Reference
Desideri G, Kwik-Uribe C, Grassi D, et al. Benefits in cognitive function, blood pressure, and insulin resistance through cocoa flavanol consumption in elderly subjects with mild cognitive impairment: the Cocoa, Cognition, and Aging (CoCoA) study. Hypertension. 2012;60(3):794-801.
Design
A double-blind, parallel-arm study in which participants were randomized into 3 groups to consume a daily cocoa drink of differing flavanol content.
Participants
90 elderly individuals with mild cognitive impairment (MCI) diagnosed according to the revised Petersen criteria. Cognitive function was assessed by Mini Mental State Examination, Trail Making Tests A and B, and verbal fluency test.
Study Medication and Dosage
After a 1-week run-in period, participants were randomly assigned to 1 of 3 groups, each of which drank a daily cocoa drink of differing flavanol strength. The cocoa drinks, though seemingly identical, varied significantly in flavanol content. Two drinks contained relatively high levels, one with ~990 mg (high flavanols) and the other with ~520 mg (intermediate flavanols) per serving. The third group drank ~45 mg (low flavanols) per serving drink. These drinks were consumed once daily for 8 weeks. The drinks that had high and intermediate flavanol content were prepared using CocoaPro made by Mars Inc. The low-flavanol drink was made with a highly processed, alkalized cocoa powder.
Outcome Measures
Cognitive testing was performed at baseline and after 8 weeks using a combination of 4 standardized tests: The Mini Mental State Examination (MMSE), Trail Making Test (TMT) A, TMT B, and a verbal fluency test. Blood pressure, serum glucose, insulin resistance, and lipid peroxidation were also tracked.
Key Findings
After 8 weeks, participants consuming the high and intermediate flavanol cocoa products did significantly better on both trail-making tests; had significantly better verbal fluency scores; and had significantly reduced insulin resistance, blood pressure, blood glucose, and levels of lipid peroxidation. None of these test results changed in participants who consumed the low-flavanol cocoa.
Practice Implications
This may be the first study to demonstrate cognitive benefits from chocolate. Earlier studies have reported cognitive benefits from flavanols sourced from other food sources, in particular Krikorian’s trial that found Concord grape juice improved cognitive function in 2010.1
These current data suggest target doses for daily flavanol consumption. Benefits are significant at about 500 mg/day and increase with higher doses. Low doses have no apparent benefit.
A related study on chocolate flavanol's effect on cognition and mood was published in May 2013. This was shorter (30-day) trial using lower doses of flavanols (500, 250 and 0 mg/day). “After 30 days, the high dose of treatment significantly increased self-rated calmness and contentedness relative to placebo,” the authors write. “This randomized controlled trial is perhaps the first to demonstrate the positive effects of cocoa polyphenols on mood in healthy participants.”2 Cognition was unaffected by the chocolate treatment in this study. Since this study used a lower dose for a shorter time, perhaps it is not surprising that there was less effect.
While chocolate offers potential benefits, the difficulty in obtaining chocolate products with high flavanol content limits our ability to use it effectively.
Chocolate flavanols appear to have potential in treating both cognitive decline and mood. The problem though is how to provide patients with an adequate daily dose of these flavanols, ideally in the 1 gram per day range.
Even though the research on chocolate demonstrates benefit from consuming the right chocolate, finding these high flavanol chocolates remains difficult. The flavanols that occur naturally in cacao beans are easily destroyed during chocolate manufacturing. We cannot be assured that the same benefits written about in these and other studies will occur in patients who consume any chocolate.
Langer et al reported in 2011 that they had tested 14 commercially available chocolate bars. Nonfat cocoa solids (NFCS) were somewhat correlated with total flavanols, so we can say that dark chocolates contain higher total flavanols than milk or white chocolate. Among the dark chocolates, though, there was almost a 7-fold variation in content. The integrity of these chemicals “often suffer[s] in the manufacturing of chocolate, chiefly due to oxidation and alkalinization.”
While “high % NFCS is being used commercially to reflect chocolate quality” it remains a weak measure of the actual flavanol content.3
Hollenberg and Fisher sum this up in a 2007 editorial in the journal Circulation:
"All cocoa is created flavanol-rich. It is primarily the processing of natural cocoa solids into cocoa powder or into confectionary chocolate that determines whether a final product is flavanol-rich or -poor. Because flavanols are bitter, manufacturers have often treated natural cocoa with processing techniques that necessarily destroy the flavanols as they enrich flavor and improve consistency.
"The use of the term 'dark chocolate' is misleading: There is nothing about the color of the chocolate that will tell you the flavanol content. One of the key places in the manufacturing chain where significant loss of flavanols occurs, after fermentation, is an alkalization step called dutching.”4
In other words, most labels on chocolate products reveal little about the relative health benefits of their contents. Not everyone agrees with this though.
Miller et al from the Hershey Company suggest that flavanol content can be approximated by the general category of chocolate products. They provide a list going from highest to lowest flavanol content: cocoa powder > baking chocolate > dark chocolate = baking chips > milk chocolate > chocolate syrup.5
This is hardly reassuring though as the low-flavanol experimental group in the current Desideri study consumed a drink made from commercial cocoa powder, which had a fraction of the flavanols as in the other drinks.
There is no easy way to tell a patient which chocolate to eat. The percentage of chocolate solids typically reported does not allow us to compare flavanol content.
The high-flavanol cocoa used in the current Desideri study was manufactured by Mars Inc. and is called CocoaPro. We know of only 3 companies using this chocolate in their products: CocoaVia® (250 mg of cocoa flavanols per serving), Goodnessknows® (200 mg flavanols per serving), Dove® Dark Chocolate (flavanols vary by product).
Many of the clinical trials conducted in Europe have used a different chocolate, Acticoa made by Barry Callebaut Chocolates. We have not yet found a source for this chocolate in the United States. Thus while chocolate offers potential benefits, at this time, the difficulty in obtaining chocolate products with high flavanol content limits our ability to use it effectively.
