Last year, a Columbia University researcher whimsically reported that the number of Nobel Prize winners in a particular country is “powerfully correlated” with the amount of chocolate that country consumes.
That hardly proved cause and effect, noted other researchers, since a country’s chocolate consumption is correlated with a long list of unrelated things—the number of IKEA stores, for instance.
Still, there could be something to the link between chocolate and the brain, at least for some people.
“We know that flavanols and the compounds they’re metabolized into can cross into the brain and improve blood flow there,” says Harvard flavanol researcher Naomi Deirdre Fisher.
“And we’re learning from animal studies that flavanols may also promote neurogenesis, which is the development of nerves, as well as improve nerve function and the connections between nerves.”
Mars is hot on the trail. “We now have emerging evidence that cocoa flavanols may improve cognitive function in some people, though this is still a very early area of research,” says Mars Symbioscience researcher Catherine Kwik-Uribe.
In a study funded by Mars, she and her colleagues gave 90 Italian men and women with mild cognitive impairment a daily cocoa drink with one of three levels of flavanols: 990 milligrams, 520 milligrams, or 45 milligrams (which served as the control).
(Mild cognitive impairment is memory decline beyond what normally occurs with age. While MCI is not severe enough to interfere with daily life, people with the condition are about three to five times more likely to develop dementia than people without MCI, according to the Alzheimer’s Association.)
After two months, those who were consuming 990 mg scored higher on a test of verbal fluency than those getting 45 mg. Asked to name as many nouns as they could that began with a certain letter within 60 seconds, the high-flavanol group averaged 28, while the low-flavanol group averaged 22. The 520 mg group did no better than the 45 mg (placebo) group.
But both higher groups did better on a test of attention, organization, and memory. Asked to draw a line between a series of consecutive numbers, those getting 990 mg or 520 mg of flavanols a day completed the task in an average of 39 seconds, while those getting 45 mg took 53 seconds.
But when 71 healthy Australian men and women aged 40 to 65 consumed a beverage with 250 mg or 500 mg of cocoa flavanols or a placebo every day for a month, researchers couldn’t detect any improvements in attention, memory, and other cognitive tasks in those getting flavanols.
Interestingly, when the participants filled out questionnaires at the end of the study, the 24 who had consumed 500 mg of flavanols every day reported feeling calmer and more content than those who had consumed 250 mg of flavanols or the placebo beverage.
Clearly, more studies on flavanols and cognition are needed.
“There are reasons to be hopeful, to suspect that there’s benefit, based on test tube studies, animal studies, human population studies, and a few clinical trials,” says Fisher.
But solid evidence is lacking, she adds. “We haven’t administered flavanols for five years to a set of healthy people over 65 and seen that there was less cognitive decline in those who had higher consumption. Those studies haven’t been done.”
Sources: N. Engl. J. Med. 367: 1562, 2012; J. Nutr. 143: 931, 2013; Hypertension 60: 794, 2012; J. Psychopharmacol. 27: 451, 2013.