Theobromine, formerly known as xantheose, is a bitter alkaloid of the cacao plant, with the chemical formula C7H8N4O2

 It is found in chocolate, as well as in a number of other foods, including the leaves of the tea plant, and the kola (or cola) nut. It is classified as a xanthine alkaloid,  which also include the similar compounds theophylline and caffeine.  

The compounds differ in that caffeine has an extra methyl group.

Origin of the name

Despite its name, the compound contains no bromine—theobromine is derived from Theobroma, the name of the genus of the cacao tree, (which itself is made up of the Greek roots theo ("god") and broma ("food"), meaning "food of the gods”  with the suffix -ine given to alkaloids and other basic nitrogen-containing compounds. 


Cacao (Theobroma cacao) image: Luisovalles/wikipedia

Theobromine is a slightly water-soluble (330 mg/L), crystalline, bitter powder. Theobromine is white or colourless, but commercial samples can be yellowish .

It has an effect similar to, but lesser than, that of caffeine in the human nervous system, making it a lesser homologue. Theobromine is an isomer of theophylline, as well as paraxanthine. Theobromine is categorized as a dimethyl xanthine. 

When was it discovered or isolated?

Theobromine was first discovered in 1841  in cacao beans by Russian chemist Alexander Voskresensky.  Synthesis of theobromine from xanthine was first reported in 1882 by Hermann Emil Fischer.

What does it do to a person?

The amount of theobromine found in chocolate is small enough that chocolate can, in general, be safely consumed by humans. Theobromine poisoning may result from the chronic or acute consumption of large quantities, especially in the elderly.

Theobromine and caffeine are similar in that they are related alkaloids. Theobromine is weaker in both its inhibition of cyclic nucleotide phosphodiesterases and its antagonism of adenosine receptors.  Therefore, theobromine has a lesser impact on the human central nervous system than caffeine. 

Theobromine stimulates the heart to a greater degree. While theobromine is not as addictive, it has been cited as possibly causing addiction to chocolate .

Theobromine has also been identified as one of the compounds contributing to chocolate's reputed role as an aphrodisiac. 

It affects the heart

As it is a myocardial (heart) stimulant as well as a vasodilator, it increases heartbeat, and also dilates blood vessels, causing a reduced blood pressure.  A 2005 paper published suggested that the decrease in blood pressure may be caused by flavanols.  Its draining effect allows it to be used to treat cardiac failure, which leads to and is exacerbated by an excessive accumulation of fluid in the body. 

Helps against coughing and asthma

A 2004 study published by Imperial College London concluded that theobromine has an antitussive (cough-reducing) effect superior to codeine by suppressing vagus nerve activity. In the study, 1,000 milligrams (0.035 oz) theobromine (equivalent to ~71 grams (2.5 oz) dark chocolate) significantly increased the threshold of capsaicin concentration required to induce coughs when compared with a placebo.  A drug, called BC1036, is being developed by the private UK company infirst Healthcare and it uses theobromine to treat persistent cough. 

Theobromine is helpful in treating asthma, since it relaxes the smooth muscles, including the ones found in the bronchi.

Toxicity for animals

Animals that metabolize theobromine (found in chocolate) more slowly, such as dogs, can succumb to theobromine poisoning from as little as 50 grams (1.8 oz) of milk chocolate for a smaller dog and 400 grams (14 oz), or around nine 44-gram (1.55 oz) small milk chocolate Hershey bars, for an average-sized dog. It should be observed the concentration of theobromine in dark chocolates (approximately 10 g/kg (0.16 oz/lb)) is up to 10 times that of milk chocolate (1 to 5 g/kg (0.016 to 0.080 oz/lb)) - meaning dark chocolate is far more toxic to dogs per unit weight or volume than milk chocolate.

The same risk is reported for cats as well,  although cats are less likely to ingest sweet food, with most cats having no sweet taste receptors. Complications include digestive issues, dehydration, excitability, and a slow heart rate. Later stages of theobromine poisoning include epileptic-like seizures and death. If caught early on, theobromine poisoning is treatable.  Although not usual, the effects of theobromine poisoning, as stated, can become fatal.

The toxicity for birds is not known, but it is typically assumed that it is toxic to birds.

Source: adapted from Theobromine. (2017, February 25). In Wikipedia, The Free Encyclopedia. Retrieved 03:59, March 7, 2017, from