Caffeine Basics: Online Book

Chapters, presented in sequential posts, cover how caffeine works and caffeine's effects on different people. Coffee, tea, chocolate, energy drinks, soda, yerba mate, guarana, and other sources are profiled, with caffeine amounts in each. Topics include pros and cons of caffeine, mental and physical effects. how long caffeine lasts in the body, health, safety, women, children, teens, research and recommendations.

Caffeine in the Toolbox

January 6, 2013 By Kate Heyhoe

Is caffeine a tool for modern humans?

Imagine you’re at the beach. You slide on your sunglasses and spread a towel out on the sand. The sun beats down. Your skin feels hot, so you apply sunscreen. At first you enjoy the sun but as the afternoon wears on, you flee, back to the car and eventually home to an air-conditioned house. As you change clothes, you admire your tan.

You’ve just demonstrated the remarkable human ability to adapt, both biologically and by inventing things that change our surrounding conditions.

Human adaptation is key to our success. Our skin releases melanin to protect against the sun’s rays. We build shelters to keep out wind, rain, and varmints. Our machines change the temperature of the air. Our ability to cope with the variability of our environment is our biggest advantage. And somehow these things, these adaptations, just flow together over time: we’re not always aware of how we come to cope. We just do.

Is Caffeine an Adaptational Tool?

In so many ways, caffeine makes humans more adaptable. With caffeine, we can avoid sleep. Day can be night, and night can be day. We can ward off hunger and fatigue. We’re more social and exchange ideas. We solve problems, and make things all day long. And when we feel pain, caffeine stops the hurt and keeps us going.

Why do we include caffeine in our diet? It doesn’t provide calories, fat, or protein. It does stimulate neurochemicals that change how we interact with our environment. It’s a source of antioxidants, and it’s delivered in natural substances that contain even more antioxidants. Perhaps we choose caffeine because in some ways, it helps us more than it harms us.

Caffeine’s effects may be making more of a long-term impact than we can easily see. But the fact that most people experience caffeine on a regular, daily basis suggests we may be operating differently, in some big-picture way, from times when caffeine was not widely consumed.

Caffeine can be a powerful tool in the human toolbox. But it comes without a manual. We’re still learning how it works. Fortunately, new tools like MRI scanners and human genome mapping are helping us figure it out. But many of caffeine’s mechanisms – the nuts and bolts of how it works – remain unclear.

Caffeine’s Effects: Good or Bad?

If you’re tempted to lump caffeine into mutually exclusive “good” or “bad” categories, don’t. Caffeine won’t fit. Current research finds evidence that caffeine has benefits, is safe in low to moderate doses, yet it can also be risky for some people. The FDA puts almost no restrictions on its use, but the medical community is more cautious when children, teens, pregnant women, and people with compromising health conditions are involved.

Despite years of research, caffeine remains somewhat mysterious, yet promising.

Caffeine is a drug, but largely an unregulated one. It can be a safe way to increase alertness, reduce fatigue, elevate mood, and improve sports performance. As delivery vehicles, coffee, tea chocolate and other botanicals contain beneficial antioxidants, and may prevent some cancers. Caffeine may also prevent some cancers, lower the risk of diabetes and Parkinson’s disease, and reduce the effects of cognitive aging.

Caffeine probably won’t make you smarter. But it does appear to boost our brains in happy, productive ways. A large number of studies indicate caffeine can help you work faster, increase focus, aid concentration, reduce attention lapses, and benefit recall. How and when you choose to use caffeine may give you an edge.

How much caffeine gives you the best boost? Click to the…next section

Caffeine Basics: Table of Contents

Low or High Doses: Caffeine’s Biphasic Buzz

January 6, 2013 By Kate Heyhoe

Caffeine is safe in low doses, but high doses are risky

Caffeine is biphasic – meaning it delivers significantly different effects when taken at low doses than at high ones.

We see this in research studies, when subjects are given small or large amounts of caffeine. But you and I can also feel the difference.

The more caffeine you ingest doesn’t mean the better the buzz. In fact, caffeine’s most popular effects – feeling good, awake, and alert – happen at low to moderate doses (100-300 mg, or one to three cups of coffee, depending on the person).

At higher doses, caffeine intoxication sets in: jitters, heart palpitations, anxiety, nausea, increased blood pressure, and such. Feeling good turns to feeling bad.

When products deliver high amounts of caffeine in concentrated doses, it’s easy to ingest too much in a short period. People with heart conditions and young people are especially vulnerable to caffeine’s adverse effects. Some energy drinks, energy shots, caffeine powder, and certain “dietary supplements” are more likely to deliver risky doses of caffeine.

Being Smart About Research Results

More and more, caffeine seems to be good for us in many ways. It’s a promising but still mysterious substance. Research results tend to conclude with the admonition “More research is clearly needed.” Or, “The mechanisms of action that account for these effects are uncertain at this time.”

Research may suggest a correlation between caffeine and an end result, but we aren’t always sure what caffeine does to get to that result.

Correlation doesn’t automatically mean causality either; there may be other factors at play, such as other ingredients in the beverage (like antioxidants), or the genetic types of the subjects. Journalists, and researchers, constantly conflate coffee with caffeine, so it’s often hard to tell which substance is really the active player.

Many of caffeine’s adverse effects reported prior to the 21st century seem to have been disproved, or not substantiated. Faulty methodology, unknowns like the influence of genetics, small sample studies, cigarette smoking, and other factors have pretty much tossed most of the scary warnings about caffeine out the door. Some prudent warnings do remain because we just don’t know enough, like the effects on newborns.

In some studies, the amount of caffeine makes a difference in results; one cup of coffee or 100 mg may be as beneficial as drinking water (i.e., no special therapeutic effect), while others require a hefty four to six cups of coffee or the caffeinated equivalent, which is enough to throttle many drinkers into the jitter zone. To make things even more confusing, caffeine in coffee may not yield the same results as caffeine in tea, sodas or energy drinks, or these other beverages may not have been tested as rigorously as coffee.

Finally, potential conflicts of interest can influence the results or their interpretation. Trade associations for coffee, sodas and energy drinks, tea, and chocolate actively fund scientific research studies. They may have no influence on the results, but it’s good to know who’s paying the bills, especially when results are conflicting or suddenly groundbreaking.

Next up: It’s all about you! How your uniqueness determines caffeine’s effects…Head over to Chapter 7

Caffeine Basics: Table of Contents

7. Uniquely You: Set Point, Genes, and Half-Life

January 7, 2013 By Kate Heyhoe

One size does not fit all – especially with caffeine.

This chapter helps explain why some people can drink five cups of coffee a day, and others top off at one. And why coffee is habit-forming for some people, but others have no problem quitting their morning joe.

We’re not always sure how caffeine works, but one thing is clear: all sorts of variables impact how each individual metabolizes caffeine, and even these change throughout a lifetime.

Early caffeine studies often treated subjects the same, whether they were men or women, smokers, or old or young. But over the past decade, scientific research has been more rigorous, aided by tools like the human genome project, MRIs, and other advances. Some of this newfound knowledge explains the discrepancies in early research results, and at the same time, reinforces the need for more research.

Want to know why your caffeine experience is unique to you? Jump into the topics of tolerance, genetics, and caffeine’s half-life, as explained in the next three sections…

Caffeine Basics: Table of Contents

Your Habit: Set Point, Tolerance, Withdrawal

January 7, 2013 By Kate Heyhoe

When is caffeine too much of a good thing? The body knows. In most instances, we self-regulate our consumption before serious adverse reactions occur. Our bodies tell us how much we can handle, and we learn to stay within that limit. But over time, we become less sensitive to caffeine’s effects, so we gradually increase consumption, to a point. This response is known as tolerance – and it varies from person to person. (Tolerance happens with alcohol and other drugs too, not just caffeine.)

Your Daily Norm: The Self-Regulating Set Point

Think back to when you first started drinking coffee or tea, or even Coke or Pepsi. You probably started with a small amount of caffeine, say one cup, and gradually drank more until you found a daily “norm,” which may be two, three, or four cups, for instance. You may have even tried more, but scaled back to fewer cups. However much you consume, your daily norm is a measure of your set point – a level of preferred stimulation.

Leveling Off: How Tolerance Works

The brain likes balance. It’s equipped with mechanisms to keep neural activity steady. Caffeine revs up neural activity, so the brain attempts to dampen this frenzy.

Like a commander in battle, General Brain sends in neurochemical soldiers to hold down the fort. The result: you get less of a kick from caffeine. So you fight back with more caffeine, and up your consumption – until the point when General Brain and your caffeine habit reach detente. This balance becomes your set point.

In other words, when a drug’s effects are felt over long periods of time, our adaptive brain adjusts to its presence, and considers the effects to be part of normal brain function. When the drug is absent, you experience cravings. This is true of caffeine, amphetamines, nicotine, and even sugar.

Adapting to Your Personal Level of Caffeine

Think of your set point as your personal adaptation to caffeine. Your set point adjusts as your tolerance level changes. As mentioned, this is true of caffeine and other stimulants, like nicotine and alcohol, and even sugar. Some glucose, or dietary sugar, is essential to normal brain functioning. When the customary balance of sugar in the brain is out of sync, this can also create cravings.

So the absence of caffeine creates cravings in habitual users. And if your habit is to always take caffeine with sugar, your brain expects and craves both the caffeine and the sugar. A daily Frappucino may deliver a double-whammy of reward – and a double-edged craving if withheld. Does this sound familiar?

One school of thought suggests brain boost is really just a result of withdrawal. That is, a caffeine-dependent brain heads into withdrawal between doses (like overnight), and the next hit of caffeine merely jumps our brains back into balance.

There may be some truth to this theory, but it doesn’t explain why both one-time and habitual users experience the same caffeine boosts, at least for certain types of behavior.

For instance, caffeine’s enhancing effects on memory, reaction time, reasoning, mood, and attention span don’t appear to diminish with tolerance (or not severely). Energy-producing or ergogenic actions, like athletics, also happen with just a single one dose. Runners still get the same performance boost whether they’re habitual caffeine users or not.

Caffeine Withdrawal: Three Symptoms in 24 Hours

According to the American Psychiatric Association, caffeine withdrawal syndrome is diagnosed when three or more of these symptoms occur within 24 hours after stopping or reducing prolonged daily caffeine use:

headache
marked fatigue or drowsiness
dysphoric mood, depressed mood, or irritability
difficulty concentrating
flu-like symptoms, nausea, vomiting, or muscle pain/stiffness

Additionally, these symptoms must cause clinically significant distress or impairment in social, occupational, or other important areas of functioning. And, the symptoms are not associated with the direct physiological effects of another medical condition (e.g., migraine, viral illness) and are not better accounted for by another mental disorder.

To avoid these symptoms, experts say to taper off gradually over a few days to a week.

Withdrawal Syndrome and Resetting Your Set Point

If you notice you’re not getting the same kick from caffeine, try resetting your set point by weaning yourself off caffeine for a while. Let the brain and body revert to their natural caffeine-free state.

But if you are addicted and quit abruptly, you may feel symptoms of withdrawal – a classic indicator of physical dependence. Headaches top the list, along with fatigue, sleepiness, brain fog, bad moods, concentration difficulty, depression, flu-like symptoms, and all out crankiness. (Painkillers like Excedrin frequently contain caffeine, so taking them to ease a withdrawal headache is like downing a “hair of the dog” cocktail for a hangover.)

Withdrawal symptoms are why many people never succeed at quitting caffeine. They can’t get past the first 24 hours without ill effects, so they return to their habit. But with caffeine, withdrawal symptoms are minor and best overcome by tapering down on consumption.

Caffeine Intervention: My Personal Reset Plan

I practice a weekly plan to reset my caffeine tolerance level. On weekdays, I drink one cup of coffee, or 100 mg of caffeine (I’m a slow metabolizer, so this is my max). But on Sunday mornings, I switch to a cup of tea, about 25 mg of caffeine. Sometimes I go wild and have two cups of tea, but that’s still half of my normal caffeine regimen. Come Monday mornings, my usual coffee dose seems to have more punch to it. Who would have thought I’d enjoy Mondays all the more? Maybe it’s all in my head, but compared to non-reset weeks, I feel perkier, happier, and rarin’ to go. [Note: This strategy may not work for everyone, and it’s not intended as medical or health advice.]

Coming up: Caffeine’s half-life, or “How long does caffeine stay in my body?”…

Caffeine Basics: Table of Contents

Caffeine’s Complicated Half-Life

January 7, 2013 By Kate Heyhoe

Caffeine’s half-life is longer than cocaine’s

In the 1983 film The Big Chill, actress Glenn Close snorts cocaine, something she hasn’t done in decades. In the following scene, she’s sitting up in bed, fidgeting, rambling, and fully awake, while her husband sleeps soundly next to her. The next morning, he’s peppy and ready for a run, while she’s a wrung out rag of exhaustion.

Caffeine as a drug is a far cry from cocaine. But the two substances have one thing in common: they block sleep. In minutes, caffeine and cocaine turn on your “awake” switch – but shutting down and dozing off isn’t as quick or easy. It takes hours for both drugs to wear off.

The length of time a drug stays in the body is measured by its half-life; it’s the time it takes for half the substance to be eliminated from the system.

Cocaine’s half-life is short, about 90 minutes. Caffeine’s is about three times longer, but caffeine is a far less potent psychotropic drug. In either case, after the half-life moment is reached, the substance continues to churn in your system with diminishing impact, until completely eliminated.

My Buzz vs. Your Buzz

My sister-in-law DeAnn drinks iced tea all day. She carries a giant thermal cup of it wherever she goes, refilling frequently so the caffeine-well never runs dry. She has no problem falling asleep at night. But my brother John, her husband, practically buzzes on Sanka, which is 97 percent decaffeinated. He nurses a single refrigerated can of Coke throughout the day, taking a few sips now and then. Give him more caffeine than that, and he’s up all night, fidgeting like Glenn Close, after her cocaine blast in The Big Chill.

When my husband and I sit down for coffee, we each drink a cup a day, yet the caffeine churns longer in my body than his. Why? Because of multiple factors: I’m 100 pounds, a woman, and part Asian. He’s 160-pounds, a man, and Caucasian. Other genetic traits also make a difference.

Liver Enzymes Can Be Fickle

The liver metabolizes caffeine, using enzymes to break caffeine down into compounds (which are sent to the kidneys and expelled through urine). One particular enzyme, with the fetching name CYP1A2, metabolizes caffeine, as well as other substances.

When this enzyme is in large supply – and not particularly busy – caffeine gets processed and eliminated swiftly. But when the enzyme has a larger workload and is in demand by caffeine and other substances simultaneously, it gets spread thin (kind of like multi-tasking). As a result, the half-life for caffeine – or the other elements, or both – can last longer.

In other words, other substances can speed up or slow down the processing of caffeine in your body. What can compete with CYP1A2’s breakdown of caffeine? Drugs, including but not limited to antidepressants, cardio drugs like Lidocaine, and acetominophen (Tylenol), oral contraceptives, and plenty of others.

Some substances that help caffeine be more quickly processed and expelled include: tobacco smoke, grilled meats, and broccoli. Substances and conditions that slow down the processing of caffeine (so its effects last longer) include alcohol, pregnancy, liver disease, obesity, and possibly even grapefruit juice.

Half-Life Variables

Weight, body mass, sex, age, race, genes, liver function, concurrent medications, and other factors can influence how fast or slow each individual metabolizes caffeine.

So the half-life of caffeine isn’t a fixed number, and even experts disagree on a standard. In this book, I use 4 hours as the rule-of-thumb, but the half-life of caffeine in a healthy adult may range from 3 to 7.5 hours.

Here are some examples of how caffeine’s half-life can vary:

Asians metabolize caffeine more slowly than Causasians
Smokers metabolize caffeine 50 percent faster than nonsmokers; that is, it stays in their system for a shorter period of time (ever notice that smokers consume more coffee than nonsmokers?)
Alcohol reduces the time it takes to metabolize caffeine; drinkers feel caffeine’s effects longer
Liver disease makes caffeine more difficult to process; the half-life can last 96 hours in persons with severe liver disease
Oral contraceptives double the time it takes to metabolize caffeine; the half-life ranges from 5 to 10 hours
Pregnancy boosts the half-life of caffeine; caffeine’s half-life is 9 to 11 hours in pregnant women.
In infants and young children, the half-life is longer than in adults; caffeine’s half-life in a newborn may last 30 hours or more.
The larger the dose, the longer the half-life: Unlike other drugs, caffeine’s half-life is longer at higher doses. In other words, 600 mg of caffeine stays in the system as much as 3 hours longer that of a typical dose of 100-200 mg, which is around 4 hours in most people.

I’ve got more on women, babies and caffeine later in this book. But first, there’s an exciting insight into caffeine’s half-life, and it has to do with our genetic code.

Up next: The caffeine gene determines if you’re a fast metabolizer of caffeine, and it may predict heart attacks…

Caffeine Basics: Table of Contents