Questions About Coffee and Health: We Have Some Answers

May 13, 2015 · 87 comments
Reid (Detroit)
I would love if you would do a whole post on Tea.
Mitzi (Oregon)
Heartening to see that the coffee I am drinking right now is good for me.
Matthew Walker (Washington, DC)
I would be interested to know what the science has to say about the correlation between coffee and bone density. Does coffee interfere with the bone benefiting absorption of calcium? If so, should those with osteoporosis limit their consumption?
stuart shapiro (Longview,WA)
pls do hot chocolate or hot cocoa
Laura (undefined)
Please do tea! Yes!

Also, one thing to consider is the way they make something "decaffeinated" -- with tea, at least, it is basically by washing it with hot water (what the rest of us would call "brewing" it for a very short period). So maybe the differences are due to the caffeine being washed away, or maybe they're due to some other compounds that are also washed away during the decaffeination process.
PRS (Ohio)
Unfortunately, the observational epidemiological results on tea is all over the map. Unlike for coffee, nothing can be said.

It may be because there are different kinds of tea, different genetic populations studied, and different ways it is drunk, with sugar and milk (e.g. evidence that milk binds with important poly phenols, inactivating them).
babymf (CA)
How much coffee grounds represent 1 cup? A level Tablespoon?
Alan Hayes (Western Massachusetts)
It's fairly imprecise in practice. How big is your cup? A traditional teacup is probably about 6 oz. A small paper takeout cup or a typical ceramic mug is generally 10-12 oz. And in this country at least, we go up from there.

How big is your scoop? Dedicated coffee scoops vary from one to two tablespoons.

The starting point for measuring coffee, as defined by the Specialty Coffee Association of America, a major trade group, is .36 oz or 10 grams of ground coffee per 6 oz cup. I don't know if this is a standard used in these studies, or not, but it's probably a reasonable starting point. 10g/6oz is roughly equivalent to the smaller scoop amount, though the weight to volume ratio of dry coffee is rather variable. The coffee-gentsia, as a rule, weigh their coffee. Not a few weigh the water, for that matter!

So that was probably not a lot of help. Either measure your coffee maker's capacity and use a standard kitchen measure or weight, to dole out the coffee, follow the directions that the manufacturer supplies using their supplied scoop, or just keep doing it the way you are doing it. I do recommend that people come up with a repeatable way of measuring their coffee, and that they experiment with the ratios. It is possible to make coffee either two strong or too weak.
whoandwhat (where)
Start with one coffee measure, which is about a tablespoon, for each 4 - that's 4 - ounces of water. You can add a little water afterwards if that's too strong, but don't run 8 oz through a tablespoon of coffee, it'll be nasty.

The more water you run through the grounds, the more bitter flavors come out. Some bitter flavor can be pleasant and add some snap, too much and it's just yecch.
For this reason it's better to brew it strong and add water than brew it too weak. The results are -not- the same.
Lucille (NJ)
Nowhere in your article or in any of the Q&A do you ever tell us who funded the studies. We're they done by the coffee industry or by scientificly established organizations?
Nancy (Colorado)
Funding source should be required on all these articles reporting on studies of this and that. It can be a small footnote at the end to not take up space, but readers should know this important fact.
Studies of cancer & smoking relationships funded by tobacco companies versus funded by scientifically established organizations, show… guess what?
S.E.H. (Massachusetts)
Very reasonable and balanced rebuttal and addition - thank you.

But it is appalling that Mr. Carroll cites the need of RANDOMIZED CONTROLLED TRIALS as the solution to all remaining questions. True, it will eliminate some bias in these observational studies but we now learn that RCTs, on which "evidence-based medicine" is based, have been more misleading than useful. They are barely reproducible.
The problem is that RCTs by necessity average over a heterogeneous population. The evidence we get applies only for the imaginary average patient. Each patient however, is different, as is briefly mentioned in passing at the end. This should have been the main message.

The days of RCT and evidenced-based medicine of large populations are numbered.
Welcome the era of PERSONALIZED MEDICINE...
PRS (Ohio)
The days of RCTs and evidence-based medicine are numbered?
Unfortunately, they haven't even barely arrived yet!

Personalized genomic medicine, would be great, but it is a long way off.
Obviously, if coffee, or alcohol, or gluten, or statins give your particular biology problems, you should ignore the standard epidemiological advice.

But long live the coming age of evidence-based medicine!
The Pooch (Wendell, MA)
Any study by necessity averages over the sample population, and will report some measure of variance.

Every study has limitations. The key importance of RCT's is that they are _capable of establishing cause and effect_ through an experimental approach, while observational studies can only report association.
Student (Michigan)
Have heart condition and must drink decaf. Anyone suggest a decent brand?
Dean (US)
I drink Starbucks VIA Italian Roast decaf. A little pricey but the only palatable instant decaf I've found.
lou andrews (portland oregon)
it depends on whether you prefer robusta or arabica beans and if you like your coffee to come ground or whole bean. I have no recommendation for any Robusta variety, but for Arabica once opened, ground packaged coffee quickly loses its flavor and essence, say a few days at best. Roasted whole bean coffee can be stored for up to 10 days- two weeks in an air tight container or if you have a vacuum food sealer, (NEVER freeze coffee beans- never!) it keeps for over a month. Starbucks, or any locally roasted variety is good. Best still is to get raw, green beans and roast them yourself every few days, I used to use a popcorn popper, though you need to be watchful and look on the internet for instructions, or simply invest some money and buy a home roaster. Enjoy.
Blake (New York, NY)
Ily makes a quite good decaf although it's somewhat on the expensive side.
eln (Vermont)
I am glad to hear about coffee's beneficial effects, but it is certainly counter-intuitive since coffee is very often used to help people to function when they haven't gotten enough sleep. You'd think that the decreased sleep would have a negative health impact, but that doesn't seem to be the case.
whoandwhat (where)
Noooo, you need your sleep! Once in a while you can short a hour or two, but not often. Coffee should be to make you feel better when you've had your 7 or 8 hours, not to run on empty. Try to cheat nature and it will get the last word.
Sally (New York)
Please do a study on tea.

Thank you.
Daniel Ormand (SF, CA)
I would be very interested in an article on the evidence for tea.
nycJanet (NYC)
This guy should be more precise in specifying caffeinated or decaffeinated drinks next time. As a decaffeinated coffee drinker, I found his article very frustrating to read, to say the least. Thank you, NYT, for clarifying.
iulia Mereuta (rom)
coffe is the drink of gods...that means i m not addicted ,i m divine :)))
Dr. J (West Hartford, CT)
Yay!! I now know what a "cup of coffee" is: 8 oz. Thank you, Dr. Carroll!
ring0 (Somewhere ..Over the Rainbow)
One other effect never mentioned. What is the effect on health of adding milk or cream to one's coffee? A study reported in the NYT a few years back found that adding milk to your tea would mitigate the healthful effects of drinking tea.
Unvarnished Liz (Portland, OR)
I believe this was mentioned in the original article from which all the questions answered in this Q and A came.
Sally (New York)
In your new review of tea research, please explain the effects of adding milk to tea - any new insights and current thought.
Peter Silverman (Portland, OR)
"No one is suggesting you drink more coffee for your health. But drinking moderate amounts of coffee is linked to lower rates of pretty much all cardiovascular disease." I am suggesting it.
LiorSamson (Mass)
"No one is suggesting" is the standard disclaimer also for articles substantiating the beneficial effects of moderate alcohol consumption, especially wine. The preponderance of evidence is that a couple of glasses of red wine a day is good for you. The disclaimers are more about a residual puritanism than about health science.
ABA Comms (20036)
As this article rightly notes, numerous studies have highlighted the potential health benefits of caffeine and coffee, and research continues to add to the growing body of science documenting the ingredient’s positive effects. Meanwhile, centuries of caffeine consumption and extensive study of this ingredient further reinforce its safety. In other words, the billions of people who routinely consume caffeine and coffee can continue to do so with confidence and the knowledge that the ingredient may even enhance health.
-American Beverage Association
Carol (NYC)
A column on tea would be wonderful! Rooibus has a plethora of antioxidants - let's hear about all the health benefits - and there's no caffeine.
C. Vander (District Of Columbia)
White tea, green tea, oolong tea, and black tea all all contain caffeine.
Luckycharms (Allendale,NJ)
Coffee is good for you as it reduces your odds of obtaining Type 2 diabetes. I drank 3 to 4 cups of coffer for about 11 years now. Can't say there is anything wrong with me but lets see what happens in the long run. It's a pleasant surprise to hear that the coffee is somewhat good for you. Cheers.
Arun (NJ)
Yes, please, report on tea.
Greg Shenaut (Davis, CA)
In a small study on the effects of caffeine on blood pressure (N=1), I was able to determine that for some subjects, switching to decaffeinated tea and coffee produced an average 10-20 point decrease in blood pressure throughout the day, and that this decrease persisted for more than a year. Since this effect has not been found reliably in larger, better-controlled studies, the conclusion is that individual differences may be important when it comes to the relation between caffeine intake and blood pressure.
susjones (New York, NY)
What about the effects that caffeine has on your adrenal glands?
Isn't there a difference between one coffee a day (mild Central Nervous System stimulation) and 4 or more cups (constant CNS stim)?
Repeat that on a daily, weekly, monthly, yearly basis...and you have a group of people who have hijacked and overexposed themselves to their stress hormones - how can that not be a problem down the line?
lauren (New York, NY)
I think it is important to note that "decaf" typically doesn't mean "without caffeine". A lot of "decaf" coffee has only a slightly less amount of caffeine in it - especially brands like Starbucks.
lauren (New York, NY)
And often there is a process and a chemical used to "decaffeinate" the beans - which may mean that the difference between the effects of regular coffee and decaffeinated coffee might not be the caffeine difference at all - but the effects of this added "decaffeinating" chemical.
Sarah (Baltimore)
If I am not mistaken it is supercritical carbon dioxide that is used to decaffeinate coffee beans. So I would say that this is not a 'chemical' in the sense you use, it is a solvent that removes the caffeine and of course, does not then, itself, stay with the beans. This 'process' could be considered more analogous to washing than anything else.
NYHuguenot (Charlotte, NC)
I think I read years ago that the process of decaffeinating coffee was discovered by accident when a shipment of coffee beans had lain submerged in sea water.
Derek (New York)
What about acid reflux or heartburn? The problem with coffee is that it's highly acidic, which is why people with this condition should certainly avoid it.
jim (boston)
Every single substance we put into our bodies causes side effects for some people at some time. Those people absolutely should avoid anything that doesn't agree with them, however, their particular sensitivities are not particularly relevant to the majority of people.
Jimmy37 (Baltimore)
Why is it that it seems a new study comes out about coffee drinking every few months, contradicting a study done earlier? Should we actually believe any of it? Are these "studies" an industry all unto itself?
Richard deVries (Taipei)
Yes they are an industry: science.
whoandwhat (where)
Newspaper reports != science. Every metro newspaper has a diet/health section, and they need to fill it somehow. This one isn't too bad, but it's still a newspaper not a science forum.
Jimmy37 (Baltimore)
Is it truly "science" or just data mining for the sake of the "publish or perish" paradigm? Are meta-data studies really accurate?

Stories abound in the financial world about various indicators that are "discovered" as useful for predicting future market directions. Yet, when implemented, they fall flat. Just google "market timing indicator"
Tad Kline (Boulder)
"If we think there’s enough interest in tea, though, we could devote a future column to the evidence on that beverage." Worldwide and, I believe, within the English speaking world, more tea is consumed than coffee - both by dollar value and weight. Does the world market mean nothing to a journalistic inquiry for the Times or its readership? This remark only shows the author's and his editor's biases.
Alan Hayes (Western Massachusetts)
Not sure I can agree with Tad, here. It's a controversial topic, there are a variety of ways to compare the two and, while I don't have time to wade through the competing claims, it's not clear cut.
Bill Sprague (Tokyo)
I stopped drinking coffee several months ago. The jitters that it induces are not cool.
Richard deVries (Taipei)
I don't get jitters I recommend that if you do then you shouldn't drink so much coffee.
Flex (Cairo)
While I totally agree with most of the benefits listed (and glad for it), I think it's wise to advise those with gastric troubles (like gastritis and peptic ulcers) against drinking coffee.
sabatia7 (Berlin, NH)
For most of my life I was a CEO of non-profits with too much responsibility, both internally and externally generated, and drank coffee, always black, from morning 'til eve to keep going. At my peak I was drinking between eight and twelve cups of coffee a day--and getting jittery. About ten years ago a friend suggested that I substitute decaf, which I tried, but it didn't give me the same alert energy. So I started mixing half decaf/half caf. Now I drink as much coffee--mostly French roast--as I want and get all the enjoyment, enough energy/alertness, and no apparent ill effects. Just hoping that decaf has the same benefits, even if minimal.
Sean M (Washington Dc)
Please do a tea article!
Karen S. Voorhees (Berkeley CA)
I second the motion!
Judith Hoover (Kentucky)
me, too.
Accountant (Nashville, TN)
Yes, please!
M (MD)
"In light of this, we should stop telling everyone to avoid it, or judging others for drinking it. We should also stop feeling guilty or feel we need to consume less." I don't think that follows from the data here. What follows is that there may be some health benefits, but there's a whole spectrum of negative effects that aren't quantified here, and you would need to factor those in to make such a statement.

"Data do not support the idea that we are drinking “too much"" Again, that depends on the data. If you are sweating coffee, shaking, irritable, having frequent bowel movements, can't calm down and think clearly, then yeah, you are drinking too much coffee. But those things are hard to quantify, or at least, and whatever studies have been done on those things weren't included here.
jim (boston)
Immoderation is unwise with any substance we put into our bodies and not unique to coffee. How much is too much will vary by individual, but too much of anything is going to be bad for you. Even water can have deleterious effects on you if consumed in too great quantities.
witness (Washington, DC)
Please. Stop beating this dead horse. There are so many critical public health issues where we are blind -- everything from consumption of high-fructose corn syrup to people with gluten rage -- that throwing more time, resources, and money into the decades-long, billion-dollar-bust coffee medical research sinkhole is beyond irresponsible.
Elizabeth (Seattle)
I hardly think the New York Times can be accused of ignoring the deleterious effects of high fructose corn syrup.

The fact is, many people (such as myself) drink 3 - 4 8 oz. cups of coffee per day and it makes us feel good, but we vaguely wonder if it is problematic. Likewise, other drugs such as wine are widely consumed. These are strongly advocated against. It's useful to know whether they are really problems.

The same could be said of many herbs and spices. From nutmeg to turmeric, people ingest all kinds of things which don't contain macro-nutrients or know necessary vitamins, but which seem in some studies, to do something.

Since food is the best medicine, I think these articles are informative.

(But what the HECK is 'gluten rage'? I've prepared food for the gluten intolerant, gluten allergic, wheat allergic, wheat intolerant, and I've never heard of it.)
Adam (Texas)
Yes, I wish the New York Times would write less about coffee, the second most valuable commodity in the world after oil, and more about fake public health crises like gluten rage. Perhaps after that they can cover rice wrath, spaghetti spleen, and maize madness.
Richard deVries (Taipei)
It seems like the scientific consensus is that coffee is healthy in moderate amounts, much like wine and alcohol. I agree - let's move on to a new topic.
rebecca (Bothell, WA)
I love the scent of coffee, hate the taste. I stick to tea for my morning beverage; currently I'm drinking Irish Breakfast (made with leaves) with a bit of milk. Lovely way to get going. Then I switch to unsweetened iced green tea for the rest of the day.

I'd love to see a column about tea's health benefits, both black and green.
Frank (Oz)
I grew up drinking tea - many cups per day. I also carried 3 handkerchiefs as I had a continually runny nose - which I blamed on hayfever.

Moving south to a coffee town, I started drinking coffee - my girlfriend told me 'coffee is bad for you, tea is good for you' - hmmm - I preferred coffee.

My nose had dried up - a friend doctor said I had moved out of the hayfever zone - OK.

Anyways - one day at a loose end I saw a special price for Japanese shiatzu checkup - interested I went along - he asked 'anything you'd like to check?' - I said 'well - my girlfriend says tea is better than coffee'. OK - he said 'raise your arm to horizontal and use your full strength to resist as I push down' - 'first think of coffee' - OK I did so, he pushed down - 'now think of tea' - he pushed down

ah ! - he said, and consolidated his thoughts in English - 'tea is bad for you, coffee is good for you !' - (I guess thinking of coffee my arm was much stronger than thinking of tea)

What !? This was the exact opposite of what my girlfriend had exhorted !

So - I went home and had my first cup of tea in months. Immediately my nose started running and I had to blow my nose. Aha - I was allergic to tea !

Never heard of anyone else before or since - I still like the occasional tea, and blow my nose afterwards - but now I recognise the itchy eyes and allergic reactions as - as much as I like tea - it doesn't like me.
Elizabeth (VA)
Frank, have you tried organic while silver needle tea? It is a very gentle tea and has very little of the natural fluoride content of green or black tea. As a coffee lover (organic lower acid coffee), this white tea is the only one I enjoy. I like to add a little fruit such as a cherry in the cup when it brews.
W Leon (Wash., DC)
I would be interested in similar information for tea.
Adam (Texas)
Definitely interested in seeing the same analysis done for tea! I've mostly switched over to tea, because it makes me less jittery than coffee.

It's interesting that tea seems to have something of the opposite reputation of coffee: drinking tea is often seen as virtuous, with its protective properties attributed vaguely to science-y sounding elements such as antioxidants. Personally, I drink it for the taste and for the caffeine, but I'd love to learn more about its (possible) health effects.
Richard deVries (Taipei)
Living in Taiwan tea is quite popular and so is coffee. Like you say tea is often seen as virtuous and very relaxed but people who drink coffee are seen as 'go-getters'.
Gene Venable (Agoura Hills, Ca)
It's pretty obvious that many people avoid coffee because it makes them "jittery" -- an adjective chosen to minimise this effect -- and many people drink coffee despite that effect. Since coffee is so popular, I wonder what effect mainlining a drug that makes them borderline hysterics, all to help them avoid sleep, which is important to proper brain function -- what effect does tilting our emotions in this direction have on our culture?
Alan Hayes (Western Massachusetts)
I drink the equivalent of four cups of coffee each morning. Don't get palpitations, feel nervous and jittery, or have trouble sleeping. You sound like somebody who ius drinking too much coffee, Gene. Relax!
EEE (1104)
I always feel better when I have my cup.... and, often during the day, I sip.... a 16oz in a thermal mug can last me several hours.... a lot of pleasure for a dollar...
Also, drinking coffee means you're not drinking soda, which is crap....
chris price (santa monica)
Do you know if the benefits are the same for instant coffee as they are for brewed?
NYHuguenot (Charlotte, NC)
The only benefit to instant coffee is learning how bad it tastes and shouldn't be called coffee.
Kip Hansen (On the move, Stateside USA)
Kudos to Mr. Carroll for this bit:

"Moreover, this evidence is epidemiologic, that is, based on observations of patterns. I don’t want to fall prey to the mistake of recommending we change our eating behavior without evidence from randomized controlled trials."

No one should ever ever ever change their eating/drinking habits based on the tiny beneficial/deleterious effects 'found' in epidemiological studies. Such findings almost never relate to any health benefit or health hazard in actual practice. Epidemiological studies are not evidence of "causes" and in most cases are not even dependable evidence of association (mostly because the 'effects' found are so tiny and confounding factors can easily account for any differences found.)

Wait for the real Gold Standard Randomized Controlled Trails (RCTs) -- scientific studies that can actually determine if some one thing causes some effect.

Try to remember the lesson learned from the anti-oxidant craze - Vit E supplements were found, in RCTs, not to prevent cancer or heart attacks at all in the HOPE trials of the late 1990s [ http://www.ncbi.nlm.nih.gov/pubmed/15769967 ] but rather to be potentially harmful. The main study concluded: ".... long-term vitamin E supplementation does not prevent cancer or major cardiovascular events and may increase the risk for heart failure."
PRS (Ohio)
Yes, large, long-term, well-done Randomized Control Trials with "hard" event outcomes are pretty definitive. (Like the 20,000-treatment Women's Health Initiative Dietary Intervention RCT showing no cardiovascular morbidity or mortality benefit to a lower-fat diet.) However, a lot of large, well-done hard-outcome epidemiological studies can also tell us a lot.

Don't forget there has never been a RCT on smoking and lung cancer...
Tuvw Xyz (Evanston, Illinois)
A good German word Genussmittel describes all the substances taken for pleasure -- such as tea, coffee, alcohol, tobacco, and other legal and illegal herbs.
Dear Mr. Carroll, go for all of them! Ordinary coffee served in the US resembles the pee of a pregnant cow, it is not a real strong beverage that one sips (optionally but preferably with a good cigar).
Paul (Queens)
"Ordinary coffee served in the US resembles the pee of a pregnant cow..."
One must wonder what kind of research went into the ability to make this statement with confidence. At any rate, I would keep this guy away from my cows, if I had any...
Honolulu (honolulu)
I find US coffee generally weak and flavorless (I like coffee black), but German brewed coffee was wonderfully strong years ago when I traveled there, a real waker-upper.
Tuvw Xyz (Evanston, Illinois)
"... what kind of research went into ..." -- Just innate ability to distinguish visually the quality of liquids. As to your cows and their owner, I never had the honor of making their collective acquaintance and do not seek such.
David (California)
I would like to hear more about green tea - a habit I picked up in Japan, (which is known for the longevity of its population).
Bill (Ithaca, NY)
I'd point out that I expect the volume of a 'cup' of coffee is likely irrelevant. Just as much coffee bean is used to produce couple of ounces of espresso as to produce 12 ounces of watered-down American style.
Steve (NYC)
Excuse me? If you brew a pot of coffee, each ounce of the coffee in that pot will have the same amount of caffeine and other substances in it as every other ounce in that pot. A 12 ounce cup of that brewed coffee will have twice the caffeine and other substances as a 6 ounce cup. So the volume most DEFINITELY is relevant, when you compare similar preparation methods.
Blue Jay (Chicago)
I would be interested in a column about the health benefits of tea. I drink several cups a day, but then, I reuse the leaves.
margoto (NYC)
I'd like to hear about tea also, both black and green.
Blue Jay (Chicago)
I drink mostly white tea.
Honolulu (honolulu)
So would I. I'd also like to know if the tea was from bags or leaves. I notice that bags are usually used in the West, while leaves are commonly used in the East. The media almost never reports this.