Cacao and Flavanols: The Science Behind the Bean

From Food of the Gods to Modern Research

In 1753, Swedish naturalist Carl Linnaeus gave the cacao tree its scientific name: Theobroma cacao. Translated, it means “food of the gods.” The Maya and Aztecs used cacao as a ceremonial drink and even as currency. What they knew intuitively, modern research is increasingly confirming: cacao contains a remarkable variety of bioactive compounds.

At the centre of scientific interest today are flavanols. These are secondary plant metabolites belonging to the polyphenol class. Cacao is among the richest natural sources of these compounds. An unprocessed cacao powder can contain over 3,000 mg of flavanols per 100 g. That is more than green tea, red wine, or most berry varieties.

What Are Flavanols?

Flavanols are a subgroup of flavonoids. They occur in many plants, but only a few foods deliver them in meaningful quantities. In cacao, one compound dominates: epicatechin. It is considered the key flavanol in cacao.

Epicatechin as the Key Molecule

Epicatechin is a monomeric flavanol with high bioavailability. This means the body can absorb it comparatively well. In studies, epicatechin from cacao reaches its peak plasma concentration within 1 to 2 hours (Schroeter et al., 2006).

Other flavanols in cacao:

Compound	Type	Characteristic
Epicatechin	Monomer	High bioavailability
Catechin	Monomer	Structurally related
Procyanidin B2	Dimer	Two linked units
Procyanidin C1	Trimer	Three linked units
Oligomeric procyanidins	Polymer	Larger chains, lower absorption

The larger the flavanol molecule, the less efficiently the body can absorb it. This is why epicatechin, as a monomeric flavanol, is considered especially relevant to human physiology.

The COSMOS Study: 21,000 Participants, 3.6 Years

The Cocoa Supplement and Multivitamin Outcomes Study (COSMOS) was one of the largest randomised controlled trials on dietary flavanols. Over 21,000 women aged 65 and older and men aged 60 and older took either 500 mg of cacao flavanols or a placebo daily. The study ran from 2015 to 2020 and was conducted at Brigham and Women’s Hospital in Boston.

Cardiovascular Outcomes

The primary analysis (Sesso et al., 2022) showed no significant reduction in major cardiovascular events across the overall population. However, a subanalysis found that participants with low fruit and vegetable intake benefited more. The data suggest that cacao flavanols can positively influence certain biomarkers of vascular health.

Cognitive Function

A COSMOS substudy (Baker et al., 2023) examined the effects on cognitive performance. Participants with low baseline flavanol intake showed improvements in memory tests after supplementation. The results support the hypothesis that flavanols may promote neuronal blood flow. Among participants who already had high dietary flavanol intake, the effects were smaller.

Theobromine: A Gentler Stimulant

In addition to flavanols, cacao contains theobromine. It is an alkaloid structurally related to caffeine. Theobromine acts more mildly and lasts longer than caffeine. Its half-life is 6 to 10 hours, compared to 3 to 5 hours for caffeine.

Stimulant comparison:

Property	Caffeine	Theobromine
Onset	Fast (15-30 min)	Slower (30-60 min)
Half-life	3-5 hours	6-10 hours
Stimulation	Strong, CNS-focused	Mild, peripheral
Blood pressure effect	Briefly elevating	Neutral to lowering

Studies suggest that theobromine can improve mood without the typical nervousness associated with caffeine (Martinez-Pinilla et al., 2015). A cup of raw cacao contains approximately 100 to 200 mg of theobromine but only 5 to 20 mg of caffeine.

Raw Cacao vs. Processed Chocolate

Not all cacao is created equal. Processing has an enormous impact on flavanol content. Studies show that up to 90% of the original flavanols can be lost through industrial processing (Miller et al., 2006).

Where Are Flavanols Lost?

• Fermentation. Necessary for flavour development. Flavanol losses of 10 to 20% depending on duration and temperature.
• Roasting. High temperatures degrade flavanols. Gentle roasting at lower temperatures preserves more flavanols.
• Alkalisation (Dutch Processing). Treatment with potassium carbonate to deepen colour and mellow flavour. This destroys 60 to 90% of flavanols.
• Added sugar and milk powder. These dilute the flavanol proportion and may reduce epicatechin absorption.

A typical milk chocolate product contains less than 50 mg of flavanols per 100 g. A gently processed raw cacao powder can contain over 3,000 mg per 100 g. The difference is substantial.

Minimum Effective Dose

The question of how many cacao flavanols are beneficial is actively being studied. A systematic review by Hooper et al. (2012, Cochrane Collaboration) analysed 42 randomised controlled trials.

Findings on dosage:

• From 200 mg of flavanols per day, several studies showed effects on vascular function.
• The COSMOS study used 500 mg per day.
• The EFSA (European Food Safety Authority) confirmed a health claim for cacao flavanols in 2012: 200 mg of flavanols per day can contribute to normal endothelial function.
• Mastroiacovo et al. (2015) showed that 520 mg and 990 mg of cacao flavanols per day improved cognitive performance in older adults, while 48 mg had no effect.

The range of 200 to 600 mg of flavanols per day is the most commonly cited relevant window in the literature. This corresponds to approximately 5 to 15 g of a high-quality raw cacao powder.

Quality Criteria: What to Look for in Cacao

Not every cacao product delivers relevant amounts of flavanols. The following criteria help with assessment:

• No alkalisation. Dutch Processing destroys most flavanols. Natural cacao is the better choice.
• Gentle processing. Low roasting temperatures preserve more bioactive compounds.
• Origin and variety. Criollo and Trinitario varieties are considered more aromatic and often richer in flavanols than Forastero. However, variation between individual batches is considerable.
• No additives. Pure cacao powder without sugar, milk powder, or artificial flavourings maximises the flavanol content per serving.
• Declared flavanol content. Some producers state the flavanol content on the packaging. This is the most reliable criterion.

Conclusion

Cacao is more than an indulgence. Scientific evidence shows that the flavanols in cacao, particularly epicatechin, are biologically active compounds. Large studies like COSMOS are delivering increasingly nuanced data. The results suggest that regular intake of 200 to 600 mg of cacao flavanols can support vascular function and cognitive performance.

Quality is decisive. Heavily processed cacao products and chocolate deliver very few flavanols. Raw cacao in gently processed form is the richest source. Those who wish to use cacao as a functional food should pay attention to processing, purity, and dosage.

---

Sources:

• Sesso HD et al. (2022). Effect of cocoa flavanol supplementation for prevention of cardiovascular disease events: the COSMOS randomized clinical trial. American Journal of Clinical Nutrition, 115(6), 1490-1500.
• Baker LD et al. (2023). Effects of cocoa extract and multivitamin on cognitive function: A randomized clinical trial. American Journal of Clinical Nutrition, 117(6), 1199-1207.
• Mastroiacovo D et al. (2015). Cocoa flavanol consumption improves cognitive function, blood pressure control, and metabolic profile in elderly subjects. American Journal of Clinical Nutrition, 101(3), 538-548.
• Hooper L et al. (2012). Effects of chocolate, cocoa, and flavan-3-ols on cardiovascular health: a systematic review and meta-analysis of randomized trials. American Journal of Clinical Nutrition, 95(3), 740-751.
• 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, 103(4), 1024-1029.
• Miller KB et al. (2006). Impact of alkalization on the antioxidant and flavanol content of commercial cocoa powders. Journal of Agricultural and Food Chemistry, 54(21), 8302-8306.
• Martinez-Pinilla E et al. (2015). The relevance of theobromine for the beneficial effects of cocoa consumption. Frontiers in Pharmacology, 6, 30.