Over the past decade, blueberries have become big business in the U.S. In 1998, the Oregon blueberry harvest was 17 million pounds. By 2013, blueberry production had catapulted to 90 million pounds, on track to reach 150 million over the next five years. Blueberries are certainly  delicious and nutritious, but how much of the Pacific Northwest’s $94-billion-a-year industry can be attributed to the humble fruit’s makeover—by dieticians, cookbook authors, and celebrity doctors—into a superfood?

Dozens of diet books with “superfood” in the title have been published over the last decade. Some so-called superfoods are common: Beans, apples, tea, broccoli. There are also the imported “miracle” berries and roots: açaí, goji, maca. More recently, dragonfruit, breadfruit, and mangosteen were declared nutritional miracle foods. The label often leads to a sales bump; in 2011, the top-selling superfruits brought in more than $205 million. That’s a lot of money spent on nutrient-rich foods that flaunt a label with no official definition.

Are some fruits and vegetable really far superior to the rest? The answer depends on who you ask. Marion Nestle, the author of What to Eat and a professor of nutrition at New York University, told the Washington Post that she doesn’t believe in superfoods. On her blog, Nestle denounced the MonaVie brand that was selling acai juice for $40 a bottle in 2009. “The bottom line: all juices have antioxidants and most are a lot cheaper than MonaVie,” wrote Nestle.

Registered dietician Andy Bellatti agrees that the superfoods label is all about marketing.

“The field of nutrition is primed for these gimmicks because manufacturers know there are a lot of people looking for silver bullets,” says Bellatti. “The term ‘superfood’ as we know it today is silly because it is basically code for ‘grown 15,000 miles away in a remote mountain range and sold at a premium.’ As far as I am concerned, all whole, minimally processed, plant-based foods are superfoods. Are goji berries healthy? Sure. So is an orange.”

The origin of the superfoods label is as murky as the scientific evidence for their nutritional superiority. The label’s first use has most often been attributed to Michael Van Straten, an alternative medicine practitioner and author of Superfoods, an out-of-print cookbook from 1990. Others point to SuperFoods Rx: Fourteen Foods That Will Change Your Life, a 2003 best-selling book by Dr. Steven Pratt.

A recent article in Slate chronicled how, in the early 20th century, the United Fruit Co. transformed the banana into a weight-loss promoting superfruit through relentless marketing. The bananas and milk diet might have gone the way of flapper dresses, but is that fad diet really so different than drinking a daily goji berry smoothie?

Like the “natural” label, the superfoods designation is unregulated, meaning the label can be slapped onto just about any product. Indeed, there is no official or legal definition of superfoods. In 2007 the European Union (EU) banned the use of superfood on product labels for just this reason. Now, foods can only sport that label there if sellers can provide a specific, authorized health claim that explains to consumers exactly how the product can benefit their health.

In the U.S., where the label remains unregulated, food marketers’ efforts to stay ahead of the curve verge on comical. In anticipation that kale chips would jump the shark, one snack food company recently debuted a new line of chips made from purple corn, which they claimed had more “antioxidant power than blueberries, acai berries, and pomegranate juice.” And while this may be true, it might not mean what some consumers think it does.

Ten years ago, sales of acai berry juice skyrocketed, mostly due to claims that the tiny purple fruit from South America contains impressively high antioxidant levels. And yet, in 2012, the anti-aging and disease-fighting benefits of antioxidants, particularly in supplement form, were called into question. In a surprising turn of events, some nutritional intervention trials have found that certain antioxidants have no obvious effect in preventing certain cancers, and in some cases, can actually aggravate them. “Blueberries best be eaten [sic] because they taste good, not because their consumption will lead to less cancer,” writes Nobel Laureate Professor James Watson in a controversial paper published by The Royal Society.

None of that stopped the demand for acai products. In 2013, Sambazon, the Southern California-based company credited with popularizing acai drinks in the U.S., was worth over $100 million in retail sales. Nor did it stop exaggerated health claims by sneaky diet profiteers.

At the same time, the popularity–and sales–of superfoods have benefited from the support of some big names. Dr. Mark Hyman, Director of the Cleveland Clinic Center of Functional Medicine and author of eight best-selling books on diet and nutrition, views the superfoods label in a positive light.

“Plants are filled with phytochemicals that have profound biologic effects,” he told Civil Eats. “‘Superfood’ is a new way to talk about the healing [power] in nutrient-dense food that goes beyond vitamins, minerals, fats, carbohydrates, and protein.”

Certain foods, especially those with organic labels, benefit from a “health halo,” according to a 2013 study by researchers at the Cornell University Food and Brand Lab. In consumer trials, consumers credit these foods with more nutrients and better flavor, in turn leading individuals to report a willingness to pay higher prices for such foods. Brian Wansink, Ph.D and director of the Food and Brand Lab, says that the apparent halo around superfoods may also be misleading  for other reasons too.

“Blueberry sales certainly do benefit from functional scientific claims, but the ‘health halo’ effect becomes dangerous when foods that are less clearly healthy for you are associated with something considered healthy–like muffins made with organic flour,” he says.

Most experts seem to point to the idea that fruits and vegetables–super or not–are what constitute a healthy diet. “If you genuinely enjoy mangosteen, by all means eat some,” says Bellatti. “But don’t fool yourself into thinking that a mangosteen is superior to a blackberry or a pear.”