ReviewMood state effects of chocolate
Introduction
If any man has drunk a little too deeply from the cup of physical pleasure; if he has spent too much time at his desk that should have been spent asleep; if his fine spirits have become temporarily dulled; if he finds the air too damp, the minutes too slow, and the atmosphere too heavy to withstand; if he is obsessed by a fixed idea which bars him from any freedom of thought: if he is any of these poor creatures, we say, let him be given a good pint of amber-flavored chocolate....and marvels will be performed. — Anthelme Brillat-Savarin (1755–1826).
Chocolate is cheaper than therapy and you don't need an appointment. — Unknown.
It is commonly claimed that chocolate has the capacity to lift spirits, to create highs and make people feel good. In an earlier review of atypical depression and its constituent feature of hyperphagia (Parker et al., 2002), we noted the capacity of carbohydrates (including chocolate) to have a comforting effect and to also promote ‘feel good’ sensations through the release of multiple gut and brain peptides. Others have argued that carbohydrate craving (including chocolate craving) in atypical depression (Moller, 1992) and in seasonal affective disorder (SAD) (Wurtman and Wurtman, 1989) is a form of self-medication and, in having an impact on brain neurotransmitters have antidepressant benefits.
Publication of our earlier paper (Parker et al., 2002) led to considerable media attention and inquiries both from those with a mood disorder and the general public as to whether chocolate actually was an antidepressant, so encouraging a literature review. Use of the single word ‘chocolate’ in search engines identified an extraordinarily broad literature warranting integration and encouraging the current review. While we had an agnostic view about chocolate having any antidepressant properties, it became apparent that there were many other topic components of equal importance, resulting in this review going beyond the initial simple objective. As noted by one journal assessor, aspects have some significance for our understanding of the biology of depression, and for the concept of ‘atypical depression’ in particular.
In this overview, we consider why people crave and eat chocolate, particularly in the context of food cravings and emotional eating, and chocolate's mood state effects. In the many comprehensive reviews (e.g., Bruinsma and Taren, 1999, Christensen, 1993, Ganley, 1989, Mercer and Holder, 1997, Ottley, 2000, Pelchat, 2002, Rogers and Smit, 2000, Weingarten and Elston, 1990), explanations of chocolate and carbohydrate cravings vary widely and include self-medication, homeostatic correction, hedonic experience, addiction to psychoactive substances and emotional eating theories, but it may be possible to integrate the disparate theories. We will argue that chocolate ‘craving’ and chocolate ‘emotional eating’ are two separate phenomena — although they can co-exist in the same individual — and that any mood state effects of chocolate are as ephemeral as holding a chocolate in one's mouth.
Section snippets
Chocolate composition
Chocolate is manufactured from cocoa mass (the base product produced by the processing of the cocoa bean), cocoa butter (the natural fat from the cocoa bean) and added sugar. Cocoa butter melts at room temperature to provide the creamy “melt in the mouth” sensation. Europeans added sugar to appeal to their palate when chocolate was introduced from America. Dark chocolate contains these three elements, milk chocolate contains extra milk solids and fats, and white chocolate is akin to milk
Chocolate and neurotransmitter systems
Chocolate may interact with a number of neurotransmitter systems (including dopamine, serotonin and endorphins) that contribute to appetite, reward and mood regulation. Some relevant literature is now considered.
From pleasure to aversion: a PET study
Small et al. (2001) undertook successive PET scans on volunteers who ate chocolate beyond satiety. Their research model held the sensory stimulus and act of eating as constant, while motivation to eat and reward value were modified by feeding. Differing structural groups were selectively recruited depending whether chocolate was eaten with pleasure and motivation (subcallosal region, caudomedial orbitofrontal cortex, insula/operculum, striatum and midbrain) as against when satiated
Orosensory properties of chocolate and the pleasure principle
The orosensory properties of food, mediated by palatability, have a significant influence over eating. Moment-to-moment, eating is controlled predominantly by the orosensory effects that provide positive feedback, and the post-ingestive effects which provide negative feedback. Effects in the mouth are stimulatory, while the entry of food into the stomach is inhibitory. Positive feedback is ‘the stimulation of eating by eating’ and its strength is influenced by palatability (Yeomans, 1996),
A homeostatic hypothesis
One view regards craving for chocolate and carbohydrates as a homeostatic response to dietary deficiencies. For example, chocolate craving has also been proposed as a response to a magnesium deficit. However, while a magnesium supplement has been demonstrated to reduce chocolate craving, certain foods high in magnesium are neither craved nor satisfy craving for chocolate (Michener and Rozin, 1994). Further, several studies have failed to establish that dieters do experience any greater craving
Emotional eating
Lyman (1982) has observed that food preference is altered across a range of mood states, with preference for ‘junk food’ increasing during negative mood states and preference for healthy foods increasing during positive mood states. Reviews by Ganley (1989) and Christensen (1993) detail numerous associations between multiple mood states (stress, boredom, depression, loneliness, social self-doubt, discord, frustration, anger and anxiety) and coping by emotional eating (Weintraub and Aronson, 1969
Food craving as addiction
Food craving shares some features with drug addiction, including similar neurotransmitter substrates, and terms such as ‘chocoholic’ and ‘sugar addiction’ are in common use, but there is no consensus that food cravings qualify as an addiction. The psychoactive substances in chocolate lack such propensities, and chocolate cravers classing themselves as ‘chocoholics’ identify the orosensory properties as the ‘addictive’ factor (Hetherington and Macdiarmid, 1993). This interpretation is compatible
An evolutionary perspective
Addiction has been modeled as a cycle of progressively-increasing dysregulation of brain reward systems, resulting in compulsive use and loss of control over drug taking. According to Koob and Le Moal (2001) the normal ‘limitation of reward’ function fails to operate within the normal homeostatic range and forms an allostatic state (i.e., a chronic deviation of the reward set point). An evolutionary model hypothesizes that food craving, overeating and addiction emerge from dysregulation of
Conclusion
For most people chocolate invokes anticipatory and consummatory pleasure, and is therefore an indulgence. When taken in response to a dysphoric state as an ‘emotional eating’ strategy it may provide some transient ‘comforting’ role but it is more likely to prolong rather than abort the dysphoric mood. It is not, as some would claim, an antidepressant.
Acknowledgments
This review was supported by an NHMRC Program Grant (222708) and an Infrastructure Grant from the NSW Department of Health.
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