There is something very special about chocolate – and as long as we remember it is mostly fat, and treat it appropriately, it’s a confection that most of us can enjoy.
Some chocolatiers will tell you that the reason chocolate is so appealing is because of the tactile sensation of consuming it. Because it melts at the temperature of your mouth, the solid turns into a sensuous liquid on your tongue. And there is an element of truth in this. It is also the case that there are a range of active chemicals in chocolate that could influence our brains, and sugar has to be part of the attraction of the modern treat. But there seems little doubt that we also get a kick from a substance called theobromine.
This is a bitter tasting alkaloid, a term we often associate with drugs like morphine and natural poisons. Caffeine, nicotine, quinine and cocaine are all part of the alkaloid family, but none has the appeal of theobromine. A clue might come from the Greek origins of the name which approximate to ‘food of the gods.’ Theobromine is the compound that makes chocolate special. The main source in our diet is the cocoa tree. The seeds of this tree (misleadingly called cocoa beans) contain the fatty substance cocoa butter that is the main ingredient of chocolate.
Chocolate has been enjoyed as a drink in Central and South America for at least three thousand years, and has been popular in Europe since the seventeenth century. In its original form, the drink was bitter (it often had chillies added to give it more bite) – it was a European twist to add sugar and milk to make something closer to modern drinking chocolate. The familiar solid form didn’t arrive until the nineteenth century, which was also when theobromine was first discovered. The substance has similar effects on the brain to caffeine, which is probably why you will occasionally see it said (incorrectly) that chocolate contains caffeine. Theobromine can reduce sleepiness and in large quantities produces a jittery sensation. On the positive side it is a cough suppressant and can help reduce asthma symptoms.
Most of us have heard that chocolate is not good for dogs – and it is theobromine that is to blame. The darker the chocolate, the higher the concentration of theobromine, and the more dangerous it is. A small dog could be killed by as little as 50g of strong dark chocolate. Smaller doses will cause vomiting. This isn’t a problem limited to dogs, poisoning all mammals to some degree, though the speed at which theobromine is disposed of by the system differs from species to species. Cats are particularly sensitive to theobromine, but rarely eat chocolate because they don’t have sweet taste receptors and so don’t get the kick from sweets that humans (and dogs) do.
Theobromine is also poisonous to humans, though not to same the degree as dogs and shouldn’t cause concern. Almost everything is poisonous in a large enough dose (even water, for example) and toxicity is all about dosage. In the case of theobromine, humans have about three times the resistance per kilogram of bodyweight as does a dog, and are significantly heavier, so we are much less likely to be damaged by our treats. A dangerous dose for an adult human would involve eating more than 5kg of milk chocolate.
A number of health benefits have been claimed for chocolate, including reducing blood pressure, reducing stress, reducing diabetes risk and giving limited protection against bowel cancer. None of the trials that have come up with these results have been big enough or repeated sufficiently to be sure of the outcome. The effect on blood pressure was slight, the cancer results are only laboratory based and the stress test was poorly designed (and sponsored by a chocolate manufacturer). The diabetes results were based on compounds in chocolate called flavonoids, but the trial could not show if the flavonoids caused the benefits – and chocolate is not the best source of flavonoids (the study focussed mainly on berries and wine). Plus we know that excess sugar consumption, a major content of most chocolate products, makes diabetes more likely.
[NEW] A recent addition to the chocolate family is 'raw chocolate' which is being promoted as yet another superfood. What this means is that the cacao beans are not roasted as usual, but left outside in the sun to dry. It is claimed that this means there is less loss of nutrients and keeps more antioxidants. As we've seen elsewhere superfood claims are very dubious, and consuming excessive antioxidants seems to be bad for you - so given it has been suggested the raw process could increase the risk of bacterial contamination, there seems little reason to prefer raw chocolate. Eating chocolate for health doesn't make a lot of sense. A good balanced diet is the health part - chocolate is a fun excess.
Bearing in mind the high fat levels in chocolate, the balance of evidence is that that we can’t think of it as a healthy food, but rather one to enjoy in moderation.