BELFAST — Murray Carpenter wrote the book on caffeine, so you would think watching him buy his morning cuppa would be an irritating lesson in modern coffee shop lingo.

You know the drill: “I’ll have a double shot espresso made from single-origin beans grown on a misty mountainside in Guatemala, hand-picked by the same family that’s owned the coffee plantation since 1832, coffee cherries dried in the sun, then micro-roasted with the saliva of the black howler monkey.”

Here’s the reality: “Just coffee,” Carpenter says when I ask what he’s having during our visit to his favorite local coffee shop, Bay Wrap.

Ethiopian, with a little cream.

Sure, he could get his daily caffeine fix from chocolate made with 70 percent cacao, or an energy drink like Zombie Blast (an unspecified amount of caffeine pre-loaded into a shotgun shell container), but Carpenter prefers plain old coffee as a caffeine delivery system. “Coffee’s kind of my thing,” he said. “I don’t get real fancy about it, but I like it.”

SAMPLING THE GOODS

Daily habits aside, during his research for “Caffeinated” (Hudson Street Press, $25.95) – an in-depth look at caffeine as a drug and America’s caffeine culture – Carpenter sampled dozens of products that promise to deliver that familiar buzz that gets reporters (and no doubt the rest of you, too) through many a deadline. He spread those products on the table in front of us.

There were energy drinks, of course, like the Zombie Blast, but also caffeine-filled chews, gels, topical spray-ons and something called Jitterbeans, a candy made from 60 percent cacao with an espresso center. (“Caffeine from 6 cups of coffee in one box!”)

Also on the table, naturally, was an 8-ounce bottle of Coca-Cola, which in its early years was marketed as a stimulant. “In 1909, this size Coca-Cola had 80 mg of caffeine, exactly the same size and caffeine concentration as a modern Red Bull,” Carpenter said. “These guys invented the energy drink concept and then walked away from it.”

POWERFUL POWDER

Of all the products on the table, most daunting was the small plastic bag filled with powdered caffeine that came with a bright orange (voluntary) warning label. I picked it up and read: “Warning! Caffeine is highly toxic in large quantities. Improper use may result in death.”

This powdered caffeine is what goes into soft drinks. It’s also sold to body builders and people who want to try making their own energy drinks. It’s cheap and potent – a single soda might have 1/64 of a teaspoon – so it’s not hard to overdose on it, as one Ohio teenager did earlier this summer.

“What you have in your hand is 10 lethal doses, and anyone can buy that on the Internet for $10,” Carpenter said.

After the Ohio teen’s death, the U.S. Food and Drug Administration put out an advisory that warned consumers to avoid powdered caffeine, noting that it is impossible to accurately measure the powder at home and “a single teaspoon of pure caffeine is roughly equivalent to the amount in 25 cups of coffee.”

We live in a time, and in a place, where people obsess about where and how their food is made and what’s in it. Yet how many hipsters walk down the streets of Portland smug in their knowledge of local foods and exactly how their chicken dinner was raised but have no idea where the caffeine in the caffe latte that they drink every day was manufactured? How many people worry about the amount of sugar in soft drinks and how it relates to the obesity epidemic but have no clue how much caffeine they’re consuming from day to day – not only from sodas but other sources as well?

“I do think we really underestimate the role that caffeine plays in our lives,” Carpenter said. “We structure our days around caffeine, and we really don’t understand caffeine that well.”

In his book, Carpenter treats caffeine as a drug and makes a solid argument that it should be better regulated, while at the same time giving the soda makers and some energy drink manufacturers props for voluntarily labeling the amount of caffeine in their products. (Zombie Blast does not have a label. There’s a detailed label online, but it fails to mention caffeine as an ingredient.)

Proper labeling is a start, Carpenter says, but much more work needs to be done on how caffeine affects the body. Should it be marketed to children and other vulnerable populations? What role should the federal government play in the marketing of caffeine? Should there be federal inspections of the overseas pharmaceutical plants where the production of synthetic caffeine has been outsourced? The FDA is grappling with these issues. (The United Kingdom, the European Union and Canada have already drafted requirements for labeling.)

The science of caffeine is mixed, and people metabolize it differently. Women who are on birth control pills, for example, metabolize it more slowly than the rest of us because they’re producing less of the enzyme that metabolizes caffeine. Smokers, on the other hand, metabolize caffeine twice as quickly.

There are also studies that hint that caffeine might be good for you in some ways, perhaps delay the onset of diseases like Parkinson’s and Alzheimer’s. But then there’s the sleeplessness and anxiety, and that nasty caffeine withdrawal that some of us suffer when we get all righteous and try to go cold turkey, which brings on headaches, fatigue, irritability and muscle pain. It takes as little as 100 mg of caffeine a day – that’s three cans of soda, or 5 to 6 ounces of coffee or three bags of tea – to get us hooked enough to bring on uncomfortable withdrawal symptoms.

“We often want to talk about not being dependent on drugs, and yet most Americans are probably, to some degree or another, dependent on caffeine,” Carpenter said. “So it’s an awkward conversation.”

‘COFFEE A RELATIVE NEWCOMER’

The human love affair with caffeine is at least 3,000 years old and can be traced back to a low, swampy region on the Pacific coast called Soconusco, which borders Mexico and Guatemala. Cacao is grown there, and Carpenter traveled there while researching chocolate.

Tea consumption goes back just as far, according to folklore.

“Coffee is a relative newcomer on the scene – maybe 1,500 years of human consumption – and for many of those years it was chewed,” Carpenter said. “It was not dried, roasted, brewed the way we do it now. It was just rolled up and chewed with some kind of animal fat.”

By the time of the American Revolution and the Boston Tea Party, Americans were drinking coffee from Brazil and the Caribbean. During the Civil War, soldiers roasted coffee in their field encampments and mashed it with their rifle butts. By the early 20th century, coffee consumption was climbing rapidly as production and availability increased and marketing improved. Our parents and grandparents, Carpenter said, drank twice as much coffee as we do, despite the modern-day proliferation of Starbucks.

Around 1950, coffee consumption began to decline precipitously, primarily because of the rise of soft drinks, Carpenter said.

“If you look at how soft drink consumption has changed over that same 60-year period,” he said, “we drink five times as much, by volume, soft drinks as we did in 1950 and half as much coffee.”

Those soft drinks provide less caffeine than coffee, Carpenter explained; still caffeine is a huge part of what’s driving soft drink consumption.

CAFFEINE CONTENT MAY VARY

Buy two cups of coffee and it’s likely they’ll contain different amounts of caffeine, explaining why one cup makes your heart race while an identical cup from the same shop a day later may do nothing for you. In “Caffeinated,” Carpenter tells the story of a researcher who visited a Starbucks in Florida on six consecutive days and each time ordered exactly the same thing: a 16-ounce cup of Breakfast Blend.

The researcher measured 260 mg of caffeine in the least caffeinated cup, while the most caffeinated cup clocked in at 564 mg. The differences are due to variables in growing conditions that can affect caffeine levels in coffee plants. (Brewing strength also plays a role, but in coffee shops brewing is presumably standardized.)

Soda and energy drink manufacturers use powdered caffeine, so presumably each bottle has the same amount of caffeine – although you can’t know for sure unless there’s a label.

Carpenter thinks that dealing with the labeling issue will be fairly easy. What’s more difficult, he said, is figuring out what else might be going into that bitter white powder that gives your soft drink its subtle kick. America imports 15 million pounds of powdered caffeine every year, and most of that gets blended into soft drinks.

According to Carpenter’s book, up until the 1950s powdered caffeine was made by extracting it from coffee, tea, guarana or kola nuts. This is known as “natural caffeine.” Much of what is used today is synthesized in laboratories and known as synthetic caffeine. (Can you sense a future marketing campaign?)

MANUFACTURERS RARELY INSPECTED

Carpenter explains that today most synthesized caffeine is manufactured in pharmaceutical plants in China, Germany and India. Many of these plants, he says, are rarely inspected. For the book, Carpenter traveled to China and tried to get a tour of a plant, but he was not allowed inside. He asked permission in other countries, but no one would let him see the process firsthand.

Carpenter also tried to talk with executives at both Coca-Cola and Starbucks about the sales and marketing of their caffeinated products, but “in both cases, neither of them would have the conversation, period.”

“This is one of the conversations I would have loved to have with Coca-Cola: Why do they formulate Diet Coke for 30 percent more caffeine than regular Coke? I have no idea.”

I mention to Carpenter that on a long drive home recently, after a very long day, I stopped at a gas station to stretch my legs and grab a coffee. On impulse, I bought a Starbucks Doubleshot Espresso drink instead, and it did the trick: within minutes, I was much more alert and ready to continue my journey. I noticed that the nutrition facts label listed 125 mg of caffeine among the ingredients, but all I focused on at the cash register was the language touting the amount of B vitamins. I gave those B vitamins partial credit for slapping me awake, until Carpenter pulled me up short. The B vitamins don’t do anything, he said.

“If you’re vitamin-deprived or something, maybe that’s going to help you,” he said. “But a lot of that is smoke and mirrors. You know, 5-Hour Energy, they advertise with B vitamins, with amino acids and just four calories. They talk about everything in their advertising except the one thing that does give it stimulant value. And that’s because, if you’re just talking about caffeine, they have to differentiate themselves in the marketplace. They get $3 for one of these. If you were getting the equivalent caffeine in, say, a Vivarin pill, it would cost you 19 cents.”

Carpenter himself is never tempted to pick up such drinks. “Every once in a while, when I’m cycling, I’ll drink a Mountain Dew or something because it’s cold and it feels good,” he said. “I really tend to stick to coffee. I like a medium roast coffee brewed strong and a little cream. That tends to be my habit. Every once in a while I’ll have tea.”

Since writing “Caffeinated,” and upon the advice of one of the researchers he interviewed, Carpenter has cut his coffee consumption by about 25 percent. Now he typically drinks three or four 6- to 8-ounce cups of coffee a day, and never in the late afternoon, so the caffeine won’t disrupt his sleep.

Maybe we should all take our own inventory.