Michael Greger M.D. FACLM opens his video, “Does Adding Milk Block the Benefits of Coffee?” with a graph from a study of mortality versus coffee consumption that suggests coffee drinkers live longer than non-coffee drinkers. Why might that be? Coffee may have beneficial effects on “inflammation, lung function, insulin sensitivity, and depression,” perhaps due in part to a class of polyphenol phytonutrients found in coffee beans called chlorogenic acids, which have been proven to have favorable effects in studies where it was given alone in pill form.
Indeed, they have shown beneficial effects, such as “acute blood pressure-lowering activity,” dropping the top and bottom blood pressure numbers within hours of consumption, as you can see in the graph below and at 0:40 in my video. So, which coffee has the most chlorogenic acids? We know how to choose the reddest tomato and the brightest orange sweet potato, indicating that plant pigments are antioxidants themselves. So, how do you choose the healthiest coffee?
More than a hundred coffees were tested. Different ones had different caffeine levels, but the chlorogenic acid levels varied by more than 30-fold. “As a consequence, coffee selection may have a large influence on the potential health potential of coffee intake.” Okay, but if coffee can vary so greatly, what does it mean when studies show that a single cup of coffee may do this or that? Interestingly, coffee purchased from Starbucks had an extremely low chlorogenic acid content, which contributed significantly to widening the range.
Starbucks’ coffee averaged ten times lower than the others. Could it be that Starbucks roasts its beans more? Indeed, the more you roast, the less chlorogenic acid content there is; chlorogenic acid content appears to be partially destroyed by roasting. Caffeine is pretty stable, but a dark roast may wipe out nearly 90 percent of the chlorogenic acid content of the beans. The difference between a medium light roast and a medium roast was not enough to make a difference in total antioxidant status in people’s bloodstream after drinking them, and they both gave about the same boost. Other factors, such as how you prepare it or decaffeinating, don’t appear to have a major effect either.
What about adding milk?