If I told you that cocoa products such as cocoa powder and dark chocolate can lower your blood pressure, improve your gut health, and speed your recovery from exercise, I’m guessing you might look at me as if I have two heads. However, this seems to be the case. Continuing from the previous blog in which we unpacked the effects of cocoa intake on brain health, today we’ll consider how cocoa affects other aspects of how we feel and function each day.
Consuming cocoa flavanols improves the function of blood vessels and lowers blood pressure, especially in people with high blood pressure. The optimal dose for these effects is about 710 mg cocoa flavanols.
People who eat more chocolate seem to have lower risks of strokes, heart attacks, and coronary heart disease.
Cocoa has small positive effects on a range of metabolic health outcomes, including bodyweight, blood sugar control, and blood lipids.
Cocoa is a “prebiotic”, increasing numbers of microorganisms in the gut that are generally considered “healthy” and reducing numbers of pathogenic microorganisms.
Cocoa protects against excessive exercise-induced oxidative stress and might be particularly helpful for physical function in people with poor cardiovascular health.
Cocoa and cardiovascular health
If you read the last blog, you’ll know that cocoa flavanols enhance brain bloodflow and support the formation of blood vessels in brain regions that are crucial to learning and memory. Based on this, you might expect cocoa to be good for overall cardiovascular health. Sure enough, this seems to be the case.
Scientists have scrutinised how cocoa intake affects many facets of cardiovascular health – everything from the function of individual blood vessels to risk of cardiovascular diseases. Beginning with blood vessels, a recent systematic analysis of 15 studies showed that cocoa consumption improves endothelial function (flow-mediated dilatation), increasing how much arteries dilate in response to surges in bloodflow. This analysis found that 710 mg total cocoa flavanols (or 95 mg epicatechin, a key flavanol) most strongly enhances endothelial function.
As endothelial function influences blood pressure - a wide blood vessel tube (lumen) offers less resistance than a narrow one - it’s no surprise that cocoa intake can reduce blood pressure. Looking at controlled studies, cocoa supplementation reduces both systolic blood pressure (how much pressure blood exerts against artery walls as your heart beats) and diastolic blood pressure (pressure against artery walls between heartbeats) by about 1.8 mmHg. For people who have high blood pressure, cocoa intake can lead to even larger drops in blood pressure. While it isn’t clear what the best dose for this effect is, the average used in studies is about 670 mg total cocoa flavanols, which is similar to the ideal dose for endothelial function.
Then there are the effects of cocoa intake on actual cardiovascular disease. This is harder to study, for these diseases generally take years to develop and occur relatively infrequently. Because of this, studies of human cardiovascular disease aren’t tightly controlled and instead tend to ask large cohorts of people about their habitual intakes of cocoa-rich items (often just chocolate) and then follow their health over several years. When results of such studies have been compiled, people who have higher weekly chocolate intakes have lower risks of strokes, heart attacks, and coronary heart disease, but not heart failure or atrial fibrillation. To be clear, these types of studies have stark limitations (for one, a bar of Galaxy chocolate isn’t the same as a bar of Montezuma’s dark chocolate), but the data are intriguing and consistent with the cardiovascular health-boosting effects of flavanols seen in rigorous, placebo-controlled experiments.
You might be wondering about precisely what positive effects cocoa products are having in these studies. Cocoa flavanol intake seems to lead to activation of an enzyme (nitric oxide synthase) in the cells that line blood vessels (endothelial cells), increasing production of a gas (nitric oxide) that changes how blood vessels handle calcium, causing relaxation and dilation of these vessels. Cocoa’s antioxidant and anti-inflammatory actions are also heart friendly, and some people believe cocoa intake inhibits platelet aggregation. The jury’s still out on this effect, but if it's real it would be advantageous, for platelet aggregation contributes to blood clots.
Cocoa and metabolic health
Cardiovascular health is intimately tied to general metabolic health – how fat you are, your blood sugar control, and so on – so you might expect that cocoa influences metabolic health too.
While the effects of cocoa or dark chocolate intake on bodyweight and body fat aren’t clear, it does seem that high(ish) amounts of cocoa and dark chocolate (at least 30 g per day) for 4 to 8 weeks modestly reduce bodyweight. We won’t get into the weeds of the metabolic pathways that might be at play here, but perhaps this effect relates to both increased fat breakdown (lipolysis) and reduced fat synthesis (lipogenesis) after intake of some substances in cocoa (e.g., flavanols and caffeine). It’s also likely that effects are product dependent: Eating a 500-calorie bar of chocolate is quite different to drinking 50 calories of cocoa, even though both might contain similar quantities of flavanols, caffeine, and fibre.
Effects of cocoa on fat metabolism are also evident when blood lipids are measured. Specifically, cocoa intake can lower triglycerides and raise high-density lipoprotein cholesterol, both of which are likely to keep your doctor happy. There is also quite convincing evidence that cocoa intake improves other key aspects of metabolic health, such as insulin sensitivity, a determinant of risk of diseases including diabetes. Importantly, cocoa and dark chocolate intake can also help blood sugar regulation in diabetes patients by reducing fasting blood sugar. Under the hood, some of these effects are probably due to slowed carbohydrate digestion and altered insulin signaling and glucose transport in organs key to metabolic control, such as the liver, skeletal muscle, and adipose tissue.
Effects of cocoa on gut health and inflammation
You’re probably familiar with the term “prebiotic”, for prebiotics have been all the rage for the last few years. Technically, a prebiotic is “a substrate that is selectively utilized by host microorganisms conferring a health benefit”. Going by this definition, cocoa is a prebiotic, and a study of healthy adults exemplified this nicely.
After 4 weeks of consuming a cocoa drink each day (containing 494 mg cocoa flavanols), analysis of participants’ stool samples revealed that cocoa consumption increased numbers of microorganisms that are generally considered “healthy” (bifidobacteria and lactobacilli) and reduced numbers of pathogenic microorganisms (clostridia). Interestingly, the change in lactobacilli associated with reductions in C-reactive protein, a protein made by the liver that is used as an approximation of systemic inflammation. So, these results suggest that cocoa flavanols reached the intestine, where their metabolism modified gut microorganism composition in a way that subsequently reduced systemic inflammation. This is good news when we recognise how burdensome chronic inflammation is.
Cocoa and exercise performance and recovery
Let’s now turn our attention to exercise. There have now been many studies of cocoa product intake and exercise performance and recovery from exercise. While this research hasn’t convincingly shown that cocoa affects exercise performance or recovery from exercise, it does appear that cocoa reduces exercise-induced oxidative stress, which in some instances might be helpful.
We do need more research on cocoa and exercise though, for some work has shown interesting effects on physical function. For example, a recent publication reported that daily flavanol-rich cocoa intake for 6 months meaningfully improved walking in patients with peripheral artery disease, probably because cocoa enhanced calf muscle blood flow and led to the formation of new capillaries and improved mitochondrial function in these muscles. Cool, right?
I’m also excited to see the results of work that Keith Barr is doing on cocoa intake and tendon health. While the research hasn’t been published yet, I’ve heard Keith say his research group has found that drinking flavanol-rich cocoa improves collagen synthesis in tendons, which might be both helpful for tendon injury prevention and performance in events in which stiff tendons aid performance (i.e., power sports, such as sprinting). Incidentally, as skin is rich in collagen, this effect of cocoa on collagen might be one reason that several studies have found that cocoa intake is good for skin health, although most researchers have focused on the notion it is the antioxidants in cocoa that defend skin against sun damage.
Pass me the chocolate, please ;-)
Truth be told, these two articles have barely scratched the surface of the science of cocoa. I hope you’ve found them interesting and helpful though!
I really dislike the word “superfood”. But when you combine the taste of cocoa, the diversity of cocoa products, and the effects of cocoa intake on health, it really is pretty super, isn’t it?