Caffeine is Not Good for Your Health
Table of Contents
Effects of Caffeine
The
most obvious effects of caffeine in non-pregnant adults are cardiovascular and
neurobehavioral. Knowledge of the effects of caffeine on the nervous system
dates back centuries, to the time when Ethiopian shepherds noticed that their
sheep stayed awake all night after grazing on wild coffee cherries.
In fact,
caffeine is the most widely consumed behaviorally
active substance in the world, with the U.S. per capita consumption at nearly 3.5 kg of coffee per
year, or more than 150 mg of caffeine per day.
Caffeine,
like nicotine, albeit to a lesser extent, meets some of the criteria of the
World Health Organization and the American Psychiatric Association for a drug
of dependence and acts on the dopamine system in the same way as amphetamines
and cocaine. Caffeine and its
metabolites are known to cross the blood-brain barrier readily in adults and fetuses alike.
Intake
of caffeine during pregnancy or the early postnatal period would be expected to
have similar or more profound cardiovascular and neurobehavioral effects on fetuses and infants than on the caffeine-consuming mothers.
This
is because of caffeine's ready passage through the placenta, its presence in
breast milk, and its increasing half-life during pregnancy (up to 11 hours late
in pregnancy) and in infants (up to 100 hours), the smaller body mass of fetuses and infants, and the inability of the fetus and
neonate to detoxify caffeine.
Changes
in fetal heart rate and breathing patterns have been noticed even when maternal
intake of caffeine is moderate and when it has no apparent effects on the
mother.
In
animals, in utero or early postnatal exposure to
moderate-to-high doses of caffeine has been associated with decreased brain
weight and alterations in brain development and in learning and memory, and it
has been associated with an increased incidence of apnea in adult rats.
Unfortunately, the results of the few studies of the neurobehavioral effects in
children after in utero or early postnatal exposure
are conflicting.
There
may be subgroups of pregnant women and children who are particularly
susceptible to the effects of caffeine. Usually, legal regulation of allowable
levels of exposure to a chemical includes a safety factor of 10 to 100 when
data are extrapolated from animals to humans, in order to protect the most
susceptible.
However,
many of the effects of caffeine in animals occur after doses that are within
the range of human consumption, once metabolic differences among species are
taken into account.
Several factors
alter susceptibility to the effects of caffeine, including exposure to other
substances. For example, the half-life of caffeine is halved in smokers and
doubled in women taking oral contraceptives.
Caffeine
may increase the cancer causing potential and other adverse effects of substances
such as alcohol, nicotine, and certain drugs.
Also, infants with poor nutritional status may be particularly
vulnerable to the neurochemical and concomitant
neurobehavioral effects of caffeine.
Given
these considerations, what is the appropriate course of action for clinicians
and policy makers? In 1981, the Food and Drug Administration (FDA) advised
pregnant women to "avoid caffeine-containing foods and drugs, if possible,
or consume them only sparingly."
This
advisory has not percolated down to the general population. And no advisories
have targeted breast-feeding women or parents of young children. In part
because of our own dependence on our morning cup of coffee, and because of our
inability to find strong associations with effects on health in humans, we have
accepted that more than 75 percent of pregnant women consume caffeinated
beverages.
In
1997, the Center for Science in the Public Interest petitioned the FDA to
require that caffeine content be disclosed on food labels, but Congress has not
yet acted. Food labeling is an appropriate first step
in educating the public and should be undertaken.
In the meantime, health care
providers should continue to counsel women who are pregnant or breast-feeding
to limit their caffeine intake.
Coffee May Damage Blood Vessels
Drinking
coffee has potentially harmful effects on blood vessels, according to new
research. Australian researchers presented data linking caffeine consumption
with alterations in the aorta, the main artery supplying blood to the body.
In
the study, 18 middle-aged healthy volunteers consumed 250 mg of caffeine
(equivalent to 2 or 3 cups of coffee).
The
results showed that caffeine led to a loss of aortic elasticity, and raised
blood pressure.
In
another study of fifteen healthy volunteers, Swiss researchers measured blood
pressure, heart rate and other parameters before and after drinking coffee
(triple espresso), decaffeinated triple espresso, getting an intravenous
infusion of caffeine, or placebo.
The
results showed, for the first time, that coffee drinking results in a
pronounced blood pressure increase, although this effect was only apparent in
non-habitual coffee drinkers, but not in regular coffee drinkers.
Caffeine Linked to Diabetes
Preliminary
findings from a small study suggest that drinking moderate amounts of coffee
may put healthy individuals at risk for decreased insulin sensitivity, or an
inability to process blood sugar efficiently. Decreased insulin sensitivity is
a precursor to diabetes.
The
finding may have serious health implications, especially when superimposed on
already-disturbed glucose tolerance or established type 2 diabetes.
Caffeine
reduced insulin sensitivity by 15%. The decrease in insulin sensitivity was
comparable to the increase in sensitivity produced by taking diabetes drugs.
The
caffeine group also had higher blood levels of free fatty acids than their
peers in the comparison group, the report indicates.
Caffeine's
ability to decrease insulin sensitivity could occur because the drug boosts
levels of free fatty acids, as well as the hormone epinephrine. The caffeine
group exhibited a five-fold increase in blood levels of the hormone.
Coffee, Tea, or Stress-Free?
85%
of U.S. adults consume caffeine daily and they are prone to
increased blood pressure, meaning greater chances of heart disease, and feeling
more stressed than if they didn't drink their coffee, cola or tea.
The Duke University research team found that even if people don't consume
caffeine after 1pm, the effects
remain until they go to sleep.
That's because caffeine takes a long time to
deteriorate in the body - twelve hours after consumption, the body still
contains one-eighth of the original amount of caffeine. With regular
consumption, these long-lasting effects could increase the risk of heart
disease.
In
addition, any disorder related to stress, such as the type 2 form of diabetes
or social anxiety, can be adversely affected by caffeine consumption.
In
the study, 47 regular coffee drinkers consumed 500 milligrams of caffeine -
about the same as four 8 ounce cups of coffee -- in the form of two pills, and
no later than 1pm.
They took these
active pills one workday, and inactive pills the next
day, never knowing which type of pill they were consuming. The researchers
monitored their blood pressure, heart rate, and quality of specific substances
in their urine.
The
subjects showed higher stress levels on days they consumed the caffeine pills,
and produced 32% more epinephrine, a stress hormone. They also had slightly
higher blood pressure with the caffeine pills.
Caffeine Increases Estrogen in Women
According
to the researchers, women who drank the most coffee had higher levels of estradiol, a naturally occurring form of estrogen, during the early follicular phase, or days 1 to 5
of the menstrual cycle.
Higher
estrogen levels would not be beneficial for women who
for example have endometriosis, breast pain and family histories of breast or
ovarian cancer, especially arising premenopausally.
The
study included nearly 500 women aged 36 to 45 who were not pregnant,
breast-feeding or taking hormones. All women answered questions about their
diets, smoking habits, height and weight. Researchers measured the women's
hormone levels during days 1 to 5 of their menstrual cycle.
Women
who consumed more than one cup of coffee a day had significantly higher levels
of estrogen during the early follicular phase of
their menstrual cycle.
Caffeine
intake from all sources was linked with higher estrogen
levels regardless of age, body mass index (BMI), caloric intake, smoking, and
alcohol and cholesterol intake.
Women
who consumed at least 500 milligrams of caffeine daily, the equivalent of four
or five cups of coffee, had nearly 70% more estrogen
during the early follicular phase than women consuming no more than 100 mg of
caffeine daily, or less than one cup of coffee.
Dr. Mercola's Comments
Caffeine
is the most widely used and cheapest drug in the world. If you can't go a day
without a cup of coffee, chances are you're addicted.
While I believe that
coffee and caffeine are far less dangerous than fruit juice or soda, it is
still wise to limit, and if possible, eliminate its use.
There
are numerous health risks involved with drinking coffee. Some associated risks
include increased risk of stroke and rheumatoid arthritis. Other studies have
shown that caffeine leads to a loss of aortic elasticity and raises blood
pressure.
Coffee
drinking has become a growing problem for women, as coffee should NEVER be
consumed during pregnancy. It also appears that coffee consumption is
associated with increased estrogen levels, which
means an increase for breast and endometrial cancer.
Despite
this information, it still is a safer beverage than soft drinks or fruit
drinks. Ultimately, the healthiest thing for you to drink is pure water.
However, if you MUST have a cup of coffee, there are a couple healthy tips you
should consider to reduce the chance of harmful effects:
Use
organic coffee -- As I alluded to above, coffee is a heavily sprayed crop.
Drinking organic coffee may reduce or eliminate your exposure to toxic
herbicides, pesticides and fertilizers.
-
Look for "Swiss Water Process" decaf -- If you are going to drink decaffeinated coffee, be
sure that it is one that uses a non-chemical based method of decaffeination.
The "Swiss Water Process" is a patented method and is the best
choice. Most of the major brands are chemically decaffeinated, even if it says
"Naturally Decaffeinated" right on the container. If you are unsure
of the methods, contact the manufacturer.
-
Leave out sugar and milk -- These are actually much worse for you than the
coffee itself. Don't compound possible detrimental health effects by adding
milk or sugar to your coffee.
-
Use unbleached filters -- If you use a "drip" coffee maker, be
sure to use non-bleached filters. The bright white ones, which most people use,
are chlorine bleached and some of this chlorine will be extracted from the
filter during the brewing process.
References
-
The Truth About Caffeine (Especially During Pregnancy)
-
"Coffee May Damage Blood Vessels"
-
"Caffeine Linked to Diabetes"
-
"Coffee Increases Estrogen in Women"
-
"Just One Cup of Coffee A Day Creates an Addiction"
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