Chocolate & Flavanols

Photo by Olga Valisjeva.

Since Nature Neuroscience published an article Sunday, October 26th (online) about the positive effects of cocoa on memory, I've seen dozens of news stories heralding this finding.

Before people start consuming truckloads of chocolate bars, let's take a closer look at elements of their research.

First, the study wasn't aimed at finding the health benefits of chocolate as much as it was aimed at isolating the role of one region of the brain in memory and one type of memory--episodic.

Specifically, the authors were looking at the dentate gyrus, a region of the hyppocampus that allows neurogenesis or the growth of new brain cells.

In their abstract, their conclusion was focused on the brain region and not the role of the cocoa drink:

"Our findings establish that DG dysfunction is a driver of age-related cognitive decline."

Studies of this part of the brain and their function in memory and new brain cell grown are still very young--measured in years and not even decades.


Second, the cocoa consumed in the study was a special blend high in flavanols: 900 milligrams per day. This is higher than commercially available cocoa powder.  For comparison, the Washington Post noted that an average candy bar contains about 40 mg of flavanols.

Currently, the flavanol content is not clearly found on food labels, as the authors of a 2008 study bemoan. By conducting tests of 20 commercially available samples of cocoa powder, they found a wide variety of flavanol levels.  The flavanol levels ranged from 34.6 mg to 3.9 mg per gram of each cocoa powder sample measured. (Nothing anywhere near the 900 mg level of the Nature study published this week.)

The tests of flavanol levels in commercially available cocoa found that the higher the degree of Dutch processing, the lower the flavanol content.   Natural cocoa is bitter, but removing that bitter taste also removes the beneficial flavanol.

How could a person consume 900 mg of flavanols in available sources of chocolate? That's a lot of candy or a lot of hot cocoa. And the added fat and sugar would outweigh the benefits of the flavanols. There are flavanol supplements emerging on the market, but they are expensive and many don't guarantee a specific flavanol amount in their product.

Third, the data set was extremely small. Only 37 people participated. That's not a large enough sample to guarantee that the memory increase over three months of consuming the flavanol-enriched cocoa was really the reason for improved memory.  Just a few anomalies in a data set that small can corrupt the findings.

Nevertheless, I am always charmed by research that finds benefits to chocolate consumption. I'm tempted to focus only on those studies and not the ones that offer cautions.  But if I want to be a reasonable person, I have to look at the good and the bad effects of chocolate consumption.

The relationship between chocolate and memory is just now coming into focus.  I perceive this emerging research as a cousin to studies on the relationship between caffeine consumption and memory.  The relationship between chocolate and heart health has been more established.  But that's a post for another day.

For now, I'm limiting myself to one square of dark chocolate a day--on days that I actually let science dictate my behavior.

Related:

Nutrition for Our Age
Cognitive Changes: The Usual Suspects