Archives for 2013

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

The Caffeine Gene and You

January 7, 2013 By Kate Heyhoe

In the old days, fortune-tellers read tea leaves, coffee grounds or palms to predict the future. Today, genetic testing companies reveal your personal mysteries, with scientific accuracy. They tell you who your child’s other parent is, who your own parents are, whether cancer runs in the family, or if the person who looks just like you on YouTube really is your long lost sibling. Get your genetic data now!

Here’s where things get interesting: There appears to be a big kernel of truth to the idea that your genes dictate how fast you metabolize caffeine. You can actually find out if you’re genetically programmed to crave large or small amounts of caffeine. All it takes is a simple cheek swab, sent to a genetic testing firm. So let’s jump straight to the actual research – which reveals that caffeine lingers longer when certain genes are switched on or off.

Clear as Mud Becomes Crystal Clearer (almost)

Caffeine researchers hit an “aha!” moment in 2010. They discovered that two genes determine whether you metabolize caffeine slowly or quickly. Together, these two genes are responsible for inherited differences in the way people process caffeine. They’re one reason why some people get amped from a single cup of coffee, while others down three cups before noon and another two at dinner, and never once jitter.

It’s in your genes, as the saying goes. Environmental factors, like whether you’re a smoker, still play a role. But genetic markers appear to explain a lot.

The two genes are known as CYP1A2, which has long been associated with caffeine (it produces an enzyme by the same name), and AHR, a gene that regulates the activity of CYP1A2. Researchers sifted through 300,000 genetic markers, before noticing that these two genes were essentially holding hands.

Slow and Fast Metabolizers

Every person has both of these genes, but CYP1A2 comes in two versions (or alleles; in this case differentiated by a single nucleotide). It’s like having a switch that is either turned on or off. This tiny variation makes you either a slow or fast metabolizer of caffeine ¬– it regulates how efficiently your liver breaks down and flushes caffeine from your system.

Slow metabolizers tend to drink less coffee (or other form of caffeine); fast metabolizers fuel up on more caffeine to keep feeling its effects. In one report, fast metabolizers averaged 40 mg more caffeine per day than did slow metabolizers.

In case you’re wondering, these particular caffeine genes don’t just regulate caffeine. They’re actually multi-taskers, and control other compounds, including ones related to certain cancers. (While we’re on the subject, different genes play a role in alcohol and nicotine addiction, too.)

The Caffeine Gene’s Split Personality

If you’re up for more complicated data: CYP1A2 also refers to an enzyme, generated by the gene CYP1A2 (genes are usually differentiated from their enzymes by italics). CYP is an abbreviation for a superfamily of enzymes and their encoding genes, known as cytochrome P450. The numbers and letters that follow CYP indicate the gene family, subfamily, and specific gene. Are your eyes glazing over yet? This may be too much information, but if you see CYP1A2 referenced as a both a gene and an enzyme, you’ll understand why.

Heart Attack Risk: What the Caffeine Gene Shows

One study based on 4,000 coffee drinkers used the CYP1A2 gene to identify slow and fast caffeine metabolizers, and their relationship to heart health. Slow metabolizers showed an increased risk of nonfatal heart attack. Women appeared to be at a slightly higher risk than men, probably because hormonal differences also slow caffeine’s breakdown in women.

For men and women, slow metabolizers showed increasing risk of nonfatal heart attack with increasing coffee consumption. Fast metabolizers, those who drank up to 3 cups a day, actually had a lower risk, as much as 52% lower.

So here’s the takeaway:

If you are a slow metabolizer, then drinking more than a cup of coffee a day may be risky for your heart. But a single cup of coffee seems to have no effect on heart risk, regardless of the genome variants. Moderation and self-regulation appear to be key.

Next Up: Are you addicted to caffeine? Chapter 8 looks at clinical caffeine disorders, including “The Starbucks Defense”…

Caffeine Basics: Table of Contents

8. Caffeine: Addiction, Withdrawal, Disorders

January 8, 2013 By Kate Heyhoe

If quitting caffeine has been on your mind, this is the chapter to read….

Got a caffeine habit? Welcome to the human race.

Ninety percent of the world consumes caffeine every day – as coffee, tea, chocolate, soda or other buzzed-up substance.

In Asia and Russia, tea is drunk from morning to night; and coffee’s hot in Japan and Korea.
In South America, people get their fix from coffee, guarana, or yerba mate (so many choices!).
In Brazil – the world’s main coffee supplier – even toddlers drink coffee at breakfast.
Coca-Cola peps up people of all ages, in all corners of the globe.

Chocolate lovers get a caffeine-fix, too. I don’t just drink caffeine, I devour it: two bites of dark chocolate punctuate my daily lunch.

Read on to find out why caffeine is a socially acceptable, habit-forming – and some say addictive – drug. Caffeine has plenty of benefits, but it’s still a drug that can get out of control. This chapter explains these caffeine-related medical conditions (some of their symptoms may sound very familiar):

Mental health conditions can worsen when combined with caffeine, and a famous legal battle was won using the so-called “Starbucks Defense.” This chapter also covers how much caffeine is safe and when it can be lethal.

But first, the next section asks: Are you addicted to caffeine, or it just a habit?…

Caffeine Basics: Table of Contents

Caffeine: Are You Addicted?

January 8, 2013 By Kate Heyhoe

If you consume caffeine every day, in a regular fashion, you’ve either got a habit or are addicted – pick the term you prefer.

Experts quibble over whether to call caffeine addictive or just habit-forming. The difference is somewhat a matter of semantics, but not entirely.

An addiction suggests self-destructive behavior, one that poses a threat to individuals or society, as in a heroin or cocaine addiction. For most of us, caffeine doesn’t match that type of downward spiral. Caffeine’s generally not emotionally or physically destructive, though it can be in some people, and that’s when experts consider it an addiction.

Caffeine does act like other addictive substances by tripping the reward and pleasure circuits of the brain (which explains a lot about its popularity). It is undeniably habit-forming, but most of us don’t experience adverse effects from typical doses. Caffeine can even have benefits, such as lifting depression and reducing certain cancer risks, or enhancing certain mental and physical tasks.

Whatever you call it, if you’re hooked on caffeine, don’t panic: clinically speaking, caffeine is only mildly addictive or habit-forming. Most people can easily quit caffeine, if they survive the withdrawal stage. Though intense, withdrawal symptoms typically pass in a matter of days.

How has your caffeine consumption changed? If you do have a caffeine habit, chances are you now take in more caffeine than when you first started. That’s normal. It’s known as developing tolerance. When you hit that sweet spot of daily consumption, not too strong or too weak, you’ve found your setpoint, which is covered in Chapter 7.

So if you do have a caffeine jones, relax. You’re in good company. But if you’ve not developed or don’t want a caffeine habit, some experts say there’s no reason to start one.

Caffeine: Deep Addiction or Mild Dependency?

It’s not easy to tell if someone’s on caffeine.

Caffeine’s not like alcohol; it may elevate your mood, but people don’t get giddy or use it to escape from their troubles. Caffeine doesn’t make you slur your words or walk funny.

It’s typically used to sustain or enhance functionality. We trust our lives to people on caffeine: airline pilots, teachers, firefighters, even the President of the United States. In dangerous situations, we might even prefer that these people be on caffeine, to boost their alertness and performance.

Caffeine is also self-regulating, as discussed earlier, which prevents most of us from spiraling into dramatically destructive scenarios. Once our hands start to shake, we turn off the caffeine tap.

True enough. But caffeine does have a real effect on reward circuits of the brain, one that is consistent with addiction. Breaking the caffeine habit includes the same physical and mental withdrawal symptoms that define a substance as addictive. When your hands shake, yet you’re still pouring caffeine, that’s a sign your habit is out of control.

Let’s revisit what caffeine does to our neural wiring: Caffeine stimulates dopamine, a source of feel-good effects. According to some experts, it does so in areas of the brain separate from where cocaine and harder stimulants activate the neural wiring. So, caffeine activates some reward circuits, but it may do so in a manageable way.

Perhaps it’s best to view caffeine as a mildly addictive substance, one that presents benign effects or adverse risks, depending on the user and quantity ingested. And keep in mind that caffeine is biphasic: low to moderate doses create profoundly different effects from those of high doses.

Symptoms of Caffeine Addiction

What are the symptoms of caffeine addiction? As the next section shows, there is a beast known as Caffeine Use Disorder, and you only need three symptoms to qualify…

Caffeine Basics: Table of Contents

Caffeine Addiction Symptoms

January 31, 2013 By Kate Heyhoe

AddictionShip When does caffeine cause someone to lose control? For many of us, caffeine is no more habit-forming than relying on a morning shower to wake up.

But compulsive caffeine consumption – to the point where sleep is disrupted on a regular basis, or hands tremble – suggests a physical and a psychological dependence, perhaps even a mental health disorder.

The word “addiction” is an emotionally charged grenade, packed with social stigma and misconceptions. Many health professionals now use the term disorder, as in “Caffeine Use Disorder”– a condition where sufferers continue to use caffeine, even though it adversely affects them in some way. (It’s also been called caffeinism.)

But Caffeine Use Disorder isn’t fully recognized – yet. When the bible of addiction, The Diagnostic and Statistical Manual of Mental Disorder by the American Psychiatric Association, updated the 2013 edition (DSM-5), it placed Caffeine Use Disorder in the “conditions for further study” category. More scientific studies are needed, said the task force. Because caffeine is so commonly used, and to prevent over-diagnosis, Caffeine Use Disorder needs to have a higher threshold of diagnostic criteria than those used for other abuse substances.

Nevertheless, the proposed definition for Caffeine Use Disorder is illuminating. It identifies 9 symptoms, and says the first three or more are needed to present a diagnosis of Caffeine Use Disorder. Some of us may recognize particular symptoms in ourselves, such as: a strong craving for caffeine; unsuccessful efforts to cut back or stop caffeine use; and tolerance marked by the need for more caffeine to reach the same effect. See if any of these conditions apply to you or someone you know.

Caffeine Use Disorder: 3+ Symptoms

You need at least the first three symptoms (within a 12-month period). Plus, there must be a problematic pattern of caffeine use leading to clinically significant impairment or distress, according to the proposed definition for Caffeine Use Disorder.

1. A persistent desire or unsuccessful efforts to cut down or control caffeine use.

2. Continued caffeine use despite knowledge of having a persistent or recurrent physical or psychological problem that is likely to have been caused or exacerbated by caffeine.

3. Withdrawal, as manifested by either of the following:

a. The characteristic withdrawal syndrome for caffeine.

b. Caffeine (or a closely related substance) is taken to relieve or avoid withdrawal symptoms.

4. Caffeine is often taken in larger amounts or over a longer period than was intended.

5. Recurrent caffeine use resulting in a failure to fulfill major role obligations at work, school, or home (e.g., repeated tardiness or absences from work or school related to caffeine use or withdrawal).

6. Continued caffeine use despite having persistent or recurrent social or interpersonal problems caused by or exacerbated by the effects of caffeine (e.g., arguments with spouse about consequences of use, medical problems, cost).

7. Tolerance as defined by either of the following:

a. A need for markedly increased amounts of caffeine to achieve desired effect.

b. Markedly diminished effect with continued use of the same amount of caffeine.

8. A great deal of time is spent in activities necessary to obtain caffeine, use caffeine, or recover from its effects.

9. Craving or a strong desire or urge to use caffeine.

Having these symptoms is no guarantee you’ve got a caffeine disorder, and this is not intended to be medical advice. But if you think your caffeine habit is disrupting your life, you may want to consult your doctor.

Coming up: Quitting caffeine? Get prepared for some painful withdrawal symptoms…

Caffeine Basics: Table of Contents