Quinoa may deliver a complete protein—all of the amino acids you require—in a compact package, but rice and beans together actually do better. And like goji berries, blueberries and strawberries are packed with phytochemicals. The only problem is that lacking an exotic back story, food marketers can’t wring as exorbitant a markup from these staples: The domestic blueberry, for example, is periodically (and justifiably) marketed as a superfood, and in 2012, products featuring blueberries as a primary ingredient saw their sales nearly quadruple. But they only raked in $3.5 million—less than 2 percent of açaí-based product sales.
Tom Philpott, "Are Quinoa, Chia Seeds, and other ‘Superfoods’ a Scam?" (from Mother Jones)
Also worth highlighting is this section:
“Worse than superfoods’ origin myths, though, are their effects on the people in their native regions. In 2009, at the height of the açaí berry hype, Bloomberg News reported that the fruit’s wholesale price had jumped 60-fold since the early 2000s, pricing the Amazonian villagers who rely on it out of the market. In the Andes, where quinoa has been cultivated since the time of the Incas, price spikes have turned a one-time staple into a luxury, and quinoa monocrops are crowding out the more sustainable traditional methods.” (emphasis mine)
So not only are the markets for “superfoods” putting the foods out of reach of the people who relied on them as a dietary staple, but there are foods easily accessible to us that deliver all the nutrition at a fraction of the cost, both to our grocery bill and to the social/environmental toll.