Most of us go through life without giving a thought to the foods we eat and the goods we use.

When was the last time you thought about the Cheerios in your bowl, or the toothbrushes in your bathroom, or the gas in your car? It was probably only when you needed more of them.

Almost all of us consume caffeine on a daily basis; statistics show that at least 85% of Americans drink caffeinated beverages each day. For some of us, it just happens to be in something that we’re eating or drinking. But for more of us, it’s because we rely on caffeine to get us going or keep us awake. Many of us are convinced, in fact, that we can’t get out of bed or get to work without it. (Fun fact: that’s an exaggeration.)

But the only time most of us think about caffeine is when we need or want more of it. Don’t believe it? Then here’s a question: where does caffeine come from?

No, we don’t mean “it comes from coffee” or “it comes from tea” or “it comes from Coke.” That’s not where it comes from; those are simply beverages that naturally contain caffeine.

We’re more curious about bigger questions. For example: “why do those drinks contain caffeine, but Sprite doesn’t?” And “if caffeine is natural, how can they get so much of it into 5-Hour Energy?”

We hope you’re curious too.

It’s difficult to discuss where something comes from without knowing what it is.

So let’s talk about insecticides.

Wait – what?

We’re serious. Caffeine is a natural, white organic alkaloid that is found in dozens of plants, almost all of them native to South America, Africa and East Asia. Why is it there? Apparently these plants needed a way to fight off predatory insects, and over time they began producing caffeine for that exact purpose.

Caffeine affects the central nervous systems in insects like mosquitoes, milkweed bugs and mealworms, disturbing their growth and behavior. Don’t believe it? Harvard scientists have found that adding caffeine to pesticides makes them ten times more effective.

The stimulant apparently provides plants with two other benefits as well, preventing nearby plant seeds from germinating (so there’s less competition for fertilization) and encouraging honey bees to do their work.

That’s all interesting, but doesn’t have much impact on your morning cup of coffee.

What’s more important is that caffeine acts as a central nervous system stimulant in humans, not just bugs. It’s not a wives’ tale that coffee, tea or caffeine-loaded energy drinks keep you awake by reducing drowsiness. They really do. They can ease neuromuscular fatigue as well.

However, it’s not all espresso and rainbows, since there are health hazards associated with consuming too much caffeine. In fact, downing a single tablespoon of the pure stimulant, in powered form, can kill you. Things won’t get that serious if you’re simply getting your caffeine the “normal way,” though. Consuming a tablespoon of pure caffeine would be equivalent to drinking about 84 cups of coffee.

The Mayo Clinic says up to 400 milligrams of caffeine daily seems safe for healthy adults. That equals four cups of coffee, ten cokes or two energy shots. Higher levels of caffeine intake can cause the familiar side effects of caffeine that most of us have experienced: jitters, irritability and insomnia. Even more caffeine consumption and you’re at risk for rapid heartbeat, headache and muscle tremors. (Excess caffeine consumed by pregnant women can also cause low birth weight in their babies.)

Caffeine isn’t just found in coffee soda and energy drinks, of course.

Coffee

Coffee beans are best-known for their caffeine content, but not all beans are created equal in this regard. An average Arabica bean contains about two milligrams of the stimulant, compared to nearly three milligrams in each Robusta bean.

The type of the beans used and the strength of the brew determine exactly how much caffeine is in a cup. The average cup of filtered coffee contains about 85 milligrams, it’s 65mg for instant coffee, and there is about 60mg of caffeine in a small espresso shot. Even “decaffeinated coffee” contains about three milligrams of caffeine.

In short, while there are no important nutrients in coffee, it contains bountiful amounts of caffeine.

Tea

There’s caffeine in brewed tea, too – but why? The compound occurs naturally in Camellia sinensis, the tea plant which is the source of black tea, green tea and white tea. Black tea contains the most caffeine because it comes from oxidized tea leaves, but still only about half the amount found in brewed coffee. The longer you steep tea, though, more caffeine will end up in your cup.

Yerba mate, a traditional South American tea made from the Ilex paraguariensis plant, contains caffeine as well. Herbal tea is the exception; the plants from which it’s made contain no caffeine.

Chocolate

There’s caffeine in most types of chocolate, but it’s not enough to wake you up in the morning or keep you awake at night. Cacao beans contain only about five percent of the amount of caffeine in coffee beans; chocolate will add to your daily total caffeine consumption, but the sugar and calories in chocolate are more of a concern than its stimulant effect. To put it another way, you’d have to eat an entire bar of milk chocolate, or a drink a cup of hot chocolate, to get the same amount of caffeine that’s in a cup of decaf coffee.

Dark chocolate contains 2-3 times more caffeine than milk chocolate, and the darker the chocolate, the more caffeine it has. Since white chocolate comes from cocoa butter rather than cocoa beans, there’s no caffeine in white chocolate.

Soft Drinks and Energy Drinks

It’s pretty well-known that Sprite and ginger ale aren’t caffeinated, but Coca-Cola and many other carbonated beverages (mostly the cola-style ones) are. Are they made from a plant that contains caffeine, too?

Not exactly. Once upon a time, kola nut extract was used to produce Coke and similar colas, and as you’ve certainly guessed, kola nuts contain caffeine. The extract hasn’t been used for some time, though. (No one’s exactly sure when it was removed, since beverage companies closely guard their ingredient formulas. But it was a long time ago.)

Then where does the caffeine come from? Actually, it’s an added ingredient in soda – supposedly there to provide added taste, although at least one study has shown that it doesn’t do that at all. When the Food and Drug Administration (FDA) proposed a rule banning caffeine in soda 40 years ago, the soft drink industry insisted that caffeine was a crucial additive. They claimed that the bitterness of caffeine was needed to balance the soda’s sweetness. And it’s still there today.

At one point, caffeine for use in soda was extracted from heated coffee beans. In fact, the huge agrochemical company Monsanto got its start as one of the companies supplying Coca-Cola with caffeine. Things haven’t worked that way for a while, though.

Both Monsanto and Pfizer started producing synthetic caffeine in the mid-20th century, through a process that uses ammonia, chloroacetic acid and methyl chloride. Synthetic caffeine has been used in soda ever since, although most caffeine production has been done in China for the last quarter-century. 

If that’s surprising to you, it’s because food and beverage manufacturers aren’t required to identify the caffeine in their products as natural or artificial. There’s also virtually no supervision of synthetic caffeine production – so it’s simply a matter of crossing your fingers (or not thinking about it) and downing that can of Coke to get a jolt of caffeine.

Synthetic caffeine is the primary stimulant ingredient in energy drinks, although some also contain the extract of guarana berries, which do contain natural caffeine. (Synthetic caffeine is also added to many over-the-counter headache medications, because it’s been found to amplify the meds’ effectiveness.)

Natural and synthetic caffeine are chemically identical, but the body absorbs the synthetic version faster. That means the energy boost comes more quickly – as does the crash that follows.

Caffeinated drinks like Coke and Pepsi have caffeine levels about half that of coffee, about 35-40 milligrams of caffeine per can, which is why a Coke doesn’t get you as “juiced” as coffee. Mountain Dew contains about 55mg, and energy drinks like Red Bull come in well over 100mg of caffeine. A 5-Hour Energy Shot has twice as much as a Red Bull, and there are drinks like Spike Hardcore Energy that top out at about 350mg  of caffeine per can.

Other Natural Sources of Caffeine

Two other plants that naturally contain caffeine are sometimes used for their stimulant effects.

Guayusa tea is made from, naturally, the guayusa plant. It’s primarily drunk in South America. The leaves are also processed and sold as a powder and extract in America because of its additional health benefits. Guayusa is added to some energy drinks as well. 

The other plant, yaupon holly, is native to America. Native Americans have traditionally used it to make yaupon tea, but the beverage hasn’t caught on to any great extent.