
Consumption of a dark roast coffee blend reduces DNA damage in humans - blopeur
https://www.ncbi.nlm.nih.gov/pubmed/30448878
======
1_over_n
"Funding

This study has been supported by Tchibo GmbH, Hamburg, Germany."

Tchibo is a German chain of coffee retailers and cafés known for its range of
non-coffee products that change weekly.

[https://en.wikipedia.org/wiki/Tchibo](https://en.wikipedia.org/wiki/Tchibo)

Number of locations 700 shops (Germany) 300 (rest of world)

They might want to make some in-store claims about Dark Roast...

~~~
tachyonbeam
I'm generally sceptical of all studies about coffee for this very reason.
There's a lot of bullshit studies around food and supplements funded with
people with strongly vested interests in selling more product. It's a real
problem. For any given supplement, you can often find multiple studies
supporting its use and multiple studies saying it's harmful.

When it comes to coffee specifically, if you listen to the studies about
coffee, it's some panacea full of anti-oxidants. However, it's a stimulant, it
increases cortisol (stress hormone). Stimulants generally makes the body
prioritize immediate energy spending over regeneration/healing. There's been a
study claiming that caffeine decreases neurogenesis, which should negatively
impact both long-term memory and mood.

~~~
rubicon33
To some extent isn't that expected?

Let's face it - who would spend the money to fund a study on a substance
that's been around for hundreds (thousands?) of years?

Probably if you're going to spend the money to investigate it, you expect some
kind of return. So sadly, all these studies end up being funded by people with
an interest in a positive outcome.

The bigger question to me is, does that immediately invalidate their results?

~~~
swsieber
It depends on the ratio of studies funded vs studies published.

I wouldn't be surprised if around 90-95% of special interest funded studies
that aim for a p value of <5% _aren 't published_.

~~~
laingc
> I wouldn't be surprised if around 90-95% of special interest funded studies
> that aim for a p value of <5% aren't published.

This is true of the majority of publicly-funded research, too.

------
dannykwells
If we had even 1 honest meta-analysis for every 10 trials like this, well,
we'd know more than we do now. Small trials with inconsistent/poor designs are
the bane of medical science.

That said, I drink dark roast so this study must be true.

~~~
nabla9
Here is nice meta study of coffee and cancer risk (dna damage and cancer are
probably linked).

[https://www.nature.com/articles/srep33711](https://www.nature.com/articles/srep33711)

> coffee intake was associated with reduced risk of oral, pharynx, liver,
> colon, prostate, endometrial cancer and melanoma and increased lung cancer
> risk.

(Heh. Smokers drink nearly twice as much coffee as non-smokers. Smoking
increases caffeine metabolism. I think this explains the lung cancer risk)

~~~
jimmy1
To your parenthetical comment: May be unrelated, but totally anecdotal,
smokers tend to drink a very light roast that is easily drinkable like a
folgers or maxwell house, maybe a coffee shop light roast, like a Dunkin. I
don't think smokers are downing cups of Starbucks dark blend and if they are
god help their stomachs.

~~~
sp332
Lighter roasts have more caffeine, because the roasting process damages the
caffeine molecule.

~~~
ferrisford
I used to think the same, that roasting burns off the caffeine so lighter
roast = more caffeine.

But when I looked for a source on that one day it seems like that's a myth.
There can be differences based on whether you measure by weight vs volume but
that's about it. [https://www.kickinghorsecoffee.com/en/blog/caffeine-myths-
da...](https://www.kickinghorsecoffee.com/en/blog/caffeine-myths-dark-vs-
light)

So now I just say I like light roasts because I like to taste the coffee and
not the roast.

------
rossdavidh
I drink coffee nearly every day; I am reading this in a coffeeshop. But, p =
0.028? Come on. If you tested for a few dozen things, you would expect to find
at least one that had a p-value like that. Was this pre-registered to look at
only DNA damage, via this metric? Or did they look at 100 different things to
find one with p=0.028?

Of course, if they pre-registered and their theory was that it would reduce
DNA damage as measured in this way, that would be a bit different, but from
this article it's hard to say.

Now, back to drinking my mocha latte.

~~~
longerthoughts
It's a little annoying if they're cherry-picking but does it really impact the
validity of the results? If anything, I'd think they'd have a greater
incentive to skew results if they were specifically testing a theory about DNA
damage.

~~~
pergadad
"I want to prove that it's good for something, but I don't care what it's good
for" is not really a good research question. Then you'll measure 100 things
and only publish the one that makes your intervention look good and possibly
ignore all the ones that make it look bad.

It's also rather useless if you don't at least have some idea of the
mechanism. Coffee has lots of different parts, so what part of it is useful -
is it the caffeine? The tannins? ...? And how does it have this effect? Is it
even the coffee or just that the coffee group took 5 minutes of rest to drink
their brew and that is really the effect?

------
max76
I really hate bad science, and this is an example.

Springer Science+Business Media (the publisher) does not transfer copyright of
the paper from the author to the publisher like many other journals. This begs
the question, why isn't this article open access? The primary author, Dorothea
Schipp, is a statistics consultant in small town Germany [0] not associated
with a University and the blood work was done in Slovakia. No PHDs or MDs
among them. [1].

Digging deeper into their research method [2] the study looked at DNA breakage
over a four month period in blood sampling for a coffee and non-
coffee/caffeine group. I have a few questions about this, mainly around how
effective the time period and method for determining total DNA stability. How
many individual cell gnomes were measured in the before/after? What's the
random variance for genome variability among cells in the same body? I suspect
the variance is high enough to explain their unbelievably low p.

My guess is that the statistician is having fun with p-hacking [3] while
collecting some funding from industry.

[0] [https://en.wikipedia.org/wiki/Rosenthal-
Bielatal](https://en.wikipedia.org/wiki/Rosenthal-Bielatal)

[1][https://link.springer.com/article/10.1007/s00394-018-1863-2](https://link.springer.com/article/10.1007/s00394-018-1863-2)

[2] [https://www.mdlinx.com/journal-summaries/coffee-comet-
assay-...](https://www.mdlinx.com/journal-summaries/coffee-comet-assay-human-
intervention-study/2018/11/20/7549520/)

[3]
[http://psychology.wikia.com/wiki/P-hacking](http://psychology.wikia.com/wiki/P-hacking)

~~~
rv-de
Also the study was ordered by Tchibo - a producer of dark roast coffee. What a
coincidence. So naturally they didn't have an interest in finding that
(assuming that the result is valid at all - which I doubt) tea with caffeine
(or maybe just caffeine pills) has the same effect. Also why did they use a
_blend_ on earth? This study doesn't make sense on so many levels. But nobody
diggs into it so it's successfully feeding the nutrition misinformation circle
jerk.

------
flyGuyOnTheSly
Stopped drinking coffee months ago and I have never felt better. Anxiety is
down. Sleeplessness is down. General mood is up. Best of all, I no longer get
headaches due to Caffeine withdrawal.

~~~
stochastic_monk
When I’m not drinking coffee, I’m less forgetful and think more clearly. I’m
less anxious and better in tune with my body. I also feel more myself.

But I love coffee and am usually consuming it. Thank you for sharing your
experience. I’ll need to try taking a break soon.

~~~
flyGuyOnTheSly
You're welcome!

The taste of coffee is pretty tough to resist, I'll admit!

They do make decaffeinated coffee, although I've never tried it myself.

~~~
uniformlyrandom
I have switched to decaf espresso (for pretty much the same reasons as
outlined above). It does not taste as good, but it is close enough - so it is
a satisfactory substitute for regular espresso.

~~~
ianai
I’ve had some success by mixing in a minute amount of baking soda into the
coffee immediately before brewing. Probably works best for French press.
Literally the smallest amount I could get between my thumb and finger. Ie 1 mg
might be more.

------
nabla9
Quick googling indicates that tea has similar effect
[https://www.ncbi.nlm.nih.gov/pubmed/24585444](https://www.ncbi.nlm.nih.gov/pubmed/24585444)
(very small study but effect size is good), another study is
[https://academic.oup.com/jn/article/138/8/1567S/4750818](https://academic.oup.com/jn/article/138/8/1567S/4750818)

What are the common ingredients in coffee and tea except caffeine?

EDIT:

It seems like black tea also, although I can't make sense of the biological
jargon.
[https://pubs.acs.org/doi/abs/10.1021/jf010875c](https://pubs.acs.org/doi/abs/10.1021/jf010875c)

~~~
gojomo
Why couldn't caffeine be the main mechanism-of-action?

It's a diuretic, so those treated with coffee likely drank more total liquids
during the study, and perhaps flushed more older/damaged cell material.

~~~
Florin_Andrei
Not a biologist or a doctor, but I'm pretty sure you don't pee out damaged
cells.

~~~
gojomo
I was referring to the products of cell degradation. Autophagy – destruction
of cell components or full cells – is a constant, natural, necessary process.
Its waste products have to go somewhere, and biomarkers related to autophagy,
and all the other waste-eliminating functions of the kidneys and liver, can be
detected by byproducts in urine.

It's also the case that full red and white blood cells, and epithelial cells,
are found in urine, and at higher-than-trace levels in various disease
states... but that may just be incidental to kidney/urinary tract functioning.

Still, more peeing from regular use of a diuretic like caffeine, and
commensurate higher water intake, is going to mean more flushing of anything
unwanted in your blood, like the broken DNA strands detected by this study.

Which raises my question: is there really less DNA damage, or has the
detectable evidence of the damage just been swept out more rapidly?

~~~
Florin_Andrei
My semi-educated guess would be that kidneys work best when the volumetric
output is average. These are not 100% passive systems like coffee filters,
they have some active filtering mechanisms. If you overwhelm them with fluid
intake, I would suspect they start to underperform.

------
gojomo
To what extent are "DNA strand breaks", as measured in a blood sample,
correlated with other health outcomes?

Caffeine is a diuretic. The coffee group likely consumed more total liquids in
the course of the treatment. So the mechanism might be simply more flushing of
damaged cells – possibly beneficial, but not unique to coffee.

It's odd for the headline to highlight "dark roast" when lighter roasts
weren't tested, for comparison.

~~~
rossdavidh
Hypothesis: they tested both dark and light roasts, the light roast showed no
effect or a bad one, hence this study. Just an hypothesis, I have no data to
back that up.

------
emptybits
I'm surprised (horrified?) that a control group's DNA deteriorates
significantly enough in such a short trial to use as a comparison. #entropy

~~~
snazz
The study is likely useless since eight weeks total does not constitute long-
term effects. You’d need to do this with a larger sample size over years to
get reliable data.

~~~
rhema
8 weeks is not unusual for a study like this (randomized and controlled).
Almost no study where researchers tell participants what to do will be longer.
Epidemiological studies, of which there are many on coffee, do have more
subjects over years, but rely on self-reported data.

------
brenfrow
I wonder if they took fast vs slow metabolizers into account. It seems to be
healthy only with the fast metabolizers gene:

[https://drwillcole.com/caffeine-one-thing-standing-
optimal-h...](https://drwillcole.com/caffeine-one-thing-standing-optimal-
health/)

If you’re a slow caffeine metabolizer:

1\. Increased risk of high blood pressure (hypertension).

2\. Increased risk of heart attack.

3\. Higher chance of digestive disorders.

4\. More stress and measurable cortisol spikes.

If you're a fast metobolizer:

1\. Longer life.

2\. Faster metabolism.

3\. Better memory and mood.

4\. Lower cancer risk.

5\. Better blood sugar + insulin balance.

I'm most assuredly a slow metabolizer since caffeine makes me feel terrible.

~~~
atorodius
I'm a bit confused by the linked article. The only link to a study I found was
to [1] published _Advances in Psychiatric Treatment_. The other study quoted
is for some specific effects the article mentions. Any idea where the link
between CYP1A2 and caffein comes from?

[1] [https://www.cambridge.org/core/journals/advances-in-
psychiat...](https://www.cambridge.org/core/journals/advances-in-psychiatric-
treatment/article/neuropsychiatric-effects-of-
caffeine/7C884B2106D772F02DA114C1B75D4EBF)

------
akinhwan
Hey guys Pub Med Labs developer here. Check out this very same fascinating
article in the new Labs site and please give us your feedback! Much
appreciated.

[https://www.ncbi.nlm.nih.gov/labs/pubmed/30448878-consumptio...](https://www.ncbi.nlm.nih.gov/labs/pubmed/30448878-consumption-
of-a-dark-roast-coffee-blend-reduces-dna-damage-in-humans-results-
from-a-4-week-randomised-controlled-study/)

~~~
aheyau
The increased white space and font size make it much easier to read.
Responsive layout for mobile phones. Overall a much better experience. Thanks!

------
lvs
Garbage!

Figure 2: The coffee-treated group is anomalously higher in the quantified
metric BEFORE the treatment. This is entirely an artifact of stratifying the
treatment vs. control group prior to wash-out. The only significant difference
is between all groups and the PRE-treatment coffee group.

------
Rafuino
While the research may be compromised by a conflict of interest, I still have
a legit question.

Trader Joe's discontinued my favorite dark roast coffee (Fair Trade Organic
Guatemalan) and nothing I've found has come close to the taste and cost.

[http://www.traderjoesreviews.com/product/trader-joes-fair-
tr...](http://www.traderjoesreviews.com/product/trader-joes-fair-trade-
organic-guatemalan-coffee-reviews/)

Does anyone have a suggestion for me that's ~$10-$12 per pound?

~~~
occamschainsaw
Have you tried Peet’s Big Bang? It’s medium roast but definitely has the
flavor of darker roasts.

~~~
Rafuino
Haven't, no, but I'll swing by and see if I can try a cup. Thanks for the
suggestion

------
eof
> consumed 500 ml of freshly brewed dark roast coffee blend per day,

half a liter per day of coffee is a lot! I wonder if they controlled for
caffeine

some highlights from my reading:

\- 372mg caffeine per day

\- water-only group specifically avoided caffeine

\- coffee/caffeine group had to abstain from all caffeine for 4 weeks before
study (baseline to 300+mg a day is a LOT for someone with no tolerance)

\- they base their claim of the 'darkness' of the roast mattering on other
similar studies, with less pronounced results, that used lighter roasts.

"Among several previous studies of the effects of coffee consumption on DNA
damage, only two were randomised controlled trials, with DNA breakage rather
than oxidative modification of DNA bases analysed [23]. Bakuradze et al. [14]
also studied the effects of coffee C21 consumption, after 4 weeks of
intervention, and found a decrease of DNA strand breaks by 27% in comparison
to the control group with water consumption (p<0.001). Misik et al. [22]
studied a much shorter intervention period (5 days) and a different coffee
type and used isolated lymphocytes. In comparison to C21, the coffee had an
approximately twofold content of caffeoyl quinic acids and trigonelline and
about half of N-methylpyridinium. Therefore, the coffee used by Misik et al.
is a light/ medium roast type while we used here a dark roast blend. We assume
that the different degree of roasting accounts for the different outcome
observed. "

~~~
tracker1
It's 2-3 typical cups of coffee... 2 in the morning and one later in the day.
Now, if it's laced with a ton of sugar or "sugar free" sweetener that
metabolizes like sugar, that's different.

------
asifjamil
The first thing I notice is that both the first and last authors of this paper
are industry-affiliated. Not to say there's anything inherently problematic
with that, but at least raises an eyebrow about the motivation behind this
study.

------
ccnafr
Too bad dark roast coffee also triggers a bunch of digestive tract ailments.
Other than stomach ulcer, hemorrhoids, and all the bowl irritations, dark
roast coffee is just fine. Noooooooooooooooot.

------
Aloha
I'm willing to bet there is another study that coffee causes some sort of
cancer (last I saw it was linked with colon cancer). I'll still drink my
coffee, and tea, and probably continue to consume nicotine in one of many
forms.

Life is too short to worry about maybe, probably is something you should
likely worry about - that why I stopped inhaling burning things to feed my
nicotine addiction, while cancer isnt all that likely, COPD, heart failure,
and others issues sure as hell are.

------
m3kw9
Amongst other effects not stated in this study

------
speakeron
While I'm always happy to hear good news about coffee (although as an espresso
aficionado, I'd be hard pressed to consume half a litre a day), given the
obvious difference between coffee and water, I don't see how this can be a
'single-blind' study.

------
kempbellt
Yeah, this is bullshit.

100 people were a part of this "controlled" study.

Please don't be one of those people that runs around telling people this. This
is nothing more than biased surveying by a weak company in attempt to create
self-promoting propaganda.

Thank you @1_over_n for doing the research

~~~
nabla9
100 people can be enough. Single number like N is not going to tell much.

People should learn the basics of statistics before they start to have
opinions.

~~~
kempbellt
In what world would 100 people be enough to represent anything accurately
enough to make a generalized claim like this? All I know from the article is
that there were 50 women and 50 men involved. It says nothing of age, fitness,
dietary regimen, etc. Based on the "statistics" provided, I could equally make
the claim that "drinking a warm drink reduces DNA damage".

Also, please don't generalize "people" in your backhanded comment. I recommend
that you study up on critical reasoning. Maybe then you would come to
understanding that most "statistics" are unintentionally (or intentionally)
biased, and are therefore bullshit, and not to be taken at face value.

~~~
nabla9
I criticized your backhanded N = 100 comment because it's silly.

Your comment "In what world would 100 people be enough" shows your disbelief
in basic statistics.

In typical well conducted study N=100 participants is close to the minimum
sample size when the population is large.

No statistician says that N = 100 is not enough to represent things accurately
without knowing other parameters and the design of the study. With large
enough effect size N=1 is more than enough and. N = 1800 is enough even if the
population size is infinite in the optimal case.

~~~
kempbellt
You've got me there. I believe most basic statistics are deterministically
useless.

I asked 3 people if they agreed with me. 2/3 said yes. So I guess I'm right

------
sudhakarrayav
I grew skeptical the moment I read "single-blind" test. So, the researchers
know which group is what and that could involuntarily lead them to pick for
what they are leaning to find (given it is funded by a coffee company)

------
devereaux
Odd days: research shows coffee is good for you

Even days: research shows coffee is bad for you

~~~
Symmetry
It's both good and bad for you depending on which health indicators you look
at. People tend to treat "Coffee prevents cancer" and "Coffee raises blood
pressure" as if they contradicted each other but really they don't. The whole
thing is very dose dependant too. Correlationally life expectancy maxes out at
around 3 cups per day but I doubt that's the causal maximum.

~~~
ilaksh
I don't buy it. I love coffee and caffeine in general but it's just a
stimulant.

I personally believe the net effect is to make your body work harder to get
through the day.

I think it's bad unless you were funded by the coffee industry.

~~~
slothtrop
Even if being a stimulant were its only property, what makes it decidedly bad?
Researchers understand it as a stimulant as it is, they're not evaluating its
worth "despite" being a stimulant. If consumption in small doses poses a net
harm for that reason, there ought to be stronger consensus, which is lacking.

------
rdlecler1
As a stimulant coffee could be placing stress on the body leading cells with
damaged DNA to act more aberrantly and subsequenttly rejected by the body.

------
chiefalchemist
"The study comprised two periods of 4 weeks: a preconditioning period, with
daily consumption of at least 500 ml water but no coffee, nor tea, nor any
other caffeine-containing product. During the subsequent intervention period
the coffee group consumed 500 ml of freshly brewed dark roast coffee blend per
day, the control group consumed water instead."

Apparently, it's caffeine, or perhaps hot beverages (as it doesn't seem like
the control drank their water heated).

The information that would help me is an answer to the question: Why?

------
Angostura
... and increases problems with X,Y,Z I wouldn't be surprised to learn, before
anyone thinks about taking this as health advice.

------
Dowwie
Coffee remains one of the few things you can buy the best of, in the world,
for less than $100usd and enjoy for several days.

[http://store.georgehowellcoffee.com/coffees/limited-
roasts](http://store.georgehowellcoffee.com/coffees/limited-roasts)

Only grind what you are going to brew immediately. Use a conical Burr grinder.
Technivorm coffee machine else bonavida.

------
gregorymichael
If this is true, my DNA is so healthy.

------
fbn79
What about [https://www.reuters.com/article/us-california-lawsuit-
coffee...](https://www.reuters.com/article/us-california-lawsuit-
coffee/cancer-warnings-to-be-served-up-with-coffee-in-california-
idUSKBN1I930H)

------
nukemandan
All I can say... "Is Most Published Research Wrong?"
[https://www.youtube.com/watch?v=42QuXLucH3Q](https://www.youtube.com/watch?v=42QuXLucH3Q)

TL;DR: Likely yes. Spinning statistics is not that hard, even with the best of
intentions.

------
franchb
Can't see any evidence with "n=50"...

------
perseusprime11
I have a simple rule in my life: Anything that is addictive is harmful to us.
Coffee falls in that bucket.

~~~
blacksmith_tb
Watch out for carrots[1]. Lots of non-addictive things are also harmful, of
course, but I suppose that doesn't by itself invalidate your principle. In the
case of coffee and tea it seems possible that the benefits outweigh the harm.

1:
[https://journals.sagepub.com/doi/abs/10.3109/000486796090626...](https://journals.sagepub.com/doi/abs/10.3109/00048679609062670)

------
hahamrfunnyguy
Good. I will continue drinking French Roast then.

------
digitalice
hhhhhhmmmmmmmm 4 weeks only?

------
new_guy
>Our results indicate that regular consumption of a dark roast coffee blend
has a beneficial protective effect on human DNA integrity in both, men and
women.

What they established was that drinking water damages DNA. When they drank
coffee there wasn't as much damage. It's a stretch to say that coffee is
providing a protective effect though.

Without denigrating anyone, it's a bad study.

What was the chemical breakdown of the water? Was it tap water? Distilled?
Bottled? Spring? etc.

A better designed study would have groups drinking different kinds of water.
Was the fact that the water was boiled (in the coffee) providing the
protective effect? i.e removing toxins etc, did the kettle they use have a
filter that processed the water, whereas the water was drunk straight from a
tap etc.

Coffee is great though!

~~~
Retra
Coffee contains water. If water is harmful, coffee will be just as harmful
_unless_ it has protective effects.

In any case, you can't say they "established that drinking water damages DNA"
and then go on to argue that they should establish it with another study about
water.

~~~
cbhl
It's not clear to me that the control group drank 500ml of boiled water.

If they're drinking cold tap water, it could be that the act of boiling the
water yields the desired effect. If they're drinking bottled water (and if the
instructions said "drink 500ml of water", this would be my first inclination)
then maybe the DNA damage is being caused by plastic that's leaching into the
water as opposed to any preventative effect in coffee.

~~~
devereaux
If it's the plastic, then we need follow up studies comparing people drinking
coffee in plastic cup vs paper cups vs other non plastic non paper glassware!

~~~
snazz
I don’t think it’s the cup that leeches plastic, unless it contains BPA.

