Introduction to vitamins and minerals | Biology foundations | High school biology | Khan Academy

We've been told throughout our lives to eat certain foods because they contain vitamins, or sometimes people might say they also contain some minerals that you need.

So the obvious question is, well, what are vitamins and what are these minerals that folks are talking about? Well, the big picture idea is that there are certain things that your body needs, and we'll talk in a second about why your body needs these things. But also, there are things that your body needs that your body does not produce.

The body does not produce—there's a lot of things your body needs that your body is capable of producing. But there are certain things it needs that it cannot produce itself. Now, if these things that they need, that the body needs and it cannot produce, if they are organic—and organic is just a very fancy way of saying if there are compounds that involve carbons in them.

Most molecules in life involve a lot of carbons. That's why they're called organic molecules. There's a whole field of chemistry, organic chemistry, which is studying the chemistry of life. For the most part, if these molecules, if these things that the body needs that it does not produce itself are organic, we call these things vitamins.

Some of the common vitamins that you will hear people talk about are things like vitamin A, vitamin D, vitamin E, vitamin K, and vitamin C. You can further divide these vitamins based on whether they are soluble in fat or not.

So, for example, vitamins A, D, E, and K—and this is by no means an exhaustive list of vitamins—these are fat soluble. What does that mean? Well, to be soluble means you could be dissolved in that thing. So, it can be dissolved in fat, and vitamin C is water-soluble.

Now, the way that the reason why this might be relevant for you, living as an individual trying to keep your health in good shape, is that you do need all of these vitamins. We'll talk in a little bit about why you need them, but fat soluble vitamins—they're actually easier to overdose on because they're soluble in fat.

They can stay in your system a lot longer, while water-soluble vitamins are easier to flush out of your system. Now, with that out of the way, let's think about some of these common foods you might see and some of the vitamins that they are known for. For example, right over here, you have carrots.

You might have had people tell you, "Hey, eat carrots! It's good for your eyes." And that is true, but the reason why it's good for your eyes is that carrots contain something known as beta carotene. The carotene part of beta-carotene is not a coincidence—it literally comes from Latin for carrot, and carotenes are these pigment molecules that give the carrots this orange color.

Right over here, beta carotene, once it's consumed by your body, is a precursor for vitamin A, which is essential for your eyes and many, many other things in your body. A precursor is just a very fancy way of saying that if you consume beta carotene, your body can turn it into the vitamin A that it needs.

Oranges are famous for vitamin C, and this isn't an exhaustive list of the things that these foods contain, but this is some of the things that they're most famous for. Vitamin C, as we talked about, is a water-soluble vitamin. It's very valuable for the immune system, and in a situation where you have a severe deficiency of vitamin C, you could get a disease known as scurvy.

Scurvy is not too common anymore, but several hundred years ago, sailors would often get scurvy because they had very limited diets. They did not get fruits and vegetables, and because of that vitamin C deficiency, their collagen, their connective tissue, would break down. So, it was a very horrible and painful disease.

But what if there's something your body needs that it does not produce that is not organic? Well, those are the things that we call minerals. Of course, the term minerals is also used in a geological sense, but if we're talking in terms of biology, that's what we mean.

Most of the typical minerals are really elements that you will see on the periodic table. They will be things like phosphorus— and I'm just going to write their element symbol: phosphorus, calcium, potassium, magnesium, iron. Again, this is not an exhaustive list, but these are all essential for your body.

As we go further in our studies of biology, you will see how phosphorus is useful in molecules like ATP, the energy store. It's even in the backbone of DNA and RNA. We'll see how calcium is useful, not just for your bones but even for things like muscle contractions to send signals down neurons.

You're going to need your potassium and also sodium; magnesium is also important for muscle contraction. Iron, this is in your hemoglobin; it bonds to the oxygen and allows you to transport oxygen in your bloodstream in red blood cells.

So, these are all very valuable, and a lot of these foods that we just talked about that contain vitamins, they'll also contain minerals. For example, not only do carrots contain beta-carotene, they also contain potassium, which we mentioned is essential for things like nerve function.

Things like milk have vitamins like vitamin D, but it also has minerals like calcium, which we talked about is essential for your bones and for muscle function.

So, the big picture here is that vitamins and minerals are both things that your body needs. It does not produce itself, and we're going to see them over and over again in biology. So, keep a lookout for them— the vitamins, as we go further in our study of biology, you're going to see them as coenzymes, things that help facilitate functions of the cell, help facilitate reactions.

And the minerals, you're going to see in everything from the powerhouse of the cell, the backbone of DNA, you're going to see it in muscle contraction and how bones are formed, you're going to see it in hemoglobin, you're going to see it in nerve function.