The study by University College London (UCL), the University of Calgary and Alberta Health Services Canada, also found that the people who consumed the most of any chocolate were also 57 percent less likely to report depressive symptoms.
Lead author Dr Sarah Jackson, of UCL’s Institute of Epidemiology & Health Care, said: “This study provides some evidence that consumption of chocolate, particularly dark chocolate, may be associated with reduced odds of clinically relevant depressive symptoms.
“Should a causal relationship demonstrating a protective effect of chocolate consumption on depressive symptoms be established, the biological mechanism needs to be understood to determine the type and amount of chocolate consumption for optimal depression prevention and management.”
The study is the first to examine the association with depression according to the type of chocolate consumed.
The team assessed data from 13,626 adults from the US National Health and Nutrition Examination Survey.
A 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 to ensure 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 percent lower odds of reporting clinically relevant depressive symptoms in the previous two weeks than those who reported not eating chocolate at all.
Most recent figures show that around 19.7 percent of people in Britain aged 16 and over showed symptoms of anxiety or depression.
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.
Dark chocolate also has a higher concentration of flavonoids, antioxidant chemicals which lower inflammation and can prevent the onset of depression.
However British scientists urged caution about the findings, suggesting that the decision to eat dark chocolate could be linked to other health factors. For example people who choose dark chocolate may be more health conscious in general, which is known to protect against depression.