Do the Health Benefits of Coffee Apply to Everyone?

September 13, 2019 0 By William Morgan


“Do the Health Benefits of
Coffee Apply to Everyone?” Three-quarters of American
adults drink coffee, about half of which
on a daily basis. That comes out to a million
tons of coffee every year. Might there be “grounds” for concern? Population studies have found
that coffee drinkers tend to have lower risk of Parkinson’s, less prostate
cancer (especially the women), less liver cancer, less diabetes, liver
cirrhosis, depression among women, and a reduction in mortality overall, such
that coffee drinkers tend to live longer than non-coffee drinkers, with mortality
bottoming out at about four cups a day. But these are all just associations. You don’t know if it’s cause and
effect until you put it to the test. For example, coffee really
does seem to protect the liver. Take people with chronic hepatitis
and have them drink coffee, or not, for a month, then
switch them back. And the coffee really
did seem to help. Similarly, randomize Parkinson’s patients
to get two cups of coffee’s worth of caffeine and get a
significant improvement in movement symptoms
within three weeks. Runners, randomized to drink coffee,
shaved about six seconds off their mile. Weight lifters, randomized to
coffee, can squat more weight, about 600 pounds more worth of reps. And not just athletic performance. A cup of coffee’s worth of caffeine
can significantly improve IELT, which stands for “intravaginal
ejaculation latency time,” from two minutes all
the way up to five. Unfortunately, those effectively
randomized at birth to genetically just have a higher
predilection to drink coffee do not appear to be protected
from diabetes, or depression, or Alzheimer’s, or obesity,
or metabolic syndrome. So it seems the protective associations
may just be due to confounding factors, like maybe those who drink coffee just
happen to exercise more or something. And the same with prostate cancer: no
apparent cause-and-effect relationship, and even the mortality benefit
seemed to disappear. Even if a study did show
coffee drinking could extend lifespan by reducing
inflammation or improving lung function, or insulin sensitivity,
that would mean on average. There is “inter-individual variability”
after consumption of major plant-food compounds,
meaning people may respond differently. For example, how crazy is this: in some
rare individuals, heavy use of caffeine apparently provokes sleepiness. That’s an extreme example. Most of the time it’s just that some
individuals may benefit more than others from the health effects
of different foods. For example, because of differences in gut
bacteria, only a minority of Westerners may derive extra benefit from soy,
as I’ve described before. The most common difference in caffeine
effects is that, while most people metabolize caffeine rapidly, certain
gene variants in liver detox enzymes make some people slow metabolizers. Might that make a difference? Well, habitual coffee consumption
of at least three cups a day has been associated with uncontrolled
blood pressure among older individuals diagnosed with hypertension,
suggesting that moderating coffee intake may be a
good idea for some people. But even if it was cause-and-effect,
that would be on average. What would happen if you split people up
by how fast they metabolize caffeine? Compared to coffee abstainers, those who
have impaired caffeine metabolism genes have an elevated risk of becoming
hypertensive at one to three cups a day, and especially at four or more. OK, but check this out. For the rapid metabolizers not
only was there no excess risk at one to three cups, heavy coffee
drinkers were protected, meaning apparently
the more coffee they drank, the lower their risk.
How do we explain that? Coffee is a complex blend of a vast
number of different compounds. There are protective polyphenol
antioxidants that are beneficial. Coffee beans are, after all, beans— well, actually, seeds, but
seeds are really healthy too. On the other hand, there’s the caffeine,
which can spike adrenaline levels in the blood, but only if
you’re a slow metabolizer. Rapid metabolizers can
clear caffeine so fast that there’s no increase in adrenaline
even at four or more cups a day. And so then you just have the
beneficial polyphenols that actually lower your blood pressure,
hence the benefit overall. Thus, there seems to be a
Jekyll and Hyde aspect to coffee whose overall action on the
cardiovascular system appears to be regulated by that
gene for the enzyme that metabolizes caffeine. The important question, though, is
does it give women larger breasts? W-h-a-t? Young women who drink a lot of coffee
and are rapid caffeine metabolizers have about a half-a-baseball-sized
larger breast volume, which may be a bad thing as breast volume is
associated with breast cancer risk. But no, the important question is
what about heart attack risk? In slow metabolizers, daily coffee
consumption appeared to double the odds of a heart attack, or even
quadruple the odds at four cups a day, whereas in the rapid caffeine
metabolizers, daily coffee consumption was protective, cutting the odds of
a heart attack by more than half, or at least until you get up
to four or more cups a day. The protective effects observed
among rapid metabolizers suggest that the efficient elimination of
caffeine might have unmasked the protective effects of other
phytochemicals in coffee. We think it may be
the adrenaline again, since if you’re a slow metabolizer of
adrenaline, high coffee consumption may put you at risk as well. So, is coffee friend or foe? These studies suggest the possibility
that slow caffeine metabolizers who consume caffeinated coffee
may have an increased risk of cardiovascular disease, whereas fast caffeine metabolizers
may be protected from this risk by the antioxidants and other
beneficial compounds present.