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Caffeine: Friend or Foe?

02 March 2022

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What do you really know about caffeine? Maybe it’s simply that your mornings are a little brighter after your cup of coffee or that caffeine in the afternoon keeps you up at night. 

Caffeine is a plant alkaloid. In its pure form, caffeine is a bitter, white powder. In the body, its half-life (the time required for the concentration of a substance in the body to decrease by half) varies by individual. Generally the half-life of caffeine in healthy individuals’ plasma is about five hours. Caffeine’s elimination half-life, which means the time it takes for half the dose to vacate the body entirely, can range from 1.5 to 9.5 hours. Simply put, caffeine affects people very differently. Some folks can drink coffee (or soda, iced tea, energy drinks etc) all day long and sleep like a baby. Others can accidentally drink one cup of caffeinated coffee at 6AM and feel wired until the next day.

Ever wonder what the most widely-consumed drug in Western society is? The National Institutes of Health has one word to say about that: caffeine. Some 85 percent of the population drinks at least one caffeinated beverage per day, according to the National Consumers League. Average intake of caffeine ranges from 110 milligrams per day (mg/day) for women ages 19-30 to 260 mg/day for men ages 51-70. Children consume less, with an average of 5-32 mg/day. Teens are slightly higher, at 63-80 mg/day.

How much caffeine is too much?

Well, you can actually overdose (fatally) on caffeine. The estimated fatal acute oral dose of caffeine is calculated at 150-200mg/kg body weight. That’s ten to 14 grams of caffeine. After ingestion of ten grams, convulsions and vomiting can occur. Ingesting just one gram can cause extreme side effects ranging from nervousness, irritability and restlessness to delirium, neuromuscular tremors, convulsions and vomiting.  

An eight-ounce cup of coffee contains about 95 mg of caffeine. A single shot of espresso contains about 65 mg. One can of Red Bull energy drink packs 111 mg, and a can of Diet Coke contains 46 mg. Rock Star and Monster energy drinks contain 160 mg per can. Specialty coffee drinks can pack much more caffeine than a plain old cup of Joe. A 20-ounce Starbucks drip coffee contains 415 mg; the same size Dunkin’ coffee with a turbo shot packs 395 mg; a 12-ounce cup of Death Wish brand coffee contains an astounding 651 mg.

Some negative effects of caffeine include:

Caffeine withdrawal. Suddenly halting your usual relationship with caffeine can cause your body to go through withdrawal. The first thing you’ll probably notice is a shrieking headache. This is because caffeine narrows or constricts the blood vessels in your brain. Without caffeine, the vessels widen back out, which triggers a sharp headache. If you banish caffeine, expect two to nine days of headaches, with the most intensity on days one and two. You may also notice rebound fatigue. Caffeine artificially inflates your energy level, so when it’s removed from your system you feel extra tired. 

Increased production of urine. Because caffeine is a diuretic, it increases your body’s urine production, sending you to the bathroom more often, and also makes it feel like you have the urge to urinate with greater frequency. Caffeine is also thought to irritate the tissues in your bladder, causing involuntary contractions and a sudden, strong desire to urinate that cannot be ignored, AKA urge incontinence.

Gastrointestinal disturbances. Caffeine’s stimulant effect can ramp up gut motility, which is the contraction of muscles that move the contents of your gastrointestinal tract through your system. This overstimulation can cause diarrhea and/or loose stools which in turn can cause dehydration. 

Heart palpitations. Bursts of adrenaline can cause isolated heart palpitations or surges of faster heartbeats. Things that can cause them include strong emotions like fear or excitement. Consuming a stimulant, like caffeine, can also cause them.

High blood pressure/increased heart rate. Caffeine, a stimulant, affects the central nervous system, and can increase heart rate. Caffeine affects people very differently – some will begin to feel symptoms, such as elevated heart rate, within 15 minutes of ingestion. Caffeine causes your adrenal glands to release more adrenaline, which causes blood pressure to increase.

Mood. A little caffeine can boost your mood and alertness temporarily but too much caffeine can increase feelings of anxiety. Anxiety makes us feel wound up, restless and edgy. It may be hard to settle on a task or train of thought. Too much caffeine can also make us irritable.

Fight or flight. Drinking caffeine causes a release of adrenaline, the hormone responsible for our ‘fight or flight’ survival response. This response, or mechanism, is designed to help you survive imminent danger like being chased by a moose. It allows you to ‘override’ stepwise thought and act forcefully, which isn’t so great when you’re at work, perhaps responding to a colleague who has annoyed you. When too much caffeine flows through your system,  

Sleep patterns. Say you didn’t sleep well Tuesday night, so Wednesday morning you drank more coffee than usual and, because you needed to be on your game for an afternoon meeting, you had another cup as you were preparing. Wednesday night, you were too caffeinated to get to sleep at your normal bedtime so you stayed up a little and binged a show you’ve been wanting to watch. Now it’s Thursday morning and it feels like there’s not enough coffee on the planet to get you through the day. Hello, vicious cycle. It’s an easy pattern to fall into. To crack it, you’ve got to avoid caffeine in the afternoon and evening. Maybe make a deal with yourself not to consume caffeine after noon. And stick to it!

Interference with medications. Many medications become less effective when caffeine intake is too high. Some medications affected by caffeine include: antipsychotics, antibiotics, blood pressure drugs, estrogen, non-steroidal anti-inflammatory drugs (NSAIDs), sedatives, anticoagulants, drugs for Parkinson’s and Alzheimer’s, thyroid medications, cancer medications, antidepressants and more.

Chest pain. The amount of caffeine required to trigger chest pain is pretty high, but it can happen. Chest pain occurs when blood flow to the heart is blocked. Caffeine narrows/constricts blood vessels, and when blood flow to the heart is restricted in this way, chest pain is a possibility. It generally takes a LOT of caffeine to trigger chest pains, so if you drink 1-3 cups of coffee a day your risk is pretty low.


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