Consumption

I mentioned today I love coffee.  I really really do.  I also mentioned that coffee, or presumably the caffeine in coffee, has been demonstrated to have a positive effect on cognitive performance.  I like this data.  A lot.

I also like this recent article.  It's an overview of some of the effects that have been found related to coffee consumption.

This month alone, an analysis in the Archives of Internal Medicine found that people who drink three to four cups of java a day are 25% less likely to develop Type 2 diabetes than those who drink fewer than two cups. And a study presented at an American Association for Cancer Research meeting found that men who drink at least six cups a day have a 60% lower risk of developing advanced prostate cancer than those who didn't drink any

And it gets BETTER even.

Earlier studies also linked coffee consumption with a lower risk of getting colon, mouth, throat, esophageal and endometrial cancers. People who drink coffee are also less likely to have cavities, gallstones, cirrhosis of the liver, Parkinson's disease and Alzheimer's disease, or to commit suicide, studies have found. Last year, researchers at Harvard University and the University of Madrid assessed data on more than 100,000 people over 20 years and concluded that the more coffee they drank, the less likely they were to die during that period from any cause.

Seriously - that's music to my ears.

But...I also talked today about how one of the reasons that every psychology course has a section on research methods, and one of the reasons that I go on and on and on until you fall asleep spend so much time and energy trying to hammer home research methods is that understanding some of the details and rules about how science is conducted helps us become better consumers of science.  Just because we find a relationship between two variables (i.e. a correlation) doesn't necessarily imply a causal relationship, even it it's something we really really want to believe.

The WSJ article actually does a relatively good job pointing out some of the complications with the rosy view of coffee presented above.  For example, they point out that while certainly those beneficial effects have been noted, negative effects for coffee consumption have also been found in other research.

But those studies come on the heels of older ones showing that coffee—particularly the caffeine it contains—raises blood pressure, heart rate and levels of homocysteine, an amino acid in blood that is associated with stroke and heart disease. Pregnant women who drink two or more cups of coffee a day have a higher rate of miscarriages and lower birth-weight babies; caffeine has also been linked to benign breast lumps and bone loss in elderly women. And, as many people can attest, coffee can also aggravate anxiety, irritability, heartburn and sleeplessness, which brings its own set of problems, including a higher risk of obesity. 

Moreover, as they point out, research on coffee consumption is plagued by many of the same methodological concerns common to most research focusing on lifestyle issues.  For reasons of both pragmatics and ethics, most studies such as the ones cited above involve observational designs.  In other words, people report on their consumption.  As such, there may be something different about regular coffee drinkers than those who abstain, or people's memories may be faulty or incorrect. And lab studies which do control for these factors can be critiqued on the grounds that they are not ecologically valid.  What happens in the lab may not necessarily mirror what happens in real  life.

The authors of the article conclude that while there are some indications that coffee can be a healthy drink, there is not enough evidence to suggest that non-coffee drinkers take up the habit, and that certain groups (e.g. pregnant women, people with high blood pressure) should consider reducing their intake.

As for me?  I'll stick with my caffeine habit.  After all it makes the morning headache go away just tastes so darned good in the morning!