DrG's Medisense Feature Article
COFFEE
COFFEE
by Ann Gerhardt, MD
December 2016
Print Version
One hundred million Americans drink an average of 28 ounces of coffee
every day, but we’re light-weights when compared to the top
ten coffee drinking countries in the world. Finland takes
first prize for guzzling a daily average of 21 ounces per every man,
woman and child.
For years, tea drinkers, health foodies and scientists have indicted
coffee as being unhealthy. Epidemiological studies have pretty much
refuted those claims. Science hasn’t reached a definitive
verdict yet, but so far the alarmists are losing credence.
Both tea and coffee contain caffeine – between 95 and 200 mg per
8 ounces of coffee compared to 14-70 mg for tea. Caffeine is a cardiac,
brain and energy stimulant. It is an alkaloid that occurs naturally in
the leaves, seeds and fruit (beans) of tea, coffee, cacao and kola
trees, as well as >50 other plants. Better mental alertness and
energy after consuming coffee are due to caffeine.
Both coffee and tea contain healthy, naturally occurring chemical
substances. Many are bioactive, often as anti-oxidants. Some people
estimate that there are >1000 such beneficial substances in coffee,
far more than in tea. Scientists attribute the health effects of coffee
to these chemicals.
Coffee is rich in polyphenols, the most abundant anti-oxidants in a
balanced diet. Coffee contains quinic acids, caffeic acid, chlorogenic
acid, phytosterols, flavanols, procyanidins and tannins. A quinic acid
derivative attenuates the activity of fat-making enzymes of the body,
possibly aiding weight control.
Otherwise, coffee contains few nutrients. There’s a little
potassium and only minor amounts of vitamin E, folate, oil, calcium and
magnesium.
The English word ‘coffee’ originates from the Arabic word
“qahwah” or ‘kaweh’, meaning strength or vigor.
Apparently, Ethiopia grew the first Coffea trees. They exported beans
to Yemen, where writers first documented coffee drinking by monks in
the 15th century. Coffee houses opened in Arabia in the 16th century
and in Europe and America in the mid to late 1600s. The Dutch began
growing it on the island of Java, now Indonesia in 1696.
Coffee comes from the seed of the Coffea plant. Two species, C. arabica
and C. canephora (commonly called robusta) account for most of the
world’s brewed coffee. The Minas and Cioccolatato varieties are
arabica. Cherry and Vietnam varieties are canephora (robusta).
Cherry coffee contains the highest overall content of total phenols,
followed by Minas coffee and Cioccolatato with the lowest. Though
Cherry has more total polyphenols, Minas and Cioccolatato coffees
contain the most chlorogenic acid, which is both anti-oxidant and
anti-hypertensive. Intense and prolonged roasting leads to fewer
bioflavonoids, as well as less caffeine.
Health studies: Most of
the information about coffee’s health effects came from following
groups of healthy people over time and seeing what happened to
them. They didn’t omit people with unhealthful behaviors,
like smoking and lack of exercise. They also didn’t assess
coffee type or strength or incidental calories (> 500 in fancy
mocha/latte/sugary drinks). Overall, these surveys found slightly
lower death rates with increasing coffee consumption, with less death
from diabetes and vascular, lung and infectious disease, but not for
deaths from cancer.
Infection: A 2011 study
published in the Annals of Family Medicine found that drinking hot
coffee or tea lessens the likelihood of harboring MRSA in the nasal
passages. MRSA is a bacteria that causes serious infections that
can kill. In coffee, trigonelline, glyoxal, methylglyoxal and
diacetyl are potential candidates for the effect on MRSA. Iced
tea and caffeinated sodas had no effect, so it’s not the caffeine
that does the job.
Cancer: Coffee is
mutagenic in a laboratory test, causing genetic damage that may cause
cancer. Early studies showed a possible connection between coffee
and kidney, bladder and pancreatic cancers. With time however,
studies involving huge numbers of people debunked those suspicions.
The only study that linked colon cancer to coffee looked at Seventh Day
Adventists’ health outcomes. They are non-smoking,
non-alcohol drinking vegetarians in whom colon cancer is
infrequent. Any amount of coffee increased their cancer death
rate.
On the other hand, coffee may protect against primary liver
cancer. In one Finnish and three Japanese studies, liver
cancer risk progressively declined as coffee drinking increased from
one to eight cups daily. At eight cups daily the risk was cut by
two-thirds. The association was not affected by age, tobacco use, how
the coffee was prepared, alcohol consumption or weight, even though
coffee drinkers tended to weigh and smoke more.
Contrary to common thinking, coffee doesn’t cause fibrocystic
breast disease (or breast cancer). The exceptions may be some
women with slow caffeine metabolism who are at higher risk for it.
Diabetes: Women who drink
six or more cups of decaffeinated coffee a day are 33 percent less
likely to develop type 2 diabetes, a disease that affects more than 18
million Americans, according to a study in the Archives of Internal
Medicine.
The more coffee guzzled by Finnish people, the fewer new diabetes
diagnoses. Drinking more than five cups per day reduced new
diabetes risk by over 50%. The effect plateaued in men at 5-6
cups daily, but kept improving in women who drank progressively more
coffee. Pooled data from multiple studies show that 3-4 cups of
coffee daily reduces new diabetes risk by about 18-31%, with a 5-9%
risk reduction for each additional daily cup of coffee. Three to
four cups of decaffeinated coffee daily reduced diabetes risk by
23-46%, so the effect is not due to caffeine-induced hyper-metabolism.
Cardiovascular:
Short-term caffeine ingestion may cause irregular heartbeats, rapid
heart rate and jitteriness. But a 2009 analysis of 21 large
studies of healthy people indicated that the risk of
heart attack and cardiac arterial disease
was reduced by 18% in female and 13% in male coffee drinkers.
Excessive coffee consumption raises
homocysteine
levels, which are associated with vascular disease and heart
attacks. Apparently this effect is offset by other, beneficial
effects of coffee’s bioflavonoids.
Drinking unfiltered coffee prepared by boiling or using a French press
raises total and LDL-
cholesterol
because of high concentrations of cafestol and kahweol. A paper filter
traps these compounds, so most coffee consumed in the U.S. won’t
raise cholesterol.
A 2011 analysis of 11 studies following healthy people for 2 to 21
years suggested that
stroke
risk is least (17% lower) when drinking 3-4 cups of coffee daily.
Risk is higher with high and low intake.
A 2012 analysis of 5 cohorts (healthy or post-heart attach) over 8-35
years, found slightly less
heart
failure in people who drank any amount of coffee.
A 2011 analysis of 6 healthy cohorts over 6.4-33 years showed no excess
of new
high blood pressure
diagnoses in coffee drinkers. Though caffeinated coffee bump up blood
pressure by constricting blood vessels soon after drinking it, it
doesn’t cause sustained hypertension throughout the day.
That’s because habitual caffeine consumption induces a type of
‘tolerance’ that relaxes blood vessel walls, so the blood
pressure decreases. This is why caffeine
withdrawal causes a headache –
the constricting effect goes away faster than the dilating effect, so
the brain’s blood vessels expand.
Osteoporosis: Coffee
drinking doesn’t affect bone density or cause osteoporosis,
except in elderly white women who don’t consume enough calcium.
Hydration: Coffee
contains water, but it doesn’t help to hydrate, due to the
diuretic effect of caffeine. Too much caffeine without extra
water can dehydrate, causing constipation, fatigue and joint pain.
In 1903, a passage
in the Journal of the American Medical Association summarized a century
of studies not yet done: “Notwithstanding the scare
advertisements of health substitutes for coffee, says the
American Journal of Pharmacy, there
is no cause for apprehending danger to the race at large from
coffee-drinking. ... The life-insurance companies, constantly warring
against all that lessens longevity or conduces to abnormal organs,
nerves and actions, seem content to accept the use of coffee as one of
the ordinary elements of every-day life.”