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Dark chocolate is now a health food. Here’s how that happened.

The Mars company has sponsored hundreds of scientific studies to show cocoa is good for you.

A year after James Cadbury, the 30-something great-great-great-grandson of the British chocolatier John Cadbury, launched his luxury cocoa startup in 2016, he introduced an avocado chocolate bar.

Cadbury Jr.’s newest confection loaded just about every buzzy health trend into a fresh green-and-white package: vegan, ethically sourced, organic dark chocolate and creamy, superfood avocado. The company promised to deliver the nutrition of avocados — in a chocolate bar. Journalists were dazzled.

Love Cocoa

Wait, what? Make no mistake: This vegan avocado chocolate bar is candy. With nearly 600 calories and 43 grams of fat per 100-gram serving, the bar packs more fat and calories than Cadbury Dairy Milk, and just a little less sugar.

So how in the world could a chocolate bar be convincingly sold as a health food? You can thank a decades-long effort by the chocolate industry.

Over the past 30 years, food companies like Nestlé, Mars, Barry Callebaut, and Hershey’s — among the world’s biggest producers of chocolate — have poured millions of dollars into scientific studies and research grants that support cocoa science.

Industry funding in nutrition science is not uncommon — grape juice makers and walnut growers sponsor studies showing these foods improve driving performance or cut diabetes risk. But Big Chocolate’s foray into nutrition research is a great case study in how industry can steer the scientific agenda — and some of the best minds in academia — toward studies that will ultimately benefit their bottom line, and not necessarily public health.

Here at Vox, we examined 100 Mars-funded health studies, and found they overwhelmingly drew glowing conclusions about cocoa and chocolate — promoting everything from chocolate’s heart health benefits to cocoa’s ability to fight disease. This research — and the media hype it inevitably attracts — has yielded a clear shift in the public perception of the products.

“Mars and [other chocolate companies] made a conscious decision to invest in science to transform the image of their product from a treat to a health food,” said New York University nutrition researcher Marion Nestle (no relation to the chocolate maker). “You can now sit there with your [chocolate bar] and say I’m getting my flavonoids.”

Amid a historic obesity epidemic, this new niche of nutrition science has helped build a solid aura of health around chocolate — and grow consumer demand. Chocolate retail sales in the US have risen from $14.2 billion in 2007 to $18.9 billion in 2017, the market research group Euromonitor International found, at a time when candy sales overall have been waning.

Big Chocolate’s investment in health science was a marketing masterstroke, catapulting dark chocolate into the superfood realm along with red wine, blueberries, and avocados — and helping to sell more candy.

Health-conscious consumers now increasingly seek out “premium” dark and gourmet chocolate, Euromonitor found, the success of which “stems partially from the health benefits associated with a higher cocoa content.”

But despite the industry effort to date, cocoa still has never been proven to carry any long-term health benefits. And when it’s delivered with a big dose of fat and sugar, any potential health perks are very quickly outweighed by chocolate’s potential harm to the waistline.

That’s something consumers all too easily forget in the face of delights like the vegan avocado chocolate bar.

How Mars helped turn chocolate into a heart healthy snack

In 1982, Mars Inc. — the company that has brought us M&M's, Snickers, and Twix — established the Mars Center for Cocoa Health Science in Brazil to study, in part, the biology of cocoa and its impact on human health.

Since then, mainly through the company’s scientific arm Mars Symbioscience, established in 2005, it has flooded journals with more than 140 peer-reviewed scientific papers.

Mars’ initial focus on studying the health benefits of chocolate has shifted to studying a group of compounds called flavanols. Flavanols are micronutrients found in many fruits and vegetables, including cocoa. These “phyto” — or plant-derived — chemicals have antioxidant properties and seem to promote vascular health (more on that later). Researchers suspected flavanols might be one of the reasons fruits and vegetables are so good for the body.

Companies selling flavanol-rich products have been on a quest to find out what flavanols do — and how they can be hyped. One of the earliest Mars papers, published in the Lancet, demonstrated that chocolate was a great source, even compared to flavanol-rich tea. “As a result,” the candy company claims on its website, “Mars started a research program to identify and isolate flavanols from cocoa, and to use these cocoa flavanols in the study of human health benefits.”

In addition to the science Mars generates, the company has also endowed a chair in nutrition science at the University of California Davis, and sponsored research conferences that focus on subjects like “The Potential Use of Cocoa Flavanols in Preventing Cardiac and Renal Disease.”

To find out what kind of conclusions Mars-sponsored studies come to, Vox searched the health literature and identified 100 original cocoa health studies funded or supported by the chocolate maker over the past two decades. (We also found dozens more Mars-supported cocoa studies that weren’t health-related and systematic reviews of the research evidence.)

Among the findings in the Mars-sponsored health studies: Regularly eating cocoa flavanols could boost mood and cognitive performance, dark chocolate improves blood flow, cocoa might be useful for treating immune disorders, and both cocoa powder and dark chocolate can have a “favorable effect” on cardiovascular disease risk. The institutions that received Mars support stretch across the US and all over the world — from UC Davis to Harvard and Georgetown universities, from Heinrich Heine University in Düsseldorf, Germany, to the University of Buenos Aires, Argentina.

All told, nearly every one of the studies came to positive and favorable conclusions about cocoa or chocolate.

Javier Zarracina/Vox

Such overwhelmingly positive findings suggest this area of industry-funded nutrition science may be biased. “By spending a lot of money on one topic but not another, [it] can sort of create a publication bias,” said Richard Bazinet, a University of Toronto nutrition researcher. In other words, companies pouring money into studying a certain food and a specific set of questions about that food pushes the research agenda in a particular direction — one that the food companies favor. (In the Cochrane review of chocolate research, studies funded by companies with a commercial interest in the results tended to report effects on blood pressure that were larger than the independent studies, “indicating possible bias.”)

Tying up researchers’ hours on cocoa — which may or may not have marginal health benefits — also means other, more important studies aren’t getting done. “Mars is controlling the research agenda in its corporate self-interest,” said NYU’s Nestle. “But think about the kinds of projects that might get done if an equivalent amount of money was available for investigator-initiated research that might have nothing at all to do with selling food products and everything to do with promoting health.”

Bias can seep into research in other ways, as we explained in a story about industry-funded nutrition research. Industry may chose to fund researchers with favorable views about their products, and researchers may consciously or unconsciously tweak the design of their studies or their interpretation of results to arrive at more positive conclusions.

Mars would not disclose how much it’s invested in cocoa science, saying it is a private company, and this information is not publicly available. Vox also asked Mars to comment on the concerns of independent researchers, and it responded: “We are always clear that chocolate is a treat, not a snack, food, or meal replacement, and market our products accordingly,” adding, “we do not translate or communicate the outcomes of our cocoa flavanol research program in the context of chocolate.”

Its cocoa flavanol research instead supports its CocoaVia line of supplements and bars that are marketed as health foods, a spokesperson added. CocoaVia’s products, which “promote healthy blood flow from head to toe,” have been dinged by the Advertising Self-Regulatory Council for these health claims.

Mars is certainly not alone in the chocolate industry’s effort to steer the academic research agenda. The Swiss cocoa producer Barry Callebaut, along with Hershey and Nestlé, has also funded many studies showing cocoa is healthy. Like Mars, Nestlé has been sponsoring “Nestlé chairs” at research institutions, such as the Swiss École polytechnique fédérale de Lausanne, to study energy metabolism and neurodevelopment. Nestlé has veto power over who gets the chair appointment.

How the media feeds chocolate hype

The resulting cocoa and chocolate studies are catnip for journalists, who often write about them under headlines like “Good news for chocolate lovers: The more you eat, the lower your risk of heart disease,” or simply “Chocolate is good for you.”

In one example, a Columbia University researcher, Adam Brickman, led a Mars-funded study, looking at how cocoa flavanols might affect the dentate gyrus, a region of the brain whose deterioration with age is associated with memory decline. His paper concluded that flavanols may improve dentate gyrus function, according to specific cognitive ability tests.

But the university public relations team and the media hyped the findings, and turned a small flavanol supplement study into a big chocolate study.

Columbia University’s newsroom touted the research as demonstrating that “dietary flavanols reverse age-related memory decline” — even though the study was small and preliminary. The research was then picked up by media outlets, including the New York Times, which trumpeted chocolate as a memory aid.

“We [were] very careful about not referring to [the cocoa flavanols] as chocolate,” said Brickman. “Nothing was more upsetting than seeing the headlines along the lines of ‘eating chocolate cures Alzheimer’s,’ which was not what our study was about.”

Fawning cocoa coverage is so pervasive, one journalist even created a bad chocolate study, suggesting the candy promotes weight loss. His goal was to fool the media into picking it up and make a point about how easy it is to do so. (It worked.)

So is chocolate good for your health? In a word: no.

Cocoa’s effects on blood flow have never been directly linked to a lowered risk of cardiovascular events.

In our review of cocoa health science published to date, we found that the most compelling (and best-studied) effect has to do with cocoa’s effects on blood pressure.

There’s promising evidence showing cocoa flavanols can increase the synthesis of nitric oxide in the blood vessels, which boosts blood flow (or vasodilation) and reduces blood pressure. Lower blood pressure has been linked with a lower risk of cardiovascular events like heart attack, stroke, and cardiovascular mortality. According to a Cochrane systematic review of the cocoa research on blood pressure, flavanol-rich chocolate and cocoa products “cause a small (2 mmHg) blood pressure-lowering effect in mainly healthy adults in the short term.”

Chocolate’s heart health benefits are extremely appealing at a time when heart disease is still the leading cause of death in America. When researchers have run big, high-quality observational studies, following many people’s diets, they’ve found associations between chocolate eating and a lower risk of cardiovascular problems — and many of these studies weren’t funded by the industry.

Here’s the hitch, though: Cocoa’s effects on blood flow have never been directly linked to a lowered risk of cardiovascular events. So cocoa may impact blood pressure in the short term, but it’s never been proven to reduce the risk of heart disease or heart attacks. And observational studies can only show correlations between phenomena — not that eating chocolate caused the reductions in heart problems. It may be that chocolate eaters are wealthier or have other characteristics, aside from their chocolate-eating habit, that protect them from disease.

What’s more, while fresh cacao beans are rich in flavanols, the nutrient can get destroyed during chocolate processing, so most candy bars don’t deliver the potentially blood-boosting stuff. (Mars now markets its CocoaVia products as being made with “gently handled” cocoa beans that “preserve and protect the cocoa flavanols inside.”)

Researchers are now trying to sort out whether the promising smaller trials and observational studies on cocoa and heart health translate into fewer clinical events like heart attacks through a major randomized controlled trial called COSMOS, run by researchers at Brigham and Women’s Hospital, an affiliate of Harvard Medical School, and the Fred Hutchinson Cancer Research Center in Seattle.

Interestingly, that study focuses on the effects of cocoa supplements, not chocolate, since supplements are a better flavanol delivery vehicle. COSMOS and its ancillary studies also happen to be funded by Mars Symbioscience, as well as Pfizer Inc. and the National Institutes of Health — the culmination of its decades-long investment in searching for chocolate’s health attributes.

Chocolate is just one of America’s favorite sugar delivery devices

Mars frames its foray into cocoa science as an effort to better understand the prized cacao fruit. Outside observers view it as a marketing ploy.

Michael Coe, a Yale University chocolate historian and co-author of the book The True History of Chocolate, views Big Candy’s investment in cocoa science as an effort to counterbalance the negative publicity that came out of the fair trade movement, which highlighted the cocoa industry’s dependence on child and slave labor, as well as the evidence suggesting the obesity epidemic is being driven by sugar.

In 2015, Americans’ consumption of added sugars was 358 calories per day, or about 94 grams, up from 235 calories per day in 1977-’78. There’s a mountain of research on all the ways a sugar-heavy diet can harm our health: Increased risks of obesity, Type 2 diabetes, tooth decay, and heart disease are just some of the most well-established examples.

Pie, cake, cookies, and candies — including chocolate — are still some of the leading sources of added sugar in the American diet. The Euromonitor data shows Americans will consume nearly 1.4 million metric tons of chocolate sold through retail in 2017. That’s about 30 Titanics’ worth of chocolate, or 9 pounds of chocolate per American. (Holidays are always big for the chocolate industry, with Halloween representing peak chocolate.)

“[Funding cocoa science] is quite clearly a sales thing to sell more chocolate because [the studies] suggest it’s not all that bad for you,” Coe said. “Chocolate companies can say they have scientifically proven that chocolate will lower your blood pressure, keep you from heart attacks.”

Their investment appears to have paid off. “Premium chocolate,” like the vegan dark chocolate avocado bar, is helping drive growth in the chocolate market, Euromonitor found in an analysis of the US chocolate industry. Americans are increasingly looking for “healthy indulgences” as they become more aware of nutrition — and turning to snack bars like Kind, or dark chocolate with fruits and nuts, for their fix.

“I don’t want to be cynical — a lot of their science is good; it’s put in peer-reviewed journals,” Coe added. “But just keep in mind that too much of anything is not really good. If you’re hooked on chocolate, you’re hooked on sugar.”

Industry funding can warp our perceptions of chocolate

When you look at industry-funded studies, one thing becomes clear: They tend to focus on the health attributes of cocoa: its impact on cardiovascular health or cognitive function. But they don’t address the role the cocoa delivery mechanism — sugary chocolate — may play in obesity. Most Mars and Hershey chocolates also contain very small amounts of the cocoa that supposedly promotes heart health — along with lots of fat, sugar, and calories.

“Dark chocolate probably has some beneficial properties to it,” said Salt Sugar Fat author Michael Moss, “but generally you have to eat so much of it to get any benefit that it’s kind of daunting, or something else in the product counteracts the benefits. In the case of chocolate, it’s probably going to be sugar.”

The chocolate-industrial-research complex also distracts us from really important avenues of nutrition research, like better understanding what in our food may be contributing to the parallel obesity and diabetes epidemics, and how we can solve vexing problems like malnutrition. Chocolate certainly isn’t the solution here.

“It’s a great business to fund studies whose conclusions provide candy makers with the ability to promote people’s favorite foods as healthful,” said obesity doctor Yoni Freedhoff, “and while maybe not everyone will believe their candy bars are the ticket to health, I bet plenty, consciously or unconsciously will think [chocolates are] not as bad for them as they thought and buy them more often.”

“The idea that dark chocolate is healthy has worked its way into the mainstream psyche,” said NYU food historian Amy Bentley, adding that even the very restrictive Paleo dieters sanction dark chocolate because of its “numerous health benefits.”

There is a case for high-quality cocoa science

Some researchers argue that we really do need high-quality studies on nutrition, even if they are funded by Big Chocolate. Referring to the Mars-funded COSMOS trial, Stanford University health researcher John Ioannidis said he thought the effort was not a waste since this is a health question people care about.

“We have already spent billions of dollars and tens of thousands of studies trying to address [nutrition] questions with observational data and small, biased trials that really get us nowhere. At least these large trials can be definitive,” he said, and put all the noise from smaller studies to rest. (He did add, “If I have to bet, I believe that these trials will almost always give conclusively negative results regarding major health benefits.”)

Bigger, better studies may find that cocoa is in fact a health elixir, so we should keep doing them. “It’s important to understand whether something as simple and low-risk as increasing a nutrient in the diet could also have health benefits,” said JoAnn Manson, a Harvard nutrition researcher. “[Cocoa] has looked promising in small-scale randomized controlled trials and in observational studies, so it’s worth moving now to more conclusive and large-scale randomized controlled trials.”

Manson also noted that she’ll be publishing the results of the COSMOS randomized trial regardless of the outcomes — whether they prove cocoa is a health food or not — which would help combat the kind of publication bias Bazinet was worried about.

Perhaps the COSMOS trial will end the debate about cocoa’s true effects on the body. Until then, it’s important to keep in mind that there’s rarely clear evidence that specific foods have miraculous health effects. Instead, healthy eating patterns seem to matter much more than how much of any one food you consume. And a diet heavy in chocolate is a diet heavy in sugar, calories, and fat.

Editor: Eliza Barclay
Graphics: Javier Zarracina
Research: Ruairí Arrieta-Kenna
Copy editing: Tanya Pai


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