IT IS THE HOLIDAY SEASON. You should not be surprised that I am here to talk about the nectar of the gods, dark chocolate.
“life is either
a daring adventure
or quiet moments spent with chocolate
and your tortured sanity.”
― Ben Ditmars
We begin with this observation: You may improve your blood flow and pressure by consuming dark chocolate. Here’s how the magic may happen — Flavanols in dark chocolate can stimulate the inner lining of our arteries, in turn leading these blood vessels to make nitric oxide.
Nitric oxide can then signal the arteries to relax. The result? Resistance to blood flow drops, resulting in blood pressure reduction. But do we have real-world data to support this observation? Indeed, we have some evidence of a mild effect on blood pressure.
In support of our observations, researchers at Harvard Medical School and Brigham and Women’s Hospital showed that flavanol-rich cocoa causes blood vessel widening via activation of the nitric oxide system. This finding supports the idea that nitric oxide is the agent through which dark chocolate protects against adverse heart events.
To see if cocoa consumption leads to blood pressure lowering, scientists in Cologne (Germany) searched for studies that assessed blood pressure before and after consuming cocoa products or black or green tea for at least one week.
The researchers identified five randomized clinical studies of cocoa. After the cocoa, the average systolic (top number) and diastolic (bottom number) blood pressure dropped by about 5 mm Hg and 8 mm Hg, respectively. On the other hand, black or green tea did not affect blood pressure. The study authors concluded this:
“Consumption of foods rich in cocoa may drop blood pressure, but tea has no such effect.”
Other studies demonstrate a mild positive effect of cocoa consumption on blood pressure. The improvement is typically slight.
Dark chocolate and heart health
Back to the real world. Is there any evidence that any of this translates into improvements in health? A small study from the Netherlands offers hope that we lovers of dark chocolate can improve our cardiovascular health.
We know that small and relatively short-term clinical studies show that cocoa can improve blood vessel function and reduce blood pressure. Dutch researchers examined 470 older men free of chronic diseases at baseline to better understand whether longer-term cocoa is related to blood pressure and cardiovascular death.
Scientists examined blood pressure (of participants in the Zutphen Elderly Study) at baseline and five years later. The researchers also determined causes of death during 15 years of follow-up, assessed food intake, and estimated cocoa intake.
One-third of the subjects consumed no cocoa at study entry. For the food consumers, the average intake was 2.11 grams daily. Let’s get to the findings:
- The average systolic (top number) blood pressure in the highest one-third of cocoa intake appeared about 4 mm Hg lower, and the average diastolic (bottom number) blood pressure by just over 2 mm Hg.
- Compared with the lowest one-third of cocoa intake, the men in the highest third appeared one-half less likely to die of cardiovascular disease, and all-cause death also appeared about 50 percent lower over 15 years.
“Well, he should have some chocolate, at the very least,’ said Madam Pomfrey”
― J.K. Rowling, Harry Potter and the Prisoner of Azkaban
A separate study revealed chocolate consumption to be inversely associated with heart artery plaque. Here are the odds ratios by the amount of chocolate consumed:
- No chocolate 1.0
- Chocolate one to three times per month 0.94
- Chocolate once per week 0.78
- Chocolate at least twice weekly 0.68
Put more simply, eating chocolate at least twice per week appeared associated with a one-third lower risk of developing coronary artery plaque.
Moreover, you may lower your LDL “bad” cholesterol with your dark chocolate consumption. Look at the results of this 2017 experiment with participants consuming almonds, with or without dark chocolate.
Here are the findings from the randomized feeding trial: Consumption of almonds alone, with or without dark chocolate, improves cholesterol (lipid) profiles. The study authors concluded this: “Incorporating almonds, dark chocolate, and cocoa into a typical American diet without exceeding energy needs may reduce the risk of coronary heart disease.”
Now I need to challenge my enthusiasm for dark chocolate. The studies I offer you are either relatively small or observational. The latter type of study does not allow us to establish a causal relationship between chocolate consumption and improved cardiovascular health. And the change in blood pressure is small. So take all of this with a grain of salt (I prefer sea salt!).
Please don’t head out and consume vast quantities of chocolate. Too many calories! I prefer to have a couple of squares after dinner. By limiting myself, the experience becomes even more special. Aim for dark chocolate that has at least 70 percent cocoa content.
Thank you for joining me today.