Cocoa is used in many food product because of its popular taste, the most well known product being chocolate. Cocoa powder is a complex mixture of a number of different biologically active chemicals, some of which have been shown to be beneficial for health. For example, the proanthocyanidins present in cocoa powder have been shown to inhibit platelet aggregation in humans, and regular consumption can protect from cardiovascular disease. Cocoa powder also contains phenylethylamine and serotonin, chemicals that are thought to interact with receptors in the brain ands elicit behavioural changes. Cocoa is also a good source of caffeine and theobromine, two related methylxanthine chemicals that can increase metabolic rate, improve athletic performance and improve short term cognitive ability. Also present are cannaboid-like fatty acids that may interact with endorphin receptors located in the human brain.
Because of the complexity of the chemicals mixture within cocoa, the metabolic effects of ingestion are not fully understood. However, as well as effects on behaviour and the brain, it appears that cocoa is able to increase insulin release in response to food. Research published in the Journal of Nutrition in 20031, fed a variety of foods to subjects and measured the plasma insulin response. Although the glycaemic index of the food did not differ between the food, the insulin released by the subjects was increased in the cocoa containing foods, compared with identical non-cocoa containing alternatives. The greatest difference occurred when flavoured milk was fed to subjects, and the insulin response to the cocoa containing version was 45 % larger than the control. Overall, the cocoa containing food produced an average 28 % increased insulin response.
The results of this study are interesting as the effect of cocoa on insulin release has not been specifically studied previously, although similar effects have been noted. Chemicals within cocoa appear to be able to increase insulin release but do not alter the glyceamic index of the foods, as measured by a 120 min plasma glucose response curve. The exact physiological relevance of an increased insulin response without a corresponding change in glucose levels is not fully understood. However, it is possible that as well as increasing insulin release, cocoa is also able to improve insulin sensitivity. This would explain the lack of a change in the glycaemic response to ingestion. A paper published in the American Journal of Nutrition in 2005 supports the hypothesis that cocoa is able to improve insulin sensitivity2 in otherwise healthy adults.
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