There might be more of the periodic  table inside of you than you think.

There also might be more of the  periodic table inside of you that actually does something to  keep you alive…than you think. And to unpack that concept, we’re  going to pull a Magic School bus and shrink down to microscopic size  to understand how the body works.

Across the breathtaking savannahs  of hemoglobin and beautiful beaches of thyroid hormones, we will find massive  herds of carbon and flocks of hydrogen. And if we’re very quiet, and look very closely, we’ll also see some of the rarer elements  that are just as vital for our health. [♪ INTRO] Of the 118 elements on the periodic table, about 90 of those occur naturally on Earth. And just six get most of the credit  for keeping living things alive.

Together, we call them

CHNOPS: Carbon, hydrogen, nitrogen,  oxygen, phosphorus, and sulfur. And each of these elements exist  naturally as individual or pairs of atoms, but they’re more useful to  us when they mix and match into molecules we know and love. From the relatively simple water,  to the rather complicated DNA. We’re mostly made of water, so  if you counted up your atoms, most of them would be hydrogen.

If you measured by mass, the  majority would be oxygen. But if we dive deeper, beyond the sea of CHNOPS, we can celebrate the other atoms  that keep this ecosystem ticking. First, if you look through  that synapse over there…Yes!

It’s a gaggle of charged atoms,  or ions, that are totally vital. Calcium, sodium, potassium,  magnesium, and chlorine are not as famous as the CHNOPS collective,  but they’re not exactly rare, either. And they have a lot of jobs around the body, like keeping your neurons firing, cells  properly hydrated, and bones strong.

All together, these 11 elements make  up more than 99.9 percent of you. But that other 0.1% contains something  like 40 to 50 other elements. These are called the trace elements.

We’re talking iron, iodine, zinc,  silicon, even some lead and uranium. Because if it’s in the environment, it  can get into you when you eat, drink, or breathe, even if it’s just for a little while. But figuring out which of these elements  are bioessential, or necessary for the body to stay healthy, is a topic of  ongoing debate in nutrition science.

There are even different definitions of  what qualifies as bioessential at all. Some experts say that if an organism can’t  grow or survive without a given element, and it’s involved in the way the body, like,  builds up or breaks down molecules, then it’s essential. Meanwhile, others are more  specific and require that, one, it needs to be present in human tissues; two, that its absence causes harm; and three, that reintroducing  the element can stop the damage.

Depending on who’s counting, there are  about 20 to 25 bioessential elements. And after you account for the main 11, that leaves us with about a dozen  bioessential trace elements. And to spot them on this  play-pretend safari of ours, we’ll begin at the local watering hole.

Because just like every creature needs  to venture out for something to drink, every nutrient we consume gets  around via our local waterways… That is, our bloodstream. And the bloodstream is where we’ll find what might be the most familiar  bioessential trace element. At any given time, most of us have  about 5 grams of iron inside of us.

But about 70 to 80 percent of all those  iron atoms are found in one specific place. Look! Right over there!

It’s a red blood cell! But more specifically, it’s the  hemoglobin inside the red blood cell. So, hemoglobin is a protein.

A large, complicated molecule  that has a very precise structure so that it can do its job in the human body. In hemoglobin’s case, that includes ferrying  oxygen molecules around the bloodstream. And it’s the iron atoms that the oxygens  get proverbially stuck to for their journey.

Watch, now, as the dutiful hemoglobin  iron passes its precious oxygen cargo to the iron in an eager myoglobin  protein in the muscle tissue. And…incredible! It also picks up carbon dioxide, a  waste product from that muscle cell, and carries that back to the lungs to exhale.

Just look at hemoglobin go! In total, our bodies use iron in  more than 500 different proteins, so there’s even more it can do. We just don’t have time to cover them all.

And we’ve known for a long time that  not having enough iron feels terrible. Fatigue, dizziness, and shortness of  breath are all symptoms of anemia, and people have been treating it with  iron supplements since the 1600s. But iron is far from the only  metal in a healthy bloodstream.

If you look just a little  bit to the left, over there, you’ll catch a glimpse of another  bioessential trace element: copper. Most of the copper in your blood is carried around in a  molecule called ceruloplasmin. It’s made in the liver, and once it makes  it to your blood, those copper atoms can get added to a variety of other proteins that  do a bunch of other jobs around the body.

For example, you can’t produce  hemoglobin without copper there to help. Isn’t that iron-ic? No Alanis, that’s not what ironic means… We’ve been over this… Copper helps with everything from bone strength, to the production of melanin  and collagen in the skin, to maintaining the myelin sheath outside of a  neuron that helps the signal travel quickly.

So a copper deficiency looks very  similar to an iron deficiency, but it also comes with nerve problems. That said, you’re probably eating more  than enough copper without even trying. It’s present in foods like meat,  shellfish, mushrooms, and nuts.

And unless you have a rare, inherited  condition where copper builds up in your body, you don’t need to worry about how  much copper you’re eating each day. Speaking of which, that brings us  to our next destination: the gut. It’s absolutely teeming with  elements, including cobalt.

No, not the blue stuff. Don’t eat that. That form of cobalt is toxic.

So  is the red stuff while we’re at it. Instead, we get our daily dose of  healthy cobalt atoms from them being tucked inside an unassuming group  of vitamins called cobalamins. You’ve probably heard one of  them go by the name vitamin B12.

And luckily, our lovely host of the safari just ate a vitamin B12-rich meal of… sardines, salmon, peanuts, butter, and molasses. Which is... definitely a choice. Like copper, cobalamins play a  supporting role for certain proteins, including the ones that make DNA, red blood cells, fatty acids, and the building  blocks of other proteins.

It’s also important for nerve and brain function. But if we need more B12, we  actually can’t make it ourselves. We have to get it from our  diet or from supplements.

The good news is, we don’t need very much cobalt: just only 80 to 300 micrograms of B12  are present in the body at a time, and the recommended daily intake  of cobalt is about 6 micrograms. Which makes this a rare sighting. Fantastic!

And as we head from the stomach  into the small intestine… Look over there! Do my eyes deceive me? It’s molybdenum!

Which some of you may have  forgotten is even an element at all. Maybe that’s because molybdenum is only present in four proteins in the human body. But now, you might be thinking, out of  thousands of proteins in the human body, how “bioessential” can these four really be?

Well, molybdenum proteins help  break down toxins and waste. And people whose bodies can’t make these proteins can suffer from severe seizures  and usually die in infancy. And like other bioessential trace minerals, the importance of molybdenum  goes beyond the human body.

Scientists say the genetic instructions  to create these molybdenum proteins is “highly conserved”, which means that it’s  similar or the same across all living things, and it evolved way back in the history of life. During the early Jurassic Period, there  was a drop in ocean molybdenum levels that may have helped cause  a global extinction event! Now, I think that’s all of the bioessential  elements we’re likely to see today.

We’ll have to look out for iodine, zinc,  fluorine, boron, and all the rest next time. But what about the bio-maybe elements, the ones hiding in the shadows,  waiting for recognition? For that, let’s take a quick detour toward  the spine, and check out some silicon atoms vibing in the discs  between this person’s vertebrae.

Scientists used to think of silicon as  inessential in the human body, and some still do. But there’s evidence that suggests it may  help prevent the build-up of aluminum. Oh right, aluminum.

That’s another element in the human body. Just one that isn’t bioessential. In fact, some studies have found a  link between high levels of aluminum and Alzheimer’s disease, so if silicon  reduces the build-up of aluminum, it might be protective.

However, aluminum’s link to Alzheimer’s  disease is still being debated, just like silicon’s… like, essential-ness. And you shouldn’t worry about  everyday sources of aluminum, like soda cans and cooking utensils. But besides that potential benefit,  having low silicon is associated with having low levels of other elements  that are definitely essential.

So some experts argue that this means  it’s plausible silicon is also essential. And research has tried to show  silicon’s importance to bone health, but most studies on its nutritional value were performed in small animals so don’t really, necessarily apply to humans. So the jury’s still out on whether  silicon will join the ranks of recognized, bioessential elements.

Maybe it will have the opposite fate of chromium. Which was once thought to be  bioessential, but has since been demoted. It’s now considered to be  pharmacologically active, which is like the nutrition science equivalent of  re-categorizing Pluto as a dwarf planet.

Having chromium in your body  might have some positive effect, but going without it won’t kill you. So what changed? In the 1970s, a lot of nutrition science  focused on altering what lab rats eat.

For example, when researchers put  rats on a diet of torula yeast, the rats developed liver disease  and impaired glucose tolerance. Adding selenium into their  diet fixed the liver disease, qualifying it as an essential element. And to fix the rats’ impaired glucose tolerance, the researchers turned to brewer’s  yeast and pork kidney powder.

Both of which were high in chromium, so chromium also got classified as bioessential. But in addition to the whole  rats-aren’t-people problem, those early experiments  don’t meet modern standards. For one thing, the scientists never  measured the baseline chromium in a normal rat diet or the torula yeast diet.

So how could they judge the effects of a  low-chromium or high-chromium scenario? And unlike the other elements  we’ve talked about so far, chromium isn't present in any human proteins. It might have a role in controlling blood  sugar and cholesterol levels in rats, but evidence in humans is inconclusive.

But that hasn’t stopped companies from  selling chromium supplements and making claims about how they’ll help you  with weight loss and muscle-building… all while conveniently leaving out the  risk of them damaging your DNA. Nutrition research has come  a long way since the 1990s, when chromium supplements were a fad  and researchers were investigating the nutritional role of lead  and arsenic in low levels. Because yeah, toxic elements exist in nature, so they’re going to get into  your body just by you living.

But spoiler alert: as far as the EPA is concerned, the healthy amount of lead and  arsenic in your diet is… Zero. They’re definitely in you, already. But please don’t go licking  lead pipes or industrial waste.

And most of the essential elements are only useful when they’re embedded in specific molecules. So don’t go adding electronics, and sand, and pennies to your diet either. Because leafy greens and legumes  will do the job a lot better.

You may not be able to get the  entire periodic table inside of you. But believe me, you don’t want to. That’s the kind of life lesson we  wouldn’t be able to get out to the masses without our incredible Patreon patrons.

If you support SciShow over  there, thank you so much! And if you don’t, you can still support us anyway. By liking and commenting on this video, and subscribing to our channel!

Thanks for watching! [♪ OUTRO]