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Chocolate Myths

Caffeine theobromine

A recent front page item on the social bookmarking site Digg.com (click here to find out why bloggers should avoid Digg) made a quite astounding claim. Apparently, “Chocolate does not contain caffeine,” it said. The link is tied to an introductory paragraph that says: “There is a persistent urban legend that chocolate contains caffeine. It would seem that this rumor is based primarily on a confusion between two similar alkaloids: caffeine and theobromine. Theobromine is the active ingredient in chocolate and it occurs only in [the plant Theobroma cacao. The two stimulants are related and have a similar structures.”

Yes, they most certainly do,theobromine (not in anyway related to the element bromine by the way) and caffeine are essentially the same structure but in the caffeine molecule the hydrogen atom on a nitrogen atom in theobromine has been swapped for a methyl (CH3) group. Why is this important. Well, the difference in chemical and biological activity of two molecules that can differ by a couple of hydrogens and a carbon is astounding. More on that later. What about the site’s claims that chocolate does not contain caffeine?

Well, to quote from the page, which was last updated in “late 2001″, “There is no scientific substantiation that chocolate contains caffeine, and a great deal of evidence that it does not. The Biochemist, (Apr/May 1993, p 15) did chemical composition tests where they specifically distinguished between Caffeine and Theobromine. They found regularly up to 1.3% by weight Theobromine in Chocolate. They also found other pharmacologically active compounds including up to 2.20% Phenylethylamine up to 1.54% Tele- methylhistamine and occasionally up to 5.82% Serotonin. They could not detect any Caffeine at all.” [I don't understand why they insist on capitalising "Chocolate, or any of the chemical names, db]

It is possible that this held true in late 2001, but science moves on. A quick search on PubMed plucks out several papers all of which have carried out analyses of chocolate to demonstrate that it does indeed contain caffeine. As just one example, in 2006, German researchers Stark, Bareuther, and Hofmann of the German Research Institute for Food Chemistry, in Garching, provided a molecular definition of the taste of roasted cocoa nibs (Theobroma cacao) by means of quantitative studies and sensory experiments. In their paper they state: “theobromine and caffeine…were among the key compounds contributing to the bitter taste of roasted cocoa.” Their tests were carried out using solvent extraction, gel permeation chromatography, and reversed-phase high-performance liquid chromatography (RP-HPLC) and corroborated earlier findings. The actual quantity of caffeine in chocolate is very small, especially compared with the amount of theobromine.

To quote the UK’s Institute of Food Research on the subject of caffeine in chocolate:

“Chocolate contains bio-active compounds, e.g. caffeine and theobromine. Caffeine is only present in small amounts in chocolate – in fact, one would have to eat about eight 100-gram bars of milk chocolate to consume the amount of caffeine present in a cup of coffee. Theobromine is related to caffeine, and is present in chocolate in much higher amounts, although it has relatively weak stimulant effects. It is possible that in combination, these and other potentially bio-active constituents do influence our liking for chocolate. At present, however, there is no direct evidence to support this.”

But, why should we worry about the presence of caffeine in chocolate or any other food product, and why does this site apparently have such an objection to the fact that chocolate contains caffeine? Caffeine is a bitter-tasting alkaloid, a natural product, a xanthine, found in several plant species, coffee, tea, and cacao. It is a stimulant, like its close chemical cousin, theobromine. There have been dozens of media articles, purportedly based on solid research, that send out mixed messages regarding the health effects of caffeine on people and whether or not we should expose our bodies to this stimulant. It seems that this page is somehow trying to provide a rationale for not avoiding chocolate on the grounds that whatever negative health connotations there are for ingesting caffeine, chocolate will not be a problem…

A quick search of the web for cacao theobromine and caffeine reveals several sites warning of the toxicity of stimulants in chocolate, coffee and other products. But, an NIH page also appears that says something along the line of caffeine content need only be reported if levels are above a certain threshold. Could it be that the author of the xocoatl.org picked up on this fact and has extrapolated the notion of an unreported low level to meaning “none”? Who knows? That said, some chocolate bars do in fact report their caffeine content. Why would a manufacturer do that if they were not obliged to and if it might have a detrimental effect on their sales?

Step back in your browser from the caffeine page, and you will notice that it is hosted on a domain called “xocoatl.org”. Obviously, not a problem in itself, but what is this mysterious organisation that takes its web address from the Aztec word for bitter water (chocolate in other words, modern chocolate only tastes sweet because of the addition of sugar and is nothing like the coffee-like drink thought to have been consumed by the Aztecs).

The root page of xocoatl.org says it is “mrk.’s Chocolate site”, which was apparently created in November 1997 and last updated September 2002 and has “invalid security” according to a prominent link to the well-known statcounter.com site. Intriguingly, it provides a link to mrk.land, which tells us, “some content somewhat organized”, and displays a javascript error below the phrase: “Cost to US Taxpayers of of Bush’s Illegal Invasion of Iraq”. None of which fills me with confidence in reading the preceding pages. That said, there do seem to be several valid facts elsewhere on the site, although I wouldn’t trust their currency given the initial claim highlighted by Diggers. And this brings me back to the original issue? Why should a site that makes an apparently unfounded claim about the lack of caffeine in coffee last updated in late 2001 suddenly be given a kind of credence by making it to the home page of Digg.com? Very odd.

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