August 1, 2019

expert reaction to study on chocolate consumption and symptoms of depression

Research, published in Depression and Anxiety, reports that consumption of chocolate, particularly dark chocolate, may be associated with reduced odds of having symptoms of depression.

Dr Andreas Reif, Head of Department of Psychiatry, University Hospital Frankfurt, Goethe University, said:

“It should be noted that only a small number of those involved in the study were dark chocolate eaters which may limit how much we can learn from these findings. While the authors attempt to account for many confounders – such as differences between groups regarding age, marital status, household income, education, smoking, BMI –  all of which are associated with depression, it’s very unlikely that ruling out hidden factors that result in more dark chocolate consumption and less depressive symptoms can be achieved fully. Such factors, e.g. a healthier general lifestyle, may well remain unaccounted for differences between those reporting symptoms of depression and those not.

“In addition to this, the study uses PHQ-9 scores which while used to screen for depression, in this study are unable to indicate whether any of the participants actually had depression. These PHQ-9 scores were then used in a binary way (people scoring more/ less than 10 on the PHQ-9 questionnaire) but perhaps it would have been more appropriate to use these scores in a continuous scale.

“Most importantly, this is only an association between current dark chocolate consumption and current depressive symptoms. The most likely explanation is that depressive people eat less dark chocolate and not that having more dark chocolate prevents depression.”

Dr Jane Morris, Consultant Psychiatrist at the Royal College of Psychiatrists in Scotland said:

“It is very welcome that medical science is awake to the crucial role of nutrition in mental as well as physical health.

“However, there are two important cautions.  The first is that we are talking about pure cocoa rather than confectionary that contains some chocolate.  The second is that research suggests an association with depressive symptoms in the general, reasonably healthy population.  It doesn’t suggest that chocolate is a cure for depression.”

Prof Anthony Cleare, Consultant Psychiatrist; Professor of Psychopharmacology and Affective Disorders, Institute of Psychiatry Psychology & Neuroscience, King’s College London (IoPPN), said:

“Although there is an association between lower rates of depression and higher intake of dark chocolate, the main problem with the study is that it cannot tell us whether it is the dark chocolate protecting against depression or whether it is depression affecting the consumption of dark chocolate. We know that depression has marked effects on overall appetite and on the type of foods people crave, and it is just as plausible that the direction of causation is the reverse to the authors’ interpretation.

“It is also just a snapshot of chocolate consumption over 24 hours, reliant on individuals’ memories, and depression has marked effects on impairing memory. Thus, those with depression may have a less accurate recollection of their intake the day before.

“Finally, the amounts of dark chocolate consumed are tiny (10 g, about a tenth of a 100 g bar of chocolate) and this would mean that the biologically active ingredients mediating any effect would need to be having powerfully effects indeed for such a small dose.

“What is really needed are longer term studies that measure dark chocolate consumption over a more prolonged period – more than just a single day – and then measure subsequent depression, in order to tease out cause and effect with more certainty.”

‘Is there a relationship between chocolate consumption and symptoms of depression? A cross‐sectional survey of 13,626 US adults’ by Sarah E Jackson et al. was published in Depression and Anxiety.

DOI: https://doi.org/10.1002/da.22950

Declared interests:

Dr Andreas Reif: I have served on advisory boards of several pharmaceutical companies, but never received compensation from chocolate producers.

Prof Anthony Cleare: Prof Cleare has in the last three years received honoraria for speaking from Lundbeck; honoraria for consulting from Livanova, Lundbeck and Janssen; sponsorship for conference attendance from Janssen; and research grant support from the Medical Research Council (UK), Wellcome Trust (UK) and the National Institute for Health Research. (UK). Prof Cleare works in the same Institution as one of the authors of this paper but was not involved in this piece of work.

None others received