by Craig Weatherby
We reported on findings about poor blood flow promoting Alzheimer’s elsewhere in this issue (See "Blood Starved Brains").
Coincidentally, that news was accompanied by related reports concerning the brain-boosting of cocoa, tea, and red wine.
Each of these foods and beverages is especially rich in a class of potent antioxidants called flavanols.
Perhaps more important than their direct antioxidant effects, flavanols appear to enhance multiple aspects of circulatory health via their impacts on gene expression, nitric oxide production, and inflammation.
Study #1 -Cocoa boosts blood flow to the brain
Research by Harvard scientists, supported by chocolate giant Mars, suggests that raw, flavanol-rich cocoa and chocolate made from it may boost blood flow in the brain and thereby reduce the risk of dementia and stroke (Sorond FA et al. 2008).
Most cocoa is “Dutched” (treated with alkali) to reduce bitterness and create a darker, more uniform color, but this removes most of the flavanols, rendering a highly healthful food into plain starch and fat.
(Our organic extra-dark chocolate is made with raw, un-Dutched cocoa.)
The new findings fit with those of prior studies, which link flavanol-rich cocoa products to improved arterial performance and cardiovascular health.
But this is the first study to examine the effect of flavanol-rich cocoa (FRC) on cerebral blood flow.
The small pilot study examined the effects of regular intakes of flavanol-rich cocoa (FRC) or flavanol-poor cocoa (FPC) in 34 healthy elderly volunteers with an average age of 72.
Researchers divided the volunteers into two groups:
- 13 people were assigned to consume FRC for two weeks and the blood flow in their brains was analyzed.
- 21 participants were randomized to receive either daily FRC or FPC for one week in a double-masked, placebo-controlled, parallel-arm study.
Ultrasound machines were used to measure blood flow velocity in the participants' middle cerebral arteries (MCA), with results encouraging for lovers of dark chocolate and raw cocoas:
- Two weeks of consuming flavanol-rich cocoa (FRC, at 900 mg per day) was associated with a 10 percent increase in blood flow.
- One week of flavanol-rich cocoa (FRC) was associated with an increase in blood flow of at least 10 percent in 55 percent of the participants.
- Consumption of flavanol-poor cocoa (FPC) was associated with a blood flow increase in only one in 10 participants.
However, large variations in blood flow changes amongst the subjects, and their small number, mean that these differences, while stark and highly suggestive, were not statistically significant.
Cocoa flavanols improve blood flow by increasing production of nitric oxide (NO), a molecule used by the endothelium (artery lining) to signal surrounding muscle to relax.
The researchers also noted that FRC contains some caffeine and theobromine, which tend to constrict blood vessels and reduce blood flow.
Therefore, any increase in cerebral blood flow occurs despite the contrary effects of the caffeine and theobromine in cocoa: a testament to the blood-flow-enhancing power of flavanols.
As the authors concluded, “Our results reinforce and extend previously published pilot data in healthy young women, and suggest that FRC intake directly increases cerebral blood flow in healthy elderly subjects.”
Study #2 - Chocolate, wine and tea improve brain performance
According to Oxford University researchers working with colleagues in Norway, chocolate, wine and tea enhance cognitive performance (Nurk E et al. 2008).
The team from Oxford’s Department of Physiology, Anatomy and Genetics and Norway examined the relation between cognitive performance and the intake of chocolate, wine, and tea in 2,031 people aged between 70 and 74.
Participants filled in information about their habitual food intake and underwent a battery of cognitive tests.
Those who consumed chocolate, wine, or tea had significantly better mean test scores and lower prevalence of poor cognitive performance than those who did not. The effect was most pronounced for wine.
Tea, red wine, and cocoa are major sources of flavanols.
The latest findings seem to support epidemiological evidence suggesting that people who consume lots of flavonols have a lower risk of dementia.
- Fisher ND, Sorond FA, Hollenberg NK. Cocoa flavanols and brain perfusion. J Cardiovasc Pharmacol. 2006;47 Suppl 2:S210-4.
- Nurk E, Refsum H, Drevon CA, Tell GS, Nygaard HA, Engedal K, Smith AD. Intake of Flavonoid-Rich Wine, Tea, and Chocolate by Elderly Men and Women Is Associated with Better Cognitive Test Performance. J Nutr. 2009 Jan;139(1):120-127. Epub 2008 Dec 3.
- Sorond FA, Lipsitz LA, Hollenberg NK, Fisher ND. Cerebral blood flow response to flavanol-rich cocoa in healthy elderly humans. Neuropsychiatr Dis Treat. 2008 Apr;4(2):433-40.