Is dark chocolate good for your heart? We myth-bust bogus health food claims.

Blueberries are not a superfood. Chocolate is not good for you. Mango is not a cure-all.

When you grab a bag of Barkthins, a product billed as “snacking chocolate” that is made of slivers of pretzels or nuts in a light coating of dark chocolate, you won’t see anything about health on the label. The U.S. government won’t allow it, but the nutrition claim is no longer necessary. Among consumers, dark chocolate might forever have a halo of good health.

“The idea that dark chocolate is a health food is pervasive in society. Everybody believes that,” says food policy expert Marion Nestle (no relation to the company), professor emeritus at New York University and former Chronicle columnist.

Chocolate is only one example. At

“The idea that dark chocolate is a health food is pervasive in society. Everybody believes that.”

Marion Nestle, professor emeritus at New York University and former Chronicle columnist

the checkout line, magazine headlines scream that chia seeds will detox your body and white beans will ease joint pain, even though few such claims are backed by real science. Nestle has long raised the alarm about how nutrition claims in advertising, news articles and labels — at least when the U.S. Food and Drug Administration allows it — are often based on industry-funded studies. Her latest book, “Unsavory Truth,” is devoted to the subject, and new examples crop up so often that she devotes a weekly post to them in her Food Politics blog.

“There must be something about the way that humans are hardwired,” says Nestle. “It’s this degree of magical thinking that feeds into the way human psychology works, and the food companies that do that kind of research know this very well.”

The example of chocolate goes back decades. In the 1980s, candy companies like Mars began sponsoring research they said demonstrated a connection between chocolate and heart health, and started putting the claim on certain products before the government cracked down on it, saying the claims were unproven. Even though the idea was faulty — for one, the healthful components in raw chocolate tend to be destroyed in the roasting process — we all bought it. Who doesn’t want to feel righteous about eating candy?

One of Nestle’s recent favorites is a study that claimed to show how drinking beer can help prevent Alzheimer’s. Another one looked at how regularly chewing sugar-free gum could improve memory.

“I think the stuff is hilarious. You can’t make it up,” she says.

The obvious problem with nutrition studies funded by a specific industry group or company is that they undermine the scientific process because they set out to prove the nutritional benefits of a particular food for marketing reasons.

But Nestle is also critical of the way such studies promote a message contrary to most nutrition advice: that certain foods are mega-healthy while others are not. Ads that promote blueberries or almonds may be accurate when they describe the fruit or nut’s health-promoting qualities, but distract from the reality that other foods contain similar amounts of antioxidants or vitamins.

“The basis of healthy diets is eating a wide variety of healthy foods of all types,” Nestle said at a recent event at UC San Francisco. “All fruits and vegetables have benefits. I don’t believe in superfoods.”

Pomegranates are an example Nestle has taken on for years (originally in The Chronicle). The California company POM Wonderful has spent $35 million on research, she reports, to demonstrate all the potential health benefits you can get from drinking its juice. At one point the company claimed its product would help you cheat death in ads (which were quashed by the Federal Trade Commission). Pomegranates do contain lots of antioxidants, but so do many other fruits.

Such promotion of a constantly changing roster of superfoods can give people nutritional anxiety.

“I tell people to give themselves permission to eat what they like. Just try to control the quantity,” she says. “It just makes me cry that people are so anxious about something that is so easily pleasurable.”

In a statement, a Mars spokeswoman responded, “We believe that chocolate is a treat, not a health food. Mars has been doing research on cocoa — from plant health to human health for over 25 years and we have not undertaken a study to investigate the health benefits of chocolate for over a decade.”

Mars does continue to conduct research on the health benefits of cocoa flavanols for its CocoaVia dietary supplements, which do contain the potentially healthy components that are usually destroyed in roasting. The product boasts that it supports heart and brain health “by promoting healthy blood flow,” a claim “supported by 20 years of science.”

Science, of course, that was paid for by Mars itself.