Polyphenol in cocoa and red wine reduces stroke risk through gut-brain axis, experts flag

06 Oct 2022 --- A new study has revealed that, when consumed in the right amounts, B-type procyanidins can decrease the risk of stroke and other cardiovascular diseases (CVDs) while supporting the central nervous system (CNS) and improving cognitive function. However, if not consumed in the optimal quantities, the effects can be weakened or even nullified.

The authors note that the peak benefits of the micronutrient can only be reached with mid-range doses, a phenomenon known as hormesis. This class of polyphenol is abundant in red wine, cacao, apples, grape seeds and other foods.

Usually, bioactive compounds follow monotonic patterns where an increase in dosage elicits a higher response. Compounds that follow hormesis elicit an inverted U-shaped pattern, where the effect increases as you approach optimal amounts and then declines as more of the compound is introduced.

“These results are consistent with those of intervention studies following a single intake of food rich in B-type procyanidin and support the U-shaped dose-response theory, or hormesis, of polyphenols,” explains Dr. Naomi Okabe, lead author of the study and professor at the Shibaura Institute of Technology in Saitama, Japan.

Finding the sweet spotB-type procyanidins are abundant in apples, cocoa and red wine.
Since the compound’s effects can become null or even toxic at high doses, and lower doses can create a tolerance to polyphenol’s effects, the researchers wanted to quantify the optimal dose and its effects using data from previous studies. 

The researchers note that though several in vitro (outside the body of the test subject) studies had been conducted, no results had been verified in vivo (taking place inside a living organism).

To test the effects of the B-type procyanidins, the research team conducted in vivo experiments to monitor the effects on CNS neurotransmitter receptor activation in rats. The rats were given doses of 710 mg cocoa flavanols by themselves and then with either an a1 or a2 adrenaline blocker. 

The study, published in Frontiers of Nutrition, found that the polyphenol increased alertness and raised blood pressure and heart rate. A tenfold dose did not increase this effect – rather, it lessened it. The a1 blocker also reduced the effect, while the a2 blocker had a temporary increasing effect.

“Since a2 blockers are associated with the down-regulation of the SNS, the reduced metabolic and thermogenic outputs at a high dose of B-type procyanidins seen in our study may have induced α2 auto-receptor activation,” states Okabe. “Thus, SNS deactivation may be induced by a high dose of B-type procyanidins.”

Reaping the benefits
Since the studied effects of B-type procyanidins are well established and revealed that they could successfully be used to control glucose intolerance, hypertension and dyslipidemia – a form of lipid imbalance in the blood – proving that a correct dose could use the gut-brain axis to influence and improve symptoms is deemed important by the researchers. 

Moreover, the study states that its results back up and lend credence to previous in vitro study findings. 

“Though the exact relation between B-type procyanidins and the CNS needs more research, the health benefits of B-type procyanidin-rich foods remain undisputed,” state the authors.

Edited by William Bradford Nichols