Theobromine

Research & Evidence

Theobromine is the main active constituent of cacao and is closely related to caffeine — the two differ by a single methyl group. It shares caffeine’s broad profile but with a characteristically different emphasis: it is a weaker stimulant of the central nervous system but has a more pronounced action on the heart, kidneys, bronchial muscle and peripheral blood vessels ^{1Reference 1A Modern Herbal | CacaoA Modern Herbal | Cacao. (n.d.). Retrieved from https://www.botanical.com/botanical/mgmh/c/cacao-02.htmlView study →}. Across the source-herb monographs the best-characterised activities are:

• Cardiac and bronchial action — theobromine is a purine-class alkaloid shown to stimulate the heart muscle, relax bronchial smooth muscle, and participate in the transmission of intracellular signals ^{1Reference 1A Modern Herbal | CacaoA Modern Herbal | Cacao. (n.d.). Retrieved from https://www.botanical.com/botanical/mgmh/c/cacao-02.htmlView study →}. This bronchodilating and vasodilating emphasis is what makes cacao of interest for airflow, altitude and athletic contexts, and it contributes to the gentler, “rounded” stimulation of yerba maté compared with coffee.
• Cardiovascular and lipid effects — theobromine has been studied for its ability to raise serum HDL (“good”) cholesterol, and it is identified as one of the primary bioactive compounds responsible for cocoa’s benefits, including its antihypertensive activity ^{2Reference 2Giovanni Scapagnini et al. · 2014Cocoa Bioactive Compounds: Significance and Potential for the Maintenance of Skin Health}. Because it stimulates the heart muscle, the source page on cacao notes its effect should be considered in patients on beta-blocking medication ^{1Reference 1A Modern Herbal | CacaoA Modern Herbal | Cacao. (n.d.). Retrieved from https://www.botanical.com/botanical/mgmh/c/cacao-02.htmlView study →}.
• Skeletal-muscle and metabolic effects — alongside paraxanthine and theophylline, theobromine produces dose-dependent increases in intracellular Ca2+ in skeletal muscle, an effect reduced by a calcium-channel blocker; this links the methylxanthines as a group to effects on muscle ^{4Reference 4T.J et al. · 2000Paraxanthine, a caffeine metabolite, dose dependently increases [Ca2+]i in skeletal muscle}.
• Immunomodulation (as part of cacao) — cacao’s methylxanthine and polyphenol content has been associated with immunomodulatory and anti-inflammatory activity, including effects mediated through tryptophan metabolism ^{3Reference 3Kathrin Becker et al. · 2013Immunomodulatory properties of cacao extracts — potential consequences for medical applications}.

Theobromine occurs at roughly 2% in cacao seeds and about 1% in the shells ^{1Reference 1A Modern Herbal | CacaoA Modern Herbal | Cacao. (n.d.). Retrieved from https://www.botanical.com/botanical/mgmh/c/cacao-02.htmlView study →}. It is also present in guarana, where it appears alongside caffeine and theophylline in the bark, leaves and flowers ^{5Reference 5Schimpl et al. · 2013Guarana: revisiting a highly caffeinated plant from the Amazon}, and in coffee as a minor xanthine alkaloid ^{6Reference 6Barceloux · 2012Medical Toxicology of Drugs Abuse: Synthesized Chemicals and Psychoactive Plants}. The references below are the studies cited on the source-herb pages that genuinely pertain to theobromine; this section will grow as more compound-specific research is added.

Toxicity & Safety

In humans, theobromine is well tolerated at dietary doses — which is why it is flagged here as low-toxicity — and it tends to produce milder stimulant side effects than caffeine. The most important caution is one of species toxicity rather than human risk: theobromine is the compound that makes chocolate and cacao dangerous to dogs (and other animals such as cats), which metabolise it far more slowly than people do, so cacao products should be kept well away from pets. In people, because theobromine stimulates the heart muscle, its effect is worth considering in anyone taking beta-blockers or other cardiac medication ^{1Reference 1A Modern Herbal | CacaoA Modern Herbal | Cacao. (n.d.). Retrieved from https://www.botanical.com/botanical/mgmh/c/cacao-02.htmlView study →}, and those sensitive to xanthine alkaloids should use cacao and the other theobromine-containing herbs cautiously.

References

1. A Modern Herbal | Cacao. (n.d.). Retrieved from https://www.botanical.com/botanical/mgmh/c/cacao-02.html
2. Giovanni Scapagnini, Sergio Davinelli, Laura Di Renzo, Antonino De Lorenzo, Hector Hugo Olarte, Giuseppe Micali, Arrigo F. Cicero and Salvador Gonzalez. (2014). Cocoa Bioactive Compounds: Significance and Potential for the Maintenance of Skin Health. Nutrients, 6, 3202–3213.
3. Kathrin Becker, Simon Geisler, Florian Ueberall, Dietmar Fuchs and Johanna M. Gostner. (2013). Immunomodulatory properties of cacao extracts — potential consequences for medical applications. Frontiers in Pharmacology, Vol 4, Article 154.
4. T.J. Hawke, D.G. Allen, M.I. Lindinger. (2000). Paraxanthine, a caffeine metabolite, dose dependently increases [Ca2+]i in skeletal muscle. Journal of Applied Physiology, Vol 89, 2312–2317.
5. Schimpl, F. C., da Silva, J. F., de Carvalho Gonçalves, J. F., & Mazzafera, P. (2013). Guarana: revisiting a highly caffeinated plant from the Amazon. Journal of Ethnopharmacology, 150(1), 14–31.
6. Barceloux, D. G. (2012). Medical Toxicology of Drugs Abuse: Synthesized Chemicals and Psychoactive Plants. Somerset, NJ, USA: John Wiley & Sons.