Not everyone is a rat, so in addition to all this rodent research, there are many human studies. Blueberries have been reported to lower blood pressure after eight weeks of daily ingestion. Kids have been found to do better on cognitive tests after eating blueberries. In small trials, people who drank blueberry juice reported reduced depressive symptoms and were found to have improved blood-sugar levels and improvements in recalling words. Older adults who ate two daily cups of blueberries reportedly saw improvements in mobility.

Is this all real? How did all this research come to be? Aren’t there serious diseases that are chronically underfunded in terms of research? Why are we so heavily invested in blueberries?

On a bleak December day in New Hampshire in 2015, Diane McKay took the stage to explain some of this. She’s a scientist in the Antioxidants Research Laboratory at the Tufts University USDA Human-Nutrition Research Center on Aging—which is, it turns out, the origin and epicenter of much of the blueberry work. That day she was addressing industry leaders at the New England Vegetable and Fruit Conference. Her talk was called “Superfruit! Understanding the Health Benefits of Blueberries.”

“The term ‘superfruit’ means different things to different people,” she began. “In marketing, it’s used to advertise a product that has a high level of antioxidant activity. In scientific research, the term is virtually meaningless.”

She explained that claims to superfruit status do often involve antioxidants, the compounds that are believed to minimize the effects of oxidative stress on the body. That is, they negate the negative byproducts of metabolism. The berries aren’t just okay, they’re heroic. They fight evil.

But the measurements are easily manipulated. Various antioxidants can be measured in various ways, and invariably some test will land a given fruit near the top of a rank list. This has led to something like the epidemic of participation trophies among child athletics: Everyone’s a superfruit! McKay advised that the term superfruit “should be used with caution, as it may send the wrong message to consumers, implying they should eat less of all other fruits.”

But if any fruit is deserving of superfruit status, she concluded, it actually may be the blueberry—at least according to the amount of research supporting their intake. Is it really that blueberries are especially super, or that there's just a lot of research on them?

When I reached out to McKay, she directed me to someone who knows even more about blueberries: her colleague, Barbara Shukitt-Hale. Twenty years ago, Shukitt-Hale was drawn into the blueberry game by chance. An experimental psychologist by training, her Boston lab happened to be next door to that of James Joseph, the Tufts scientist credited with popularizing the idea that variously colored fruits have various health benefits.