Goji (wolfberry) is one of the most recent fruits to be hyped as a "superfood," alongside acai, pomegranate, cranberry, blueberry and many others. These foods are supposedly packed with beneficial chemicals including antioxidants, vitamins, minerals, fiber and other so called "phytochemicals," an incredibly irritating neologism of the words "plant" and "chemical."
This trend annoys me not only because there is often really lousy science backing up the claims that individual chemicals (out of tens of thousands of unknowns) in these foods are beneficial for human health but also that it goads people into taking concentrated pills and extracts that supposedly isolate and concentrate what's best about our food. This magical reductionism seems uniquely American to me and completely overestimates out understanding of exactly what in these foods is good for us.
Similarly, I've consistently heard that a lot of nutrition scientists and government regulatory agencies have stuck with outdated nutrition assays (e.g. antioxidant assays) because 1) they already know how to do them and 2) they want to be able to compare new results to old results.
I saw a great presentation by the Cornell food scientist Rui Hai Liu a few months ago where he described his new "cellular antioxidant activity" assay. He described how his new assay measured the antioxidant activity of fruit chemicals much more accurately than older methods by considering the ways that these chemicals actually get into your cells and protect you from normal oxidative stresses that contribute to diseases such as cancer. One of the most effective antioxidant extracts turned out to be apple juice! Conventional wisdom never would have guessed this. It really goes to show how little we actually understand what's in our food and how it affects our health.
I ordinarily wish that Michael Pollan would keep his poorly-informed opinions to himself, but I agree with him when he tells people to stop stressing out so much about optimizing their nutrition and just eat a diverse diet, mostly veggies.