Most of us would gladly eat more chocolate if we found out it had brain benefits. In 2012, we reported on a study in the journal Hypertension showing that older people with mild cognitive impairment (MCI) benefited by drinking a cocoa beverage rich in flavanols, a key subclass of flavonoid compounds found in cocoa beans—the basis of chocolate—as well as in red wine, grape juice, tea, berries, and many other plant foods. (MCI is characterized by memory problems more serious than those seen with normal aging, but less severe than those of dementia.)
Not only did the participants’ blood sugar, blood pressure, and oxidative stress levels improve over eight weeks, they also did better on a series of memory, verbal fluency, and other cognition tests. The study used a specially formulated cocoa extract produced by Mars Inc., which funded the research and sells a commercial version of the product, called CocoaVia. Since then, several other studies (described below) have looked at the relationship between cognition and chocolate (which consists of cocoa powder, cocoa butter, and other ingredients) or cocoa (the chocolate component that contains the flavanols).
It’s important to note up front that critics have questioned the objectivity of research funded by Mars, which has produced some 140 scientific papers. Most of this industry research (from other chocolate manufacturers as well, including Hershey’s and Nestlé) is positive, suggesting there may be bias in the reporting. Still, despite Big Chocolate’s role, some positive findings published in peer-reviewed journals come from independent scientists and government-funded studies.
A sampler of chocolate research
- A 2017 observational study in Nutrición Hospitalaria assessed the chocolate intake—milk, dark, and total—of older people in Spain, who were then given a brief exam to test their mental status. Those who reported consuming the most chocolate (about an ounce a day, on average)—and dark chocolate, in particular, which is typically richest is flavanols—performed better than those who ate none. A higher intake of dark chocolate was also linked with less likelihood of having MCI. The study, which was not funded by industry, controlled for weight, physical activity, smoking, and other dietary factors such as calories, sugar, and alcohol.
- A 2016 observational study in Appetite included nearly 1,000 people in New York State over a wide age range (23 to 98). Those who reported eating chocolate at least once a week did better on a battery of neuropsychological tests than those who rarely or never ate chocolate. With the exception of one test, the results did not change when the researchers controlled for cardiovascular, lifestyle, and additional dietary factors. The authors, who reported no conflicts of interest, did not differentiate between milk and dark chocolate. Further analysis supported a causal relationship between chocolate intake and better cognition, ruling out the possibility that people with better cognition to begin with simply tended to eat more chocolate.
- A clinical trial from Italy, sponsored by Mars and published in the American Journal of Clinical Nutrition in 2015, included 90 older people with no evidence of cognitive impairment at the start, who were divided into three groups: Each drank a specially formulated cocoa flavanol beverage every day, but with low, medium, or high amounts of cocoa flavanols. After eight weeks, those in the high-flavanol group, and to some extent the medium-flavanol group, did better on tests measuring different aspects of cognitive function, including verbal fluency, compared with those in the low flavanol group—though even the low-flavanol group showed some improvement compared to baseline. The concomitant reduction in insulin resistance, which affects blood sugar control as well as brain function, may help explain the results, the researchers suggested. They concluded that such findings lend more support to the notion that “dietary flavonoids and, specifically, flavanols may play a positive role in maintaining and improving cognitive function, particularly with age.” Note, however, there was no placebo group that received a no-flavanol cocoa beverage.
While such results are promising, not all chocolate studies have found evidence of cognitive benefits. For example, a double-blind, placebo-controlled study of 101 people, published in the American Journal of Clinical Nutrition in 2008, failed to find neuropsychological improvements in those consuming dark chocolate or a cocoa beverage daily for six weeks.
These and other chocolate studies have a number of shortcomings. Many are observational; they rely on self-reports and don’t prove cause and effect. Though researchers control for variables that can affect the results, it’s impossible to account for all of them. As for clinical trials, they tend to be small and short in duration (typically just a few days to a couple of months), so it’s not known if any effects would persist over time; some studies have used just a single dose of chocolate, cocoa, or cocoa flavanols.
It’s also not known what the optimal intake of flavanols would be, since studies have used different amounts: Levels in chocolate vary, depending on the variety of bean, origin, and manufacturing processes. Nor is it known who might benefit most from chocolate in terms of age and cognitive health (for example, those who already have some cognitive decline versus those who are cognitively healthy).
Bear in mind, too, that results from studies using specially formulated cocoa products or other high concentrations of flavanols can’t be extrapolated to people eating chocolate bars that have much lower levels of these compounds.
Is CocoaVia the Best Cocoa Supplement?
CocoaVia is a proprietary cocoa extract, sold by Mars as a dietary supplement. It's touted to "promote healthy blood flow, which supports a healthy heart and brain."
Your brain on chocolate
Several mechanisms have been proposed to explain the possible cognitive benefits of chocolate and its flavanols. For instance, flavanols may promote formation of new blood vessels, improve vascular function by enhancing the body’s supply of nitric oxide, and increase cerebral blood flow.
Supporting this last mechanism is a 2015 study in Psychopharmacology, which used a special brain imaging technique in 18 healthy people, ages 50 to 65, and found that brain blood flow increased within two hours of drinking a high-flavanol cocoa beverage relative to a low-flavanol cocoa beverage, especially in two areas of the brain involved in decision-making. The potential heart-health benefits of chocolate observed in other studies over the years may also be attributed to improvements in blood vessel functioning and increased blood flow (what’s good for the heart is good for the brain, after all).
In addition to flavanols, chocolate contains caffeine and theobromine. Studies suggest that these substances may enhance cognitive functioning and alertness, though theobromine has not been as well studied, and it’s not entirely clear how it affects the nervous system. Some of the benefit may be due to stimulant effects, or possibly due to the substances’ ability to elevate mood, which might enhance cognitive functioning. More research is needed to determine which compounds in chocolate may be beneficial to the brain—several of them may work together synergistically.
As a 2013 review in the British Journal of Clinical Pharmacology noted, “All these properties are of great interest but at present it is not clear when the consumption of cocoa and chocolate should be initiated to generate beneficial effects on age?dependent cognitive decline and neurodegenerative diseases and many studies are still necessary to explore the neuroprotective potential of cocoa and chocolate.”
Whether chocolate can help improve cognitive functioning or prevent its decline is still uncertain—more independent clinical trials, from researchers without a vested interest, are needed. It’s okay, and maybe even beneficial, to eat chocolate, especially dark types, in moderation, if you like it, not because you think it will make you smarter. But we certainly don’t recommend consuming large amounts regularly. First of all, most commercial chocolate bars are more like high-calorie junk food than health food, with about 240 calories and 20 grams of added sugar (5 teaspoons’ worth) per 1.4-ounce serving.
Moreover, not all chocolate or cocoa is rich in flavanols. According to a report from ConsumerLab.com, which was last updated in January and includes 43 cocoa or cocoa-based products, some of the products had very low levels of flavanols (sometimes along with worrisome amounts of the toxic metals cadmium and lead). In general, the darker the chocolate, the more flavanols it has, but this is hard to judge, and the “percent cocoa” listed on some labels is not always a reliable gauge. Cocoa powder that is Dutch- or alkali-processed (as many are) loses much of its flavanol content. To get the most out of cocoa, look for non-alkalized ones.
A better bet for getting a healthy dose of flavanols—and the larger class of flavonoids—is to focus on a healthy diet that includes fruits and vegetables. They have far fewer calories than chocolate and an abundance of vitamins and minerals, along with fiber and other healthy plant compounds.
This article first appeared in the UC Berkeley Wellness Letter.
Also see How to Find the Healthiest Chocolate.
Published May 01, 2018