From a systematic review of 10 randomized clinical trials: chocolate has blood pressure lowering capacity. Dark chocolate has a high content of flavanols. Flavonoids are the part of chocolate important for health benefits. They can also be found in high concentrations in certain fruits and vegetables. In the context of human nutrition, certain teas, grape juice, wine, various berries, and especially cocoa represent noteworthy sources. Dark chocolate has the highest content of flavonoids compared to the other sources. Besides lowering the blood pressure chocolate containing flavonols also has other cardioprotective properties.
On average over all trials chocolate reduced blood pressure. Systolic blood pressure was reduced with 4.5 mmHg and diastolic blood pressure with 2.5 mmHg. Treatment duration of these 10 randomized clinical trials ranged from 2 to 18 weeks. Participants were either healthy without hypertension or patients with stage 1 hypertension. Definition of stage 1 hypertension:
A minimum blood pressure value of 140/90. Stage 1 Hypertension is an early form of high blood pressure, and may require treatment with medicine, together with frequent monitoring, in order to avoid progression to Stage 2 Hypertension.
Possible mechanism of action of the blood lowering effect of chocolate are:
- increase in vasodilating nitric oxide bioavailability possibly caused, in part, by an enhanced nitric oxide synthase activity
- the inhibition of angiotensin converting enzyme activity
The chocolate dosage varied widely across studies, so still no answer to the important question: How much chocolate a day keeps hypertension away?. Moreover, chocolate is high in calories, one of the side-effects could be weight gain which is another risk factor for hypertension and other cardiovascular diseases. Were looking for very flavanols rich dark chocolate in optimal dose.
Desch, S., Schmidt, J., Kobler, D., Sonnabend, M., Eitel, I., Sareban, M., Rahimi, K., Schuler, G., & Thiele, H. (2009). Effect of Cocoa Products on Blood Pressure: Systematic Review and Meta-Analysis American Journal of Hypertension, 23 (1), 97-103 DOI: 10.1038/ajh.2009.213