If you’re anything like me,when you were a child,   you were made to eat ancient men and  their pet dinosaurs made out of vitamins.

And they tasted super weird,  but like, in a good way. Do you know what I’m talking about?

Flintstones Vitamins. But what is a vitamin? Is a vitamin actually a specific thing?

Or is it just a category that can include,  like, anything that's kind of good for you? Also, why are there so many Bs? Like, why do you jump from E to K?

Do they have anything in common with each other,   and what makes vitamins so much more special  than all the other things in my food? To sort this all out, we’ve got to go back  more than 100 years to the early 1900s. Because scientists were about to ruin dinner time  for children everywhere by discovering vitamins. [♪ INTRO] In the late 19th century, scientists started to realize that what we eat is just  as important as how much we eat.

They were getting really curious  about the components of food,   specifically why some foods are  more nourishing than others. They knew about protein, fat, and carbs,  which we now call the macronutrients. And they also knew about the  importance of water and salt.

But it was clear that these five basics  weren’t sufficient for good health. There were diseases like scurvy,   where people on long sea voyages would start  losing their teeth and bleeding internally. And dying… And diseases like rickets, where kids’  bones would grow soft, weak, and deformed.

Germ theory was pretty new at that point, but  these diseases didn’t seem to be caused by germs. Before too long, scientists pieced together that  some diseases must have something to do with food. Not just the quantity, but the quality, too.

In 1912, a biochemist, Frederick Gowland  Hopkins published a series of experiments   that showed that when animals were  fed mixtures of pure protein, fat,   carbohydrate, and salt, they did not  just fail to thrive, they could not grow. And yet, when small amounts of milk  were added back into their diet,   their health quickly improved  and they could grow once again. At the same time, also in 1912, a  researcher named Casimir Funk was   looking for the cause of yet another  disease, this one called beriberi.

Like scurvy and rickets, beriberi  didn’t seem to be caused by infection,   but it had pretty serious consequences,  like leg numbness and even heart failure. Funk theorized that something called a “vitamine”, a combination of “vital” and “amine”, was the substance missing from  the food of people sick with beriberi. He named the mysterious chemical “vitamine”  because he thought it was an amine,   which is an organic molecule made out  of carbon, nitrogen, and hydrogen.

It turned out that he was half right. There was something missing from  peoples’ diets, something vital. Something that they could not make on their own  that would cause disease if they were deficient.

But the thing causing beriberi was not an amine. Still, this name stuck around, and as  more vital compounds were discovered,   people started calling them vitamins. He also called them “vitamines”  because he was French. [French Accent] Vitamine.

To this day, we’re still quibbling a bit  about the precise definition of a vitamin,   but there is one very important distinction. To be a vitamin, the compound should be essential,   meaning we need it to live and grow,  but we cannot make it ourselves. It also has to be different  from the macronutrients,   because we already know those  do, like, bunch of other things.

That’s it. That’s what a vitamin is. But as we will see, it’s actually pretty  difficult to find compounds that fit that bill… On the other hand, the way they  got their names is far simpler:   they’re named alphabetically  in order of discovery!

Starting with Vitamin A. Vitamin A was discovered in 1913 by two  scientists: Marguerite Davis and Elmer McCollum. But McCollum, who originally called  the compound “Fat-Soluble-A”,   was accused of scientific misconduct and of  basically stealing other people’s research.

The accusations got so bad that he  left for a different university. Decades later, archivists did find evidence  of data manipulation in McCollum’s notebooks,   so it’s possible that he was doing  some bad science in his career. Despite the drama around one of its discoverers,  Vitamin A was ready for the spotlight!

By the 1920s, it had its name at  the front of the vitamin conga line,   and people were starting to  understand a bit about what it does. It is a fat soluble micronutrient that  comes in a lot of different forms. One of its most common forms is called retinol.

It’s found in high doses in  animal products like liver. And orange vegetables, like carrots,   have beta-carotene which your  body converts into vitamin A. Vitamin A deficiency leads to eye lesions,   which is why you have probably heard  that carrots are good for your eyes.

But too much of a good thing  is definitely possible. We now know that too much Vitamin A can cause  birth defects, which is why eating liver,   which has a high Vitamin A concentration,  is no longer advised during pregnancy. If Vitamin A was the first vitamin discovered,   it stands to reason that  Vitamin B would be the next one.

Except you might be wondering exactly  which Vitamin B we are talking about. And you would not be wrong to wonder. There are loads of B vitamins, all  discovered between the 1920s and 1940s.

There are so many because, at first,   people thought that all the B  vitamins were the same thing. They were all essential nutrients  that could dissolve in water,   and while researchers could tell that  they were slightly different chemically,   they assumed all those water-soluble chemicals  had basically the same function in our bodies. And it is true that they all act as coenzymes.

That is, a substance that binds to  an enzyme to help it start working. Later on, though, we figured out that each  B Vitamin does something a little different,   so we subdivided the Vitamin  B complex into numbers based   on the order of their discovery or isolation. So, let’s run through all of them real quick.

Vitamin B1 is thiamine. Vitamin B1 cures beriberi, and helps  your body make energy from glucose. Vitamin B2 is riboflavin, which  helps with vision and metabolism.

Vitamin B3, is the compound that  Casimir Funk actually discovered. It’s called niacin and it  supports digestion and the skin. So Funk did find a vitamin, it just wasn’t  an amine, and did not cure beriberi!

Vitamin B5 is also called pantothenic acid. It helps your body produce energy. Vitamin B6 is pyridoxine, which  helps with blood oxygenation.

Vitamin B7 is biotin, which  helps your body make fatty acids. Vitamin B9 is folate, or in  synthetic form, folic acid. This one is essential for cell and tissue growth,  so it’s usually taken as a prenatal supplement.

And finally, Vitamin B12 is cyanocobalamin,   an essential nutrient for the  formation of red blood cells. And now you’ve got a new question:  That wasn’t all the numbers, Hank! What happened to Vitamin B4,  and B8, and B10, and B11?

Well, simply put, those vitamins got demoted. These are the Plutos of the  vitamins and you’ve never cared. But if you wanna care about Pluto,  you should also care about Vitamin B4.

B4 turned out to be adenine, a component of DNA   and something our body makes all  the time, so it’s not a vitamin. B8 is inositol, which your body  can use to help process insulin. Your body also produces this  naturally, so it is not a vitamin.

B10, or PABA, is part of the folic acid  molecule, which is already Vitamin B9. And B11 turned out to be salicylic  acid, which is great for skincare   and a precursor to aspirin, but not  exactly essential to our health. Funding, however, is  essential to SciShow’s health.

So we’re going to take a quick break. This SciShow video is supported by Uncommon

Goods: the place to find creative gifts for  everyone you know, including yourself. Uncommon Goods looks for products  that are high-quality, unique,   and often handmade or made in the US. Many are crafted by independent artists and small  businesses, making them truly one of a kind. You can find a glowing plush  anglerfish on their site.

If you have anyone on your list named  Hank, this could be the perfect gift. I’ve heard that literally every Hank likes an anglerfish. This one flips inside out to reveal a blend  of science, silliness, and sea creature charm.

If you want a closer look you’ll have to go to   UncommonGoods.com/SciShow to see what  I mean and get 15% off your anglerfish. So for all your Hanks, and your  friends who have everything,   and your in-laws who are tricky to  shop for, Uncommon Goods is here. Uncommon Goods makes holiday shopping a better  experience than panic-scrolling through old gift   guides, with thousands of one-of-a-kind gifts  for everyone on your list — all in one place.

And with every purchase  you make at Uncommon Goods,   they give back 1 dollar to a  non-profit partner of your choice. They’ve donated more than  $3.1 million to date. There’s no time like the  present to get those presents.

You can cross those names off  your list before the rush. To get 15% off your next gift,  go to UncommonGoods.com/SciShow As their motto says, “Uncommon Goods.  We’re all out of the ordinary.” While some researchers were figuring out all those  B vitamins, others had already moved on to C. Vitamin C was discovered in 1928, and  like the B vitamins, it is water-soluble.

But C is different enough from the  B vitamins to stand on its own. Interestingly, loads of animals can make Vitamin  C, also called ascorbic acid, but we cannot. And that’s really unfortunate for us,  because Vitamin C is one of the building   blocks of collagen, a structural protein that  keeps our bones, skin, and ligaments healthy.

Which is why Vitamin C deficiency leads to scurvy. Scurvy is primarily caused by  a lack of healthy collagen. But Vitamin C also acts as an antioxidant,  protecting your body from harmful free radicals,   helping you absorb iron, and  boosting your immune system.

Although that last point does  come with a bit of controversy. While Vitamin C has been marketed  for decades to fight colds and flu,   results from clinical trials have been mixed... Vitamin C does appear to shorten severe  cold symptoms, so it could help you if   you feel really ill, but it doesn’t  seem to do much for mild symptoms.

But do not take this as an invitation  to down loads and loads of Vitamin C. Taking more than 1,000 to 2,000 mg  of Vitamin C in a day can lead to   kidney stones and gastrointestinal  problems, so, you know…take it easy. Plus your body can’t store up Vitamin C,   which means there’s no point in taking more  of it than you can use in any given day.

So we’ve solved beriberi and  scurvy, but what about rickets? Well, rickets is caused by a deficiency in  the next vitamin on our list, Vitamin D. It was identified between 1900 and 1920.

And like vitamin A and B, it’s actually  a group of molecules, and D2 and D3 are   the ones that are really important for human  health, together referred to as calciferol. Vitamin D helps your body process calcium,  which is important for bone growth. It also supports your immune system  and helps with glucose metabolism.

Now, D is a bit of an odd duck among the vitamins. Remember when we said that vitamins have to be   essential, meaning that we  do not make them ourselves? Well… there’s been a lot of debate about  whether D actually fulfills that criteria.

We do make it, and we do it quite  well when we are exposed to UV light. UVB rays can convert a molecule that naturally  occurs in our bodies into the Vitamin D we need. But in the absence of UV light,  we just won’t make vitamin D.

And since Vitamin D deficiency is real,  and leads to rickets in extreme cases,   scientists have come around to calling  Vitamin D conditionally essential. This means that we can make  it, but we require the right   circumstances to make it in adequate amounts. So in a way, it’s just like the other vitamins:   we need it from our environment, except it  comes from sunlight instead of leafy greens.

It might sound like an easy  prescription—just go outside. But it turns out that getting enough  sun to produce sufficient amounts of   Vitamin D is not always trivial,  especially at high latitudes. All over the world, we’re  spending more time indoors,   so we need to make sure we’re getting enough.

That’s why babies are usually given Vitamin D   supplements from just about  the moment they’re born. Side note here, when we say UV exposure,   we are definitely not telling you  to go out in the sun unprotected. Your body can still make Vitamin D if  your skin is protected by sunscreen!

So please do wear sunscreen when you’re  getting your daily dose of sunlight! Producing a small amount of Vitamin D probably  is not worth getting skin cancer in the long run. Like D, Vitamin E was discovered in 1922.

It’s a group of 8 fat-soluble molecules that  all differ slightly in chemical composition. Four of them are known as tocopherols, and  the other four are known as tocotrienols. But only one of those forms, alpha-tocopherol,   meets your body’s requirements, so when we say  Vitamin E, we are usually referring to that.

People are very rarely deficient in Vitamin E,   so most of us don’t need to do anything  special to keep up our vitamin E levels. One of the things Vitamin E is best known  for, though, is keeping skin and hair healthy. Which explains why it’s found in so  many hygiene and cosmetic products.

Last but not least, we have Vitamin K,  which was discovered in the early 1930s. And, yeah, I know: What happened  to F, and G, and H, and I, and J? Well, remember how we decided that  vitamins have a standard definition?

Those letters just didn’t make the team. Vitamin F turned out to be the  fatty acids omega-3 and omega-6. And while we definitely need  those in our diet, they are fats,   which means that they fall under the  domain of macronutrients, not vitamins.

Vitamin G turned out to be Vitamin B2,  and Vitamin H was actually Vitamin B7. Vitamin I was never assigned for some reason. And Vitamin J turned out to be B2, too. …I mean, Vitamin B2 as well.

So we moved on to K, which is the last  of the vitamins we still recognize today. It is yet another family of fat-soluble molecules:   phylloquinone, or K1, menaquinone, or  K2, and a synthetic K3 called menadione. Vitamin K helps with blood  coagulation and bone mineralization.

It helps activate the proteins  that get blood to clot,   making it extremely important for newborn babies. Babies are born with very low levels of Vitamin  K, so it’s been standard practice for a while   to give them Vitamin K shots after birth to  lower the risk of dangerous internal bleeding. There’s also some evidence that  Vitamin K might help with osteoporosis.

This is still an active area of research,   but it might turn out that Vitamin  K is helpful later in life, as well. And that’s a wrap on the vitamins! We have not added any new vitamins  to the list since about the 1940s.

Instead we’ve been focused on refining  our understanding of the vitamins we have. Discovering vitamins changed our  lives in pretty important ways. Beyond just treating horrible  conditions like scurvy and rickets,   knowing about vitamins meant that we could fortify   food to ensure our populations get  enough of these essential nutrients.

That’s why so many of our foods are  “fortified”, especially milk and cereals. We also know the importance of a balanced   diet that includes plenty of  fresh fruit and vegetables. And in case of deficiencies, we know  exactly how to offer targeted treatments.

While the naming convention  might not always make much sense,   and the definitions might need a bit of updating,   it’s clear we owe a lot to our vitamins and  the many researchers who discovered them. So, everybody: Eat your vegetables! [♪ OUTRO]