Coffee: The good, the bad and the likely

As one of the most popular drinks in the world, the routine consumption of coffee has stirred up quite a lot of inquiry as to how the jittery beverage affects human health. Is there truth to the big claims made about this tiny bean?

The origin of coffee use has long been shrouded in myth. It is said that ages ago, a young Ethiopian shepherd noticed that his goats had an ardent taste for a particular berry. After indulging, the herd became restive and active throughout the night. Confused, the young man reported the spectacle to the wise priests at his local monastery. The curious clerics decided to brew up a drink from the berries, and to their pleasant surprise, found it helped keep them roused for long hours of nightly prayer.

The drink’s popularity quickly spread – by the 18th century, coffee had become a staple of many Middle Eastern and European households -and since then, its use has only increased. Last year alone, the population of the United States consumed nearly 1 million metric tons of coffee (that’s 4kg of coffee per person). Because of its prevalent usage, epidemiologists have long been interested in the physiological effects of coffee; yet most investigations into its consumption have not arrived at credible conclusions. Despite this lack of robust evidence, highly embellished and often warped claims about the popular brew frequent the news. [share_this_post]

Most health hype surrounding coffee is attributed to a molecule called Chlorogenic acid (CGA). While coffee beans (green or roasted) contain abundant amounts of CGA, the actual health benefits of this molecule seem to be greatly exaggerated.

Most biochemical investigations support the notion that CGA is an antioxidant that reduces damage caused by free radicals (reactive molecules that harm DNA) Unfortunately, like many studies of this type, the quantity of CGA used is far in excess of the amount that is actually absorbed by the human digestive tract, even after drinking several cups of coffee. A further limitation of these studies is the use of cells grown in Petri dishes – these experiments do not replicate the complexity of living organisms or free radical generation.

Beyond these technically correct but inapplicable studies are other unconfirmed assertions that CGAs can directly reduce the risk of hypertension and promote weight loss. The observations linked to incidences of hypertension in rats were never significantly reproduced in human studies. Meanwhile, the false weight loss claims, pertain to slight but verifiable increase in metabolism that occurs when coffee is ingested. In fact, the researchers who report this finding admit that their attempt to demonstrate an increase in fat oxidation (“burning”) was not achieved.”

More ambitious claims about coffee have also fallen short when the science is critically reviewed.  A team recently compiled information from patient records and found a correlation between coffee consumption and lower cancer incidence. Beyond the attention-grabbing headlines it generated, non-standard reporting metrics and the omission of certain data make the claim of a 3% reduced cancer risk contentious.  Similar concerns are associated with a study claiming that coffee drinkers had a lower risk of type 2 diabetes. This finding was complicated by a lack of indisputable experimental evidence connecting coffee ingestion to glucose or insulin levels – the main readouts for diabetes.

Fortunately, most of the negative health claims associated directly with coffee drinking are just as ambiguous as the positive ones. The most severe reported effects are caffeine withdrawal symptoms. There are also reported instances of caffeine lethality, but these fatalities almost always associated with overdoses of caffeine pills or energy drinks.

So what does coffee do? The most substantial effect of coffee is associated with caffeine’s effects on the brain. For reasons still not fully understood, caffeine has the ability to antagonize adenosine receptors. These receptors are found both on cells which regulate dopamine levels in pleasure-inducing neruons and in the glands that regulate the body’s response to stress. The abnormal firing these cells caused by caffeine, fools your body into thinking it is content and anxious at the same time. This creates an emotional boost coupled with increased heart rate and blood flow. Moreover, this stimuli excites the parasympathetic nervous system, eliciting a mild ‘fight or flight’ response, leading to heightened alertness.

As of now, we do not understand much more than the restless Ethiopian shepherd about the health benefits of coffee. No irrefutable health improvements or detriments can be correlated with moderate or even zealous coffee drinkers (Although if someone has a health issue that could be exacerbated by increased heart rate or anxiety, it may be wise to consult with physician). In spite of this, investigations studying novel chemical components like those found in coffee beans or other plants do offer promise and insight to new possible pharmaceutics, warranting further analysis of medicinal compounds which may be present in plants.

For a much more in-depth review on the biochemistry of coffee click here

Image credit: Peruvian coffee shop by Kenric Hoegler, modified with gimp2 software, molecule of caffeine from wikipedia

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