December 31, 2014
Men and women who consumed a cocoa-rich diet for three months did much better on memory tests than those who did not, a small but rigorous new study reports. The findings provide new support that chocolate, thought to provide a variety of benefits for heart health, may be good for the brain as well.
The study was conducted in 37 healthy men and women aged 50 to 69. Some drank a specially prepared cocoa beverage high in flavanols, the antioxidants found in dark chocolate. Others supplemented their daily meals with a drink containing a scant amount of cocoa antioxidants.
After three months, those consuming the flavanol-rich diet scored much higher on memory tests than those on the low-flavanol diet. The tests measured the kind of memory skills required to remember where you parked your car, for example, or to recall the face of someone you just met. Remarkably, even though the study participants were in their 50s and 60s, many of those drinking the cocoa-rich beverage performed as well as those in their 30s and 40s.
Brain scans using a technique called functional MRI showed that the cocoa supplement improved blood flow to the hippocampus, a part of the brain critical for thinking and memory. Specifically, blood flow increased to an area of the hippocampus called the dentate gyrus, deterioration of which is thought to be involved in age-related memory loss and the onset of “senior moments.”
Earlier studies in mice have shown that the antioxidants bolster connections between neurons in the brain, and specifically in the hippocampus. The same thing may be happening in people, the researchers said.
The hippocampus is also affected by Alzheimer’s disease. But none of the participants in this study had Alzheimer’s or other forms of dementia. Alzheimer’s causes extensive damage to this part of the brain, and the researchers said it was unlikely that chocolate would have notable benefits for someone already affected by the disease.
You’d also have to eat a lot of chocolate to get the levels of antioxidants used in the study. Participants in the high-cocoa group consumed the equivalent of 900 milligrams of cocoa flavanols daily, the amount found in about 25 candy bars.
Flavanols are found mainly in dark chocolate. Milk chocolate is low in the antioxidants, and the methods used to process cocoa typically strip it of much of its flavanol content.
The scientists who conducted the study said they are not sure how long the benefits might last, and whether lower amounts of cocoa consumption might provide similar benefits.
One of the backers of the study was the candy maker Mars, which makes a cocoa supplement called CocoaVia that contains lower amounts of flavanols. But the study was also supported by the National Institutes of Health, and researchers said that it was rigorously designed and conducted.
Flavanols are also found in tea, apples and some vegetables, though in much lower amounts than those used in the study.
The results more firmly establishes that the dentate gyrus is the anatomical source of age-related memory loss, said Scott Small, the study’s senior author and director of the Alzheimer’s Disease Research Center at the Taub Institute at Columbia University Medical Center. He said the study also offered yet more evidence that diet and lifestyle measures that increase blood flow to the brain can slow or reverse age-related cognitive decline.
Source: Adam M Brickman, Usman A Khan, Frank A Provenzano, et al: “Enhancing Dentate Gyrus Function With Dietary Flavanols Improves Cognition in Older Adults.” Nature Neuroscience, Oct. 26, 2014