The current line of reasoning focuses on the fact that coffee contains antioxidants, as well as pharmacologically interesting chemicals like tannins, and even a known anticancer chemical called methylpyridinium.
But the biggest splash by far has been made by researchers studying the link between coffee and Alzheimer's disease. Alzheimer's is a serious problem: half of all people over the age of 85 suffer from the disease.
Alzheimer's happens when plaques build up on the nerve cells in the brain, tangles form within the neural cells, and the cells die. The disease progresses slowly as the brain cells die one by one.
Unless you drink a lot of coffee, that is.
Two studies form the basis of this assertion. Both studies link a significantly decreased rate of Alzheimer's (we're talking a 90% reduction or better) to consumption of between 3 and 5 cups of coffee a day. (The average American drinks between 1.5 and 2 cups per day.)
The first study examined short term memory in mice. Frankly, this study doesn't appeal to me for two reasons:
1. Mice are not people. (I keep having to point that out!) Mice do not get Alzheimer's; not that we can tell, anyway. Mice don't have the level of cognition that makes Alzheimer's a possibility, and how would you be able to tell? IT'S A MOUSE.
2. Short term memory loss is not the same as Alzheimer's. Agreed, it is a symptom. It's most of what people know about Alzheimer's.
But studying short term memory loss and saying it's relevant to Alzheimer's disease is like studying loss of use of the hands and saying it's relevant to people with broken arms. It just… isn't.
Mice who receive the equivalent of 3 to 5 cups of coffee a day perform better on short term memory and cognitive tests. Blah blah blah.
The second study is a lot more interesting. For one thing, it is a study that involves people. For another thing, it has a lot of data. Researchers in Finland followed 1,400 coffee drinkers for twenty years. They found that the biggest reduction of Alzheimer's happened in the group of people who drank that magic amount - 3 to 5 cups a day - since their 40s and 50s.
I know what you're about to say, and I agree. So do the researchers, who have taken a lot of care to point out that "correlation does not equal causation." It could well be that people who drink tons of coffee also chew a lot of gum, and that gum is actually what prevents Alzheimer's. (I mean, not really - that's just a random example, obviously.)
The bigger question is, how much damage do your liver and kidneys endure with that kind of long term coffee consumption? And given that there are only so many caffeinated beverages a person can drink in a day, is it better to prevent Alzheimer's by drinking coffee, or to prevent cancer and heart disease by drinking green tea?
Photo credit: Flickr/bitzcelt