For the study, researchers assessed data from 13,626 adults from the US National Health and Nutrition Examination Survey. Participants' chocolate consumption was assessed against their scores on the Patient Health Questionnaire, which assesses depressive symptoms.
Range of other factors including height, weight, marital status, ethnicity, education, household income, physical activity, smoking, and chronic health problems were also taken into account in this cross-sectional study. The study only measured chocolate's effect on depressive symptoms.
After adjusting for these factors, it was found that individuals who reported eating any dark chocolate in two 24-hour periods had 70 per cent lower odds of reporting clinically relevant depressive symptoms than those who reported not eating chocolate at all.
The findings revealed that 25 per cent of chocolate consumers who ate the most chocolate (of any kind, not just dark) were also less likely to report depressive symptoms than those who didn't eat chocolate at all. It must be noted that researchers found no significant link between any non-dark chocolate consumption and clinically relevant depressive symptoms.
"This study provides some evidence that consumption of chocolate, particularly dark chocolate, may be associated with reduced odds of clinically relevant depressive symptoms. However further research is required to clarify the direction of causation it could be the case that depression causes people to lose their interest in eating chocolate, or there could be other factors that make people both less likely to eat dark chocolate and to be depressed," said the lead author of the study, Dr Sarah Jackson.
Several studies have reported about the mood-enhancing properties of chocolate. Chocolate contains a number of psychoactive ingredients, which produce a feeling of euphoria similar to that of cannabinoid, found in cannabis. It also contains phenylethylamine, a neuromodulator which is believed to be important for regulating people's moods.
Evidence also suggests that mood improvements only take place if the chocolate is palatable and pleasant to eat. While the above is true for all types of chocolate, dark chocolate has a higher concentration of flavonoids, the group of antioxidants that help reduce risk of inflammation, which have been shown to play a role in the onset of depression.