Coffee is
an essential, eye-opening morning ritual for many of us.Whether
it's served in a demitasse mug or a venti mochachino bucket, its thrilling taste is certain like the crow of the morning cock. But at what
point does coffee become your demise?
As
you probably know, coffee's main health concern—its caffeine content—is
also why you drink so much of it. So what exactly is caffeine doing to
your body, and how much of it can you safely handle?
What is caffeine?
Caffeine
is a naturally-occurring crystalline alkaloid derived from the leaves,
seeds, and fruit of a number of plants including the coffee tree and tea
bush, as well as less common yerba maté and guarana berries. Plants
produce the compound as both a natural insecticide against harmful bugs
and as a reward for pollinators.
In humans, however, it acts as a neurostimulant and mild psychoactive,
invoking a temporary state of alertness and focus. In fact, caffeine is
the world's most widely consumed psychoactive drug, and can be found in
everything from coffee and tea to energy drinks and chocolate.
Altogether, some 90 percent of adults in North America consume caffeine
daily in one form or another.
"It
helps people stay alert and stay focused," Lisa Casas, R.D., L.D., a
clinical dietitian at University of Iowa Hospitals and Clinics, told the
University's blog. However, caffeine's boost is transient at best. "It
really doesn't stay in the system very long—it's only about two to three
hours before it is excreted from the body," Casas continued.
How much caffeine in coffee?
Coffee
can contain anywhere from 60 to 120 mg per 8-ounce serving, depending
on how it is brewed. Teas contain far less, averaging 20 to 90 mg per
8-ounce cup, as do soft drinks, which pack around 20 to 40 mg per can.
Even chocolate contains a small amount of caffeine, about 6 mg per
ounce.
Energy
drinks, on the other hand, contain far more caffeine than any of those
potables. A standard 1.93 oz dose of 5 Hour Energy holds a whopping 207
mg, according to a 2010 Consumer Reports study.
Similarly, Monster Energy drinks pack around 160 mg per 16 oz can,
though the 24 oz MegaMonster variant contains 240 mg. Red Bull contains
an equal proportion of caffeine as MegaMonsters (80 mg per 8 0z), though
they're a quarter of the serving size.
However,
all of these drinks pale in comparison to the 5150 Semi Sweet energy
shot. Each 1 ounce dose of 5150 delivers a heart-bursting 475 mg of
caffeine—that's 2.6 times the amount of stimulant you'd get from downing
an 8-ounce Starbucks brew.
So how much coffee is too much?
While some studies have suggested links between caffeine consumption and lower blood pressure, a recent investigation published in Mayo Clinic Proceedings found that a study's participants under the age of 55 who consumed
more than 28 cups of coffee a week—four cups a day—had a much higher
mortality rate than those who drank fewer than that. The Mayo team
examined data from the Aerobics Center Longitudinal Study, a two decade
long survey of the lifestyle habits of nearly 45,000 people, ages 20 to
87, between 1979 and 1998.
While
the study is alarming, it's also important to note that correlation is
not causation. "High coffee consumption could just be associated with
increased death risk," Carl J. Lavie, a cardiologist at the John Ochsner Heart and Vascular Institute in New Orleans and one of the study authors, told Men's Journal.
"We were able to control for smoking and fitness, but not for sleep
deprivation, stressed-out life, and other factors that could play a
part."
"This result is surprising," Rob van Dam,
Adjunct Associate Professor of Nutrition and Epidemiology at the
Harvard School of Public Health, told PBS via email, "because results
from other cohort studies in U.S. men and women suggest that coffee
consumption is associated with a slightly lower risk of premature
mortality."
The Mayo study appears to support another recently published study from the New England Journal of Medicine that
found people with a daily coffee habit had a lower risk of dying during
the 14-year study period than non-drinkers but that effect diminished
the more cups participants drank daily.
Since
caffeine can affect people differently depending on their sex, age,
body mass, metabolic rate, and sensitivity to the stimulant, there is no
hard and fast limit on how much caffeine one can consume in a day. The highest survivable dose on record is a full 100 g. Not milligrams, grams—that's
equivalent to 1,200 cups of coffee in a single sitting. However, it's
safe to say that consuming anywhere near that amount will likely prove
lethal for most people regardless of their tolerance.
The
FDA recommends that people with high blood pressure, heart disease, and
pregnant women keep their caffeine consumption to a minimum. If you're
55 or older, studies suggest keeping it to fewer than four cups a day.
For the rest of us, recent studies suggest that a moderate
intake—between 200 and 400 mg per day—generally doesn't cause long-term
harm for the average healthy adult. More than 600 mg per day—equivalent
to about seven cups of coffee—however, is pushing it no matter who you
are.
If
you experience any of the following symptoms, regardless of how many
cups you've had, you'd best put down that coffee mug and back up off it:
- Insomnia
- Nervousness
- Restlessness
- Irritability
- Stomach upset or heartburn
- Rapid heartbeat
- Muscle tremors, ticks, or twitches
If these symptoms persist or occur regularly, talk to your doctor. And maybe switch to decaf.
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