Cocoa: How Flavanols Affect Blood Pressure and Metabolism
Laura Chrobok 26.10.2026
Rich in flavour, aromatic, bittersweet. Almost irresistible to many. But cocoa can do far more than provide pleasure. Cocoa beans contain plant compounds that help our blood vessels remain flexible and regulate blood flow. And that’s not all: flavanols can also have beneficial effects on blood pressure, certain cholesterol levels and even insulin sensitivity.
Chocolate is healthy? Let’s take a closer look.
Cocoa Flavanols: The Special Plant Compounds Found in Cocoa Beans
The cocoa tree (Theobroma cacao) originally comes from tropical America. Its fruits contain cocoa beans, which are used to produce cocoa mass, cocoa butter and cocoa powder, among other things.
Alongside fat, protein and various minerals, the beans contain numerous secondary plant compounds. Of particular scientific interest are polyphenols, which include flavonoids. Flavanols, more precisely flavan-3-ols, form a subgroup of these flavonoids.
The most important representatives of these compounds in cocoa include:
o Epicatechin: A bioactive plant compound whose influence on vascular function and the availability of nitric oxide is being investigated.
o Catechin: A chemically related compound with antioxidant properties.
o Procyanidins: Plant compounds consisting of several linked flavanol units.
Epicatechin, in particular, plays a role in the beneficial vascular responses observed after consuming flavanol-rich cocoa (Schroeter et al., 2006).
How Does Cocoa Affect Blood Vessels?
Our blood vessels are flexible. They can contract and relax to adjust blood circulation to the body’s needs at any given moment. A crucial role in this process is played by the endothelium, a thin layer of cells lining the inside of blood vessels which, among other things, helps regulate their diameter.
To do this, the endothelium produces various signalling molecules. One particularly important substance is nitric oxide, or NO. Nitric oxide causes the smooth muscle cells in blood vessel walls to relax. This allows the vessels to widen, supporting blood flow.
Cocoa flavanols can influence precisely this mechanism.
In 2006, scientists investigated how flavanol-rich cocoa affected vascular function in 10 healthy men. On different days, participants received either a cocoa drink containing 917 mg of flavanols or a control drink containing just 37 mg. Both preparations consisted of cocoa powder mixed with 300 ml of water.
Significantly improved blood vessel dilation was observed just one to four hours after consumption of the flavanol-rich drink. At the same time, blood concentrations of certain nitric oxide-related compounds increased during the first three hours. Blood flow through small blood vessels also improved (Schroeter et al., 2006).
The researchers thus provided a specific biochemical explanation for how cocoa flavanols can have beneficial effects on the function of our blood vessels.
How Does Cocoa Affect Blood Pressure?
Numerous clinical studies show that these properties can also be reflected in measurable changes in blood pressure.
A Cochrane review published in 2017 included 35 randomised studies involving a total of 1,804 predominantly healthy adults. The studies lasted between two and 18 weeks. Data from 1,772 participants were available for calculating diastolic blood pressure.
Compared with the respective control groups, there was a small but statistically significant reduction in blood pressure. Systolic blood pressure was an average of 1.76 mmHg lower, as was diastolic blood pressure.
The scientists interpreted these findings as evidence of a short-term blood-pressure-lowering effect of flavanol-rich cocoa preparations (Riedl et al., 2017).
A New Meta-Analysis Confirms Beneficial Effects
A systematic review and meta-analysis published in September 2026 adds recent clinical data to these findings (Sakuda et al., 2026).
The researchers evaluated 25 randomised controlled trials involving a total of 1,167 participants. Daily cocoa flavanol doses ranged from 10.6 to 1,680 mg. The studies included people with both normal and elevated blood pressure.
Compared with the control groups, the pooled results showed an average:
o 2.73 mmHg reduction in systolic blood pressure
o 1.85 mmHg reduction in diastolic blood pressure
o 1.31 percentage point improvement in flow-mediated dilation
o 0.20 m/s reduction in pulse wave velocity
Flow-mediated dilation (FMD) is measured using ultrasound. It indicates how well an artery can widen in response to increased blood flow. Pulse wave velocity, meanwhile, provides information about arterial stiffness. A lower value may indicate better vascular elasticity.
The scientists also found indications of a relationship between the amount of flavanols consumed and the extent of the changes in blood pressure.
However, it was not possible to establish a clearly effective minimum dose. When evaluating the findings, it should also be noted that several authors are employed by food manufacturers or consultancy companies.
Nevertheless, the recent meta-analysis confirms the beneficial effects on blood pressure and certain measures of vascular function observed in earlier studies.
How Do Cocoa Flavanols Affect Cholesterol?
Cholesterol levels may also benefit from cocoa flavanols. This was demonstrated in a clinical study involving 100 healthy women and men aged between 35 and 60.
Participants received either 900 mg of cocoa flavanols or a flavanol-free control drink daily for four weeks.
At the end of this period, total cholesterol in the flavanol group was an average of 0.20 mmol/l lower than in the control group. LDL cholesterol, commonly referred to as “bad” cholesterol, also fell by 0.17 mmol/l, while “good” HDL cholesterol increased by 0.10 mmol/l.
All three changes were statistically significant (Sansone et al., 2015).
Cocoa flavanols can therefore have beneficial effects on various measures of vascular function and lipid metabolism simultaneously within just a few weeks.
How Do Cocoa Flavanols Affect Glucose Metabolism?
Cocoa flavanols may also play an interesting role in glucose metabolism. For glucose to move from the blood into our body’s cells, we need the hormone insulin. If the cells no longer respond adequately to insulin, this is known as insulin resistance — an important risk factor for type 2 diabetes.
A clinical study involving 19 adults with high blood pressure and impaired glucose tolerance demonstrated how flavanol-rich cocoa can influence this process. Participants received either 100 g of flavanol-rich dark chocolate or a comparable amount of flavanol-free white chocolate daily for 15 days each.
The result: insulin resistance was significantly lower after consumption of the flavanol-rich chocolate. The body’s cells became more sensitive to insulin, and the function of the insulin-producing cells in the pancreas also improved (Grassi et al., 2008).
These findings are promising. However, the chocolate used was specially selected for the study — not ordinary chocolate from the supermarket.
There is therefore clinical evidence that cocoa flavanols can also influence insulin regulation. Whether this can reduce the long-term risk of type 2 diabetes remains to be clarified in appropriate long-term studies. This is not a recommendation to eat 100 g of chocolate daily.
The Effects of Cocoa Flavanols Are Recognised by the EFSA
One distinctive feature of cocoa flavanols is that their effects on normal vascular function have already been scientifically assessed by the European Food Safety Authority (EFSA).
In 2012, the EFSA concluded that there was a cause-and-effect relationship between cocoa flavanol consumption and the maintenance of normal endothelium-dependent vasodilation.
On this basis, the following health claim was authorised in the European Union:
“Cocoa flavanols help maintain the elasticity of blood vessels, which contributes to normal blood flow.”
According to EU regulations, a daily intake of 200 mg of cocoa flavanols is required for this effect. Relevant products must enable a daily intake of at least 200 mg of cocoa flavanols with a degree of polymerisation of 1 to 10. Consumers must also be informed of the required daily intake under EU regulations.
The fact that a specific positive physiological effect of cocoa flavanols on our blood vessels has been scientifically recognised highlights their special position within nutritional medicine research (EFSA NDA Panel, 2012; Europäische Kommission, 2015).
Not All Cocoa Is the Same: Why Processing Matters
Anyone wishing to consume cocoa flavanols specifically should be aware that their concentration can change considerably during processing.
The cocoa percentage stated on chocolate packaging is not a reliable indicator of the actual flavanol content either. Dark chocolate is not necessarily particularly rich in flavanols. For those seeking to consume specific amounts, a clearly stated and verifiable flavanol content is therefore more important than the dark colour or cocoa percentage alone (Langer et al., 2011).
Tolerability of Cocoa Flavanols
Cocoa flavanols have generally been well tolerated in clinical studies, even at higher doses.
Possible adverse effects include:
· nausea and other gastrointestinal complaints
· headaches
· individual intolerance reactions
It should also be noted that, depending on their composition, cocoa products may contain caffeine and theobromine, to which sensitive individuals may react (Ottaviani et al., 2015).
Anyone regularly taking blood-pressure-lowering medicines should seek medical or pharmaceutical advice before additionally using concentrated extracts because of their potential effects on blood pressure.
Cocoa and Health: Flavanols Make (Little) Indulgences Worthwhile
The health significance of cocoa extends far beyond its value as a pleasurable treat. In particular, the flavanols it contains can influence processes that are important for our blood vessels and metabolism.
What matters, however, is how much of these plant compounds a particular cocoa product actually contains. Considerable quantities can be lost during processing. Anyone specifically looking for cocoa flavanols should therefore not rely solely on the cocoa percentage, but preferably choose products with a clearly stated and verifiable flavanol content.
It is precisely the combination of well-researched vascular effects and other beneficial metabolic findings that makes cocoa flavanols remarkable plant compounds whose health potential is increasingly being explored scientifically.
FAQ — More Frequently Asked Questions About Cocoa and Flavanols
1. Are flavanols and flavonols the same?
No. Although the names sound similar, they are two different subgroups of flavonoids.
Flavanols, also known as flavan-3-ols, include catechin and epicatechin, for example. Flavonols, by contrast, form a separate group of compounds, whose best-known representatives include quercetin and kaempferol. Both groups are secondary plant compounds, but they differ in their chemical structures and biological properties.
2. Are flavanols also found in other foods?
Yes. In addition to cocoa, green and black tea, apples, grapes and various berries contain flavanols.
However, the types and concentrations of flavanol compounds found in these foods can vary considerably.
3. Can dairy products interfere with flavanol absorption?
Milk proteins can interact with plant polyphenols. Whether this also affects the absorption of cocoa flavanols has been investigated in clinical studies, but the findings have been inconsistent. It is therefore not possible to make a general claim to this effect.
4. Can flavanols interfere with sleep?
There is currently no convincing clinical evidence that flavanols themselves directly interfere with sleep.
However, alongside flavanols, cocoa also contains caffeine and theobromine. These so-called methylxanthines have stimulating properties, although theobromine stimulates the central nervous system less strongly than caffeine. In sensitive individuals, consuming larger quantities of cocoa-containing products in the evening may therefore interfere with sleep. The decisive factors are the amounts of caffeine and theobromine present and individual sensitivity — not the flavanol content alone.
Further information on cocoa flavanols — and, of course, many other topics — can be found on our blog, in our “Medizinskandale” book series and in the “Codex Humanus,” the fifth volume of which was recently published. We look forward to welcoming you to our online shop.
Sources:
· Schroeter, H. et al. (2006): “(-)-Epicatechin mediates beneficial effects of flavanol-rich cocoa on vascular function in humans,” Proceedings of the National Academy of Sciences.
· Ried, K. et al. (2017): “Effect of cocoa on blood pressure,” Cochrane Database of Systematic Reviews.
· Sakuda, M. et al. (2026): “Impact of cocoa flavanols on blood pressure and vascular function: an updated systematic review and meta-analysis of randomized controlled trials,” The Journal of Nutrition, Health & Aging.
· Sansone, R. et al. (2015): “Cocoa flavanol intake improves endothelial function and Framingham Risk Score in healthy men and women: a randomised, controlled, double-masked trial: the Flaviola Health Study,” British Journal of Nutrition.
· Grassi, D. et al. (2008): “Blood pressure is reduced and insulin sensitivity increased in glucose-intolerant, hypertensive subjects after 15 days of consuming high-polyphenol dark chocolate,” The Journal of Nutrition.
· EFSA NDA Panel (2012): “Scientific Opinion on the substantiation of a health claim related to cocoa flavanols and maintenance of normal endothelium-dependent vasodilation pursuant to Article 13(5) of Regulation (EC) No 1924/2006,” EFSA Journal.
· Europäische Kommission (2015): “Verordnung (EU) 2015/539 der Kommission vom 31. März 2015 zur Zulassung einer anderen gesundheitsbezogenen Angabe über Lebensmittel als Angaben über die Reduzierung eines Krankheitsrisikos sowie die Entwicklung und die Gesundheit von Kindern und zur Änderung der Verordnung (EU) Nr. 432/2012,” Amtsblatt der Europäischen Union.
· Langer, S. et al. (2011): “Flavanols and methylxanthines in commercially available dark chocolate: a study of the correlation with nonfat cocoa solids,” Journal of Agricultural and Food Chemistry.
· Ottaviani, J. I. et al. (2015): “Safety and efficacy of cocoa flavanol intake in healthy adults: a randomized, controlled, double-masked trial,” The American Journal of Clinical Nutrition.
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