Why Freshness Matters: The Health Benefits of Coffee
After years of debate over the risks and benefits of coffee, the pendulum seems to have swung decisively in one direction: coffee can, in fact, be good for your mind and body. Your daily (or thrice-daily) cup of coffee has antioxidants and caffeine, in addition to other compounds that haven't yet been studied closely and aren't as clearly understood. Taken together, they have the ability to fight melanoma, diabetes, depression, gout, aging, memory loss, and quite a bit else besides. It's also a major source of antioxidants, to the point where most Americans' antioxidant intake comes primarily from coffee (though a diversity of sources is advised, since different foods contain different antioxidants).
Roasted coffee contains over a thousand chemical compounds that between them are responsible for the aroma, body, flavor and health benefits of coffee. This includes nonvolatile alkaloids like caffeine, theophylline (also found in green tea), and liberine. Coffee also contains proteins and free amino acids (catalase, polyphenol oxidase, and others), carbohydrates (especially arabinose and galactose, which boost the immune system), lipids (stearic, linoleic, palmitic and other fatty acids, esters and amides), nonvolatile chlorogenic acids (which are responsible for the antioxidant benefits of coffee, and which modulate taste) and volatile compounds like short chain fatty acids, many of which are lost during roasting. Many of the volatile compounds found in green coffee beans are lost during roasting, which is probably a good thing, since several cause nausea and vomiting.
Of course, given the health claims made for coffee, it's hardly surprising that while some of us are smelling VOCs, others are smelling profit. The Healthy Bean, for instance, promotes their product as "the world's first healthy coffee," and goes further to state that the antioxidants they add -- "sourced from the highest quality laboratories in the nutraceutical industry" -- are lost during the roasting process. Serial entrepreneur Dave Asprey makes similarly dubious claims for his Bulletproof Coffee, which is advertised to be free of mycotoxins, which are bad, because woo.*
However, this either misunderstands or deliberately obscures the science. To understand how, let's take a closer look. An unroasted coffee bean contains roughly 300 volatile organic compounds. If you think back to your last chemistry class (I know, it's probably been a while), if something is subjected to sufficient heat, it doesn't only undergo physical changes; it undergoes chemical changes as well. Using a raw coffee bean as our baseline, then, there'd appear to be some merit in The Healthy Bean's claim. But once subjected to nothing more than heat, those 300 compounds interact with each other to form over a thousand new compounds in varying proportions. Those compounds are what gives coffee its flavor and its healthful properties, all without additives or pseudoscientific trickery.
What does freshness have to do with this? Because several of those natural compounds are volatile and/or water soluble, factors like the passage of time and exposure to moisture or oxygen means that they lose potency or break down. The longer your coffee sits, the less of those compounds are present. Letting coffee sit, especially once it's been ground, robs it of the benefits you'd get from naturally-occurring compounds brought out by a minimum of human intervention. In other words, as long as your coffee is fresh, it'll deliver quite a punch on its own with no add-ons or trickery needed. *
That's not to say mycotoxins don't exist, but the routine washing, roasting, and processing of beans results in ~0.5% of safe levels per cup of coffee. "In other words," says Gizmodo's Brent Rose, "you could drink 199 cups of coffee in a day and still be under the safe limit for mycotoxins. Further, mycotoxins are everywhere, including human breast milk, and a lot of the meats Asprey recommends in his own Bulletproof Diet."