Whole Plants Versus Pills: The Cases of Curcumin and Quercetin
Herbalists, though we’ve been known to use isolated constituents from plants, often prefer traditional, whole-plant preparations like teas, tinctures, or powders. These “crude” extracts, we often claim, may appear to be less concentrated but are actually more effective than isolated molecules when given by mouth to a living, breathing human being. But is there any evidence to support this claim? If a certain constituent has therapeutic activity, it seems counterintuitive that refining and concentrating it might somehow make it less effective.
The issue, in the end, is one of bioavailability: the ability of medicinal chemicals to reach the target areas in the human body where they can exert their effects. It does us little good to take high doses of molecules that never reach tissue at appreciable concentrations. This, of course, is one of the problems with petri dish research: a given chemical may have an effect on neurons in a lab, but that’s far from a guarantee that it will enter our bloodstream, leave the liver unchanged, cross our blood-brain-barrier, and have the same effects on neurons in our central nervous system.
One of the most famous, and researched, examples comes to us from the traditional Indian spice turmeric (ground rhizome of Curcuma longa). Curcumin and its molecular relatives the curcuminoids are polyphenolic pungent chemicals found in turmeric. They have attracted substantial attention, especially over the last decade, as potential medicinal compounds. But as a recent review article discovered,1 this rarely translates […]