{"id":971,"date":"2019-12-02T18:16:56","date_gmt":"2019-12-02T18:16:56","guid":{"rendered":"https:\/\/research.reading.ac.uk\/herbarium\/?p=971"},"modified":"2019-12-09T18:44:38","modified_gmt":"2019-12-09T18:44:38","slug":"adventbotany-day-2-death-by-chocolate","status":"publish","type":"post","link":"https:\/\/research.reading.ac.uk\/herbarium\/2019\/12\/02\/adventbotany-day-2-death-by-chocolate\/","title":{"rendered":"#AdventBotany 2019 Day 2: Death by chocolate"},"content":{"rendered":"

By Alastair Culham<\/a><\/h1>\n

\"A<\/a><\/p>\n

In 2014 I introduced the food of the gods, Theobroma cacao,<\/em> as the source of chocolate, that staple of Christmas excess, in the 16th Advent Botany post<\/a>.\u00a0 Today, in the second for 2019, I explore Theobromine<\/strong>, perhaps the best known chemical compound in chocolate, and one of the many chemicals that make it so popular.<\/p>\n

Theobromine, is a xanthene alkaloid like caffeine, and is formed during the metabolic breakdown of caffeine, as well as ocurring naturally in cocoa and some other plants.\u00a0 It reduces sleepiness by blocking adenosine receptors, it dilates blood vessels and relaxes smooth muscle tissue in the lungs.\u00a0 The effects are long-lasting with a half life of around three hours in humans and it has been shown to have a mood improving effect.\u00a0 This contrasts with 5-6 hours half life for caffeine.<\/p>\n

\"Ball<\/a>
Ball and stick models of Caffeine (left) and Theobromine (right). Carbon = black; Nitrogen = blue; Oxygen = red; hydrogen = white.<\/figcaption><\/figure>\n

Theobromine can be toxic in high concentrations (Finlay & Guiton, 2005) but the LD50<\/sub> (median lethal dose) is around 0.5-1 gram per kilo of body weight so a 70 kg (11 stone) adult would need to eat 35-70g of Theobromine (ca 10kg of dark chocolate) to be fatal.<\/p>\n

\"A<\/a>
Dark chocolate (Photo: jackmac34 (pixabay.com))<\/figcaption><\/figure>\n

Before that, the vomiting and diarrhoea of Theobromine toxicity would have cut in.\u00a0 This is conjecture, of course, as the estimates are based on experiments with rats.\u00a0 Human experiments have not been conducted.\u00a0 I could find no reported case of death by chocolate in humans.\u00a0 In cats and dogs the lethal dose is lower (ca 0.3g Theobromine per kg body weight) and they metabolise the theobromine more slowly (a half life of 18 hours has been reported) so 2 kg of chocolate could deliver the fatal dose to a small dog.\u00a0 Again, the symptoms of the toxicity are likely to clear the chocolate from the system before that point is reached.<\/p>\n

Of course, if you have an allergy to chocolate there could well be something other than Theobromine that is bad for you.\u00a0 There are many reports of the symptoms of chocolate allergy but little agreement on the causative agent, especially given that commercial chocolate bars are a complex of many ingredients (NYASC, undated).\u00a0 Groce (2019) suggests that allergy directly to chocolate is very rare and that the symptoms are more likely to be caused by other ingredients in most cases of adverse reaction.<\/p>\n

So, please enjoy your chocolate sweets over the Christmas period but don’t over-eat!<\/p>\n

References<\/h2>\n

Anon Does Chocolate contain drugs? — Molecules found in Chocolate<\/a>, The Science of Cooking<\/a> (Accessed 31st November 2019)<\/p>\n

Finlay, F., & Guiton, S. (2005). Chocolate poisoning<\/a>. BMJ : British Medical Journal<\/i>, 331<\/i>(7517), 633.<\/p>\n

Groce, V. (2019). Is It Possible to Be Allergic to Chocolate? www.verywellhealth.com<\/a><\/p>\n

NYASC, (online) Chocolate Allergy<\/a> (accessed 9th December 2019)<\/p>\n","protected":false},"excerpt":{"rendered":"

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