Science in Caffeine and Coffee

We've heard it on the news time and again... "food study X says drinking coffee everyday is good for your health". [Two weeks later] "food study Y finds those who don't drink coffee live longer". I'm waiting the headline that reads "research suggests we don't really know much about the health effects of our food and drink".

To be fair, coffee is actually one of the most studied and understood components of our diet. And this is understandable, considering the millions of people (myself included) who have made coffee an integral part of their morning routine. There's even a website dedicated to collecting information on coffee health studies. And so I delved into the realm to see what conclusions I could find surrounding coffee health, specifically related to caffeine, its primary active ingredient.

When you drink coffee (or other caffeinated beverages) the caffeine is digested by the small intestine, metabolized in the liver, and distributed to the rest of the body. This process takes about 45 minutes from ingestion, although some of the effects can be felt in as early as 15 minutes. Caffeine acts as a competitive inhibitor to the degradation of cyclic adenosine monophosphate (cyclic AMP), due to its similar structure (pictured right). This leads to a buildup of cyclic AMP, which is responsible for most of the pharmacological effects of caffeine that we see. These effects include:

• Increased strength of the sympathetic nervous system's response (fight-or-flight response).
• Increased metabolism through promotion of fat lipolysis and fatty acid oxidation.
• Increased athletic performance through increase in serotonin levels leading to increase in the firing of skeletal muscle motor neurons.
• Increased mental performance through an increase in cerebral blood flow leading to increased efficiency of neurotransmitters.
• Increased urination through stimulation of the urinary tract, especially in those who are not consistent coffee drinkers or who ingest it after withdrawal.

When we drink too much coffee at one time or in a day, we become "over-caffeinated", and can experience jitteryness, fatigue, anxiety, and headaches. For adults, too much caffeine can mean anywhere from 4-12 mg per kg body mass, which I will note is a very sizable range. For me (a 150lb male), that means I should limit myself to anywhere between 3 and 9 cups of filtered coffee a day (a typical cup contains 85mg caffeine). I rarely drink more than 3 cups in one day, but I'm pretty sure it's a scientific fact that 9 cups would cause my head to explode.

Those of you who think 9 cups/day is nothing are probably more familiar with withdrawal symptoms. Caffeine has a half life of 3-5 hours; this means by tomorrow only about 0.4-1.6% (virtually none) of the caffeine you ingested from this morning's "dose" will remain. People who have been become accustomed to having caffeine (especially larger amounts) in their system may experience headaches, difficulty sleeping, poor concentration, or pain in joints and the stomach from a withdrawal = not a fun day.

When I started looking at studies of the long term effects of coffee and caffeine, the science became less concrete. There are a litany of perceived benefits and some drawbacks, but for low/moderate consumption most of the effects were very slight or small. I won't get into describing them all, but I encourage you to check them out yourself if you're interested. Or just read the news and wait for the next one to pop up, probably tomorrow…

All food health studies, in my book, should probably be taken with a grain of salt given the number of variables that are unique to each person's genetics, diet, and lifestyle. It's much easier in some ways to study the mechanisms and the short-term effects that foods produce every time we partake. Though I found the resounding conclusion of most long-term studies is moderation - don't make a habit out of drinking too much coffee, and you're probably OK.

Also, maybe avoid being like my college roommate who decided to "triple brew" a few cups before an exam, or my other friend who mistakenly prepared his morning cup using espresso beans... Again, not a fun day.

References

Coffee and Health

Caffeine Pharmacology