Tuesday, December 04, 2012

Science continues to confirm that drinking coffee is good for you

One of the wonderful things about science is that, if you wait long enough, it will eventually discover that things you like to eat or drink, but are supposed to be bad for you, are actually good for you.  That has been happening with coffee for a while. (For some previous reports, see here & here.) A recent wrap-up in the Atlantic is even titled "The Case for Drinking as Much Coffee as You Like". Some highlights:
"What I tell patients is, if you like coffee, go ahead and drink as much as you want and can," says Dr. Peter Martin, director of the Institute for Coffee Studies at Vanderbilt University. He's even developed a metric for monitoring your dosage: If you are having trouble sleeping, cut back on your last cup of the day. From there, he says, "If you drink that much, it's not going to do you any harm, and it might actually help you. A lot."

Officially, the American Medical Association recommends conservatively that "moderate tea or coffee drinking likely has no negative effect on health, as long as you live an otherwise healthy lifestyle." That is a lackluster endorsement in light of so much recent glowing research. Not only have most of coffee's purported ill effects been disproven -- the most recent review fails to link it the development of hypertension -- but we have so, so much information about its benefits. We believe they extend from preventing Alzheimer's disease to protecting the liver. What we know goes beyond small-scale studies or limited observations. The past couple of years have seen findings, that, taken together, suggest that we should embrace coffee for reasons beyond the benefits of caffeine, and that we might go so far as to consider it a nutrient.

The most recent findings that support coffee as a panacea will make their premiere this December in the American Journal of Clinical Nutrition. Coffee, researchers found, appears to reduce the risk of type 2 diabetes. [....]

And most concerns about caffeine's negative effects on the heart have been dispelled. In June, a meta-analysis of ten years of research went so far as to find an inverse association between habitual, moderate consumption and risk of heart failure. The association peaked at four cups per day, and coffee didn't stop being beneficial until subjects had increased their daily consumption to beyond ten cups. [A caveat:  That holds for the general population. I gather from other sources that caffeine is not a good idea for people with certain specific heart problems.—JW]

Caffeine might also function as a pain reliever. [....]  The data is even more intriguing -- and more convincing -- for caffeine's effects as a salve against more existential pains. While a small study this month found that concentrated amounts of caffeine can increase positivity in the moment, last September the nurses' cohort demonstrated a neat reduction in depression rates among women that became stronger with increased consumption of caffeinated coffee.[....]
Etc.  And, apparently, it's not just the caffeine.
"Coffee and caffeine have been inexorably intertwined in our thinking, but truth is coffee contains a whole lot of other stuff with biological benefits," said Martin. [....]

So aside from caffeine, just what are you getting in a cup, or two, or six? Thousands of mostly understudied chemicals that contribute to flavor and aroma,including plant phenols, chlorogenic acids, and quinides, all of which function as antioxidents. Diterpenoids in unfiltered coffee may raise good cholesterol and lower bad cholesterol. And, okay, there's also ash which, to be fair, is no more healthful than you would think -- though it certainly isn't bad for you.

[....] When the Harvard School of Public Health visited the Health Professionals Follow-Up cohort in May 2011, it found that coffee's protective effects extend only to some types of prostate cancer (the most aggressive types, actually). In a separate study of the same population from this past July, they also found a reduced risk of basal cell carcinoma with increased caffeine intake.

The association was strongest for those who drank six or more cups per day.

That same high dosage is also effective in fighting against colorectal cancer, according to a prospective study from June of almost 500,000  adults conducted by the American Society for Nutrition. [....] A meta-analysis of 16 independent studies this past January added endometrial cancer to the group of cancers whose relative risk decreases with increased "dosage" of coffee. And in 2011, a large population of post-menopausal women in Sweden saw a "modest" reduction in breast cancer risk with immoderate consumption of 5 or more daily cups. [....]

If you have fatty liver disease, a study from last December found that unspecified amounts can reduce your risk of fibrosis. [....]
Alas, every silver lining has its cloud. We all know that coffee can be a potent drug, especially when you're just starting to drink it in significant quantities. (So children and pregnant women might want to be careful about their caffeine intake.)  And some people develop a physical dependence on caffeine so strong that they get headaches in the morning if they don't drink coffee. The article mentions that "there is still information working against coffee" (and gives some examples). More important:
Of course, what we choose to add to coffee can just as easily negate the benefits -- various sugar-sweetened beverages were all significantly associated with an increased risk of diabetes. A learned taste for cream and sugar (made all the more enticing when they're designed to smell like seasonal celebrations) is likely one of the reasons why we associate coffee more with decadence than prudence.
So we're still waiting for science to prove that cream and sugar are good for us. But in the meantime:
The evidence remains overwhelmingly in coffee's favor. Yes, it was observational, but the study published in May in the New England Journal of Medicine looked at hundreds of thousands of men and women and found this bottom line result: people who drank coffee lived longer than those who didn't.

And the more they drank, the longer they lived. If you're into that sort of thing.
A doctor friend of mine suggested to me once that, based on the latest research, a health-food diet should emphasize dark chocolate and red wine. Afterward, it seems, we should have another cup of coffee.

Long live science!
Jeff Weintraub

P.S.  As I noted in 2006,  some scientists still seem determined to show, despite everything, that coffee is somehow bad for us:
Still, some experts believe that coffee drinking, and particularly caffeine consumption, can have negative health consequences. A study published in January in The Journal of the American College of Cardiology, for example, suggests that the amount of caffeine in two cups of coffee significantly decreases blood flow to the heart, particularly during exercise at high altitude.
So if you're a heavy coffee drinker, it may be that you should avoid jogging in Bolivia. But really, is that the best they can do?