidence of this ever happening and all Viking helmets found in archaeology are hornless. It is likely a myth originating from dramatisation of the Vikings in opera.
“Medieval people thought the Earth was flat”.
It has been common knowledge that the Earth is spherical even since ancient Greek times. Greek astronomer Eratosthenes even calculated the Earth’s circumference to within 5-15% error margin of the actual circumference in 240BC.
“Napoleon Bonaparte was short”.
Napoleon’s height was recorded as 5 feet 2 inches, but this is in fact French feet. This converts to 5 feet 7 inches, which is taller than the average height for French males at the time.
“The low life expectancy in the Middle Ages meant people usually died around their 30’s”.
The low life expectancy of the past was mostly due to the high infant mortality, meaning people who survived into adulthood lived much longer, fuller lives.
“You need to drink eight glasses of water to stay healthy”.
There is no agreed upon amount of water a person should drink in medical literature. The current consensus is that drinking water when you feel thirsty is fully sufficient to avoid dehydration.
“Carrots help you see in the dark”.
Vitamin A is indeed used by the body to synthesise chemicals used in vision, but having more does not improve your vision. This was a myth propagated by Great Britain during World War 2 to mask the fact that they were using radar for accurate nighttime bombings.
“Evolution is a theory, meaning there is insufficient evidence to confirm it”.
This is a complete misunderstanding shared by many people against evolution. The word “theory” in science means a concept or set of principles that best explains an observed phenomena, not a hunch as it is often used in common English. For example, gravity is a theory, as well as germ theory (that microorganisms cause infectious diseases).
“Chameleons can change the colour of their skin to match their surroundings”.
Chameleon’s skin colours change based on their mood, not the colour of their surroundings. Cuttlefish, on the other hand, can perfectly mimic and blend in to their surrounding environment.
“Adding oil when boiling pasta stops sticking”.
The oil floats to the top and does nothing to prevent sticking. Adding oil after draining the water will help.
“Searing meat seals in the juices”.
Searing can actually make meat drier on average. It does, however, add more flavour by adding a brown crust due to the Maillard reaction.
The world is full of people of all creed and races and it is a common fact that people from certain races have different skin colours to people from other races. But other than the range of normal skin colours, there are certain skin colours that can occur with specific medical conditions.
The most common reason for a change in skin colour is a suntan, which damages the skin and causes darkening of the skin (hyperpigmentation). However, some diseases are also known to cause hyperpigmentation, such as Addison’s disease or haemochromatosis.
The converse is lightening of the skin (hypopigmentation) and can happen with diseases such as leprosy, vitiligo or albinism. Alternatively, people can look pale when they are anaemic or extremely frightened, triggering a sympathetic nervous response, shutting down blood circulation to the face and extremities.
It is common to see red skin with flushing, sunburns, skin infections or numerous dermatological conditions such as rashes. Occasionally, these rashes may be associated with serious diseases such as lupus or Crohn’s disease.
Cyanosis (literally “blueness” in Latin) causes the skin to bluish-purple and it is due to the lack of oxygen in the blood. This could be caused by any number of reasons that causes hypoxia. For example, babies can be born with a heart defect that causes mixing of oxygenated and deoxygenated blood, leading to something called “blue baby syndrome”.
Liver dysfunction can present as jaundice, which is yellowing of skin and the white of the eyes due to a build-up of bilirubin.
Some stranger skin changes can be caused by certain chemicals. Carrots contain beta-carotene (which gives carrots their orange colour) and excess consumption can cause carotenosis (or carotenodermia), a yellowing of the skin. Eating too many tomatoes causes a similar condition called lycopenodermia, which presents as reddened skin (lycopene gives tomatoes their red colour). A combination of the two produces a distinctively orange colour. Both conditions are harmless and disappear after reducing the amount of carrots and tomatoes eaten.
Even stranger still is a condition called argyria, which can be caused by exposure to silver, either through medications especially alternative medicine), mining or contamination of the water supply. Silver causes skin to turn a deep blue colour and the pigmentation is irreversible. Similarly, copper can turn skin green and gold can turn skin grey.