Coffee Consumption: Evil Foe or Helpful Friend?
Tuesday, November 20th, 2012
As an avid coffee drinker, I was delighted by the recent article published in the New England Journal of Medicine which concluded that coffee consumption was inversely associated with mortality.  Coffee is the most widely consumed non-nutritive food item in the world, available in virtually every country. As such, it has been the subject of intense nutritional research to validate positive and negative health claims. For decades it was thought that coffee consumption in excess of two to three cups per day was detrimental to health. For example, in a study published in 1986, 1130 male medical students were followed over 35 years, and those who consumed five or more cups of coffee per day were 2.5-fold more likely to develop cardiovascular disease. 
However, there has always been controversy about the validity of the apparent detrimental effects. In a follow-up study conducted on 51 000 health care professionals in the US, it was concluded that coffee consumption did not significantly increase the risk of cardiovascular event or stroke.  After years of inconclusive and conflicting data, the recent study which included 229,119 men and 173,141 women (50 to 71 years of age) in the US National Institutes of Health–AARP Diet and Health Study, clearly demonstrated inverse associations for deaths due to heart disease, respiratory disease, stroke, injuries and accidents, diabetes and infections.  Interestingly, the hazard ratios for death (all-cause) amongst coffee drinkers versus non-drinkers decreased in a dose-dependent manner (0.99 for 1 cup/d to 0.85 for 4-5 cups/d).  Unfortunately for those of us who tend to drink six or more cups a day, the hazard ratio begins to increase again and the apparent benefits begin to disappear!
So are we in the clear? Should we up our coffee intake to five cups per day for maximum effect? The short answer is no. This study was conducted in the US and failed to account for coffee preparation methods. In North America the main coffee preparation method is drip-brew with paper filtration. Unfiltered coffee and mesh-filtered coffee (French press and European style), which are popular in Australia, tend to have high levels of cafestol and kahweol which are diterpene compounds found in the lipid fraction of coffee grounds. [4-5] These compounds appear to promote (in addition to a delicious flavour) increased plasma concentration of cholesterol. Importantly, these coffee-borne lipids have been suggested to be the source of the detrimental health associations with increased coffee consumption.  The paper filtration method traps these lipid compounds, preventing their consumption. It appears that the decrease in mortality may only extend to paper filtered coffee, which I have discovered is unpopular in the coffee-loving city of Melbourne. There are numerous antioxidant compounds in coffee which may attribute to the potential benefits of moderate consumption. However, as with all of life’s indulgences, moderation still appears to be the key.