Eating dark chocolate may positively affect mood and relieve depressive symptoms, finds a new UCL-led study looking at whether different types of chocolate are associated with mood disorders.
The study, published in Depression and Anxiety, is the first to examine the association with depression according to the type of chocolate consumed.
Researchers from UCL worked in collaboration with scientists from the University of Calgary and Alberta Health Services Canada and 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.
In the cross-sectional study, 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 than those who reported not eating chocolate at all.
The 25 percent 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.
However, researchers found no significant link between any non‐dark chocolate consumption and clinically relevant depressive symptoms.
Depression affects more than 300 million people worldwide, according to the World Health Organisation, and is the leading global cause of disability.
Lead author Dr Sarah Jackson (UCL 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.
“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.
“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.”
Chocolate is widely reported to have mood‐enhancing properties and several mechanisms for a relationship between chocolate and mood have been proposed.
Principally, chocolate contains a number of psychoactive ingredients which produce a feeling of euphoria similar to that of cannabinoid, found in cannabis.
Principally, 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.
Experimental evidence also suggests that mood improvements only take place if the chocolate is palatable and pleasant to eat, which suggests that the experience of enjoying chocolate is an important factor, not just the ingredients present.
While the above is true of all types of chocolate, dark chocolate has a higher concentration of flavonoids, antioxidant chemicals which have been shown to improve inflammatory profiles, which have been shown to play a role in the onset of depression.
Polyphenols are bioactive compounds found in many plants, fruits and vegetables.
The beneficial effects on human health associated with the consumption of a diet rich in polyphenols have generated great scientific interest in these substances.1–3
The action of polyphenols is based on their antioxidant capacity through the uptake of free radicals, the chelation of metals with redox properties and the modulation and inhibition of enzymatic activities.4
The most abundant polyphenols in cocoa are flavonoids, which have been linked to a protective effect against cardiovascular disease, decreasing the risk of cardiovascular morbidity and mortality and favouring the prevention of other chronic diseases, such as diabetes mellitus type 2.1–3 5–7
The ability to reduce cardiovascular risk could be due to an improvement in the elements that define metabolic syndrome, the improvement of vascular endothelial dysfunction, insulin resistance and the inhibition of platelet activation and aggregation.8 9
However, although current evidence suggests that polyphenols produce an improvement in cardiovascular health, this is insufficient to determine the minimum amount of intake necessary to achieve health benefits.10
Cocoa polyphenols and blood pressure
The effect of consuming polyphenols present in chocolate on the blood pressure statistics of healthy individuals is unclear.
Cocoa consumption has been associated with an improvement in endothelial function and a decrease in blood pressure in both healthy subjects and those with risk factors and cardiovascular diseases.11 12
Some studies have observed a dose-dependent relationship between cocoa intake and clinical blood pressure, with higher consumption equated to lower blood pressure and better vascular function.13 14
Conversely, other research has not obtained significant changes in these parameters related to the supplementation of cocoa or pure polyphenols, such as epicatechin or quercetin.15 16
Endothelial dysfunction in postmenopausal women causes changes that favour the development of cardiovascular risk factors and atherosclerosis, which lead to the appearance and maintenance of hypertension.17 18
A decrease in blood pressure has been observed in this group after daily consumption of cocoa with a flavonol content of 40.12 mg. Below this level, however, no changes have been observed.19
Cocoa polyphenols and vascular function
Among healthy individuals, as well as postmenopausal women, the consumption of polyphenols present in cocoa has been associated with a dose-dependent improvement of vascular function, in particular of arterial stiffness measured by pulse wave speed.13 14 19
One of these studies also suggests that the reduction in arterial stiffness observed in postmenopausal women after consumption of cocoa is independent of the frequency of the intake.19
However, this relationship is not evident in people with mild hypertension when cardio-ankle vascular index (CAVI) is used as a measure of arterial stiffness.20
There is also evidence of the influence of these polyphenols in reducing the augmentation index (AIx).
The study by West et al,21 involving subjects with excess weight and moderate obesity, concludes that treatment with dark chocolate decreases AIx in women, although it seems that this association might have a greater effect on the elasticity of the large arteries, especially in subjects with obesity and diabetes mellitus type 2.22
Cocoa polyphenols and cognitive performance
There is evidence to suggest that chocolate rich in polyphenols is beneficial for cognitive performance and state since it improves mental processing speed and attenuates the increase of mental fatigue among healthy young adults.23 24
An improvement in cognitive performance among older age groups after eating chocolate has also been observed,25 especially in subjects with higher risk of cardiovascular disease.26
Several studies also show that polyphenol-rich chocolate causes an improvement in executive function, categorical fluency27 and working memory,28 29 and a slowing of mental fatigue.30
Also, a higher frequency of chocolate consumption has been associated with improved cognitive function.29
Furthermore, a positive influence of cocoa polyphenols on physiological processes has been reported, with a neuroprotective effect31 and improved cognitive performance.32
In this regard, it has been suggested that the brain-derived neurotrophic factor plays a role in the cognitive enhancement induced by the flavonoides.33 Favourable effects on cerebrovascular function have also been observed in postmenopausal women after consumption of chocolate with a high concentration of cocoa.34
Cocoa polyphenols and quality of life
The quality of life linked to health is represented by the individual’s perception of well-being in various aspects of life, including physical and mental aspects.
The effect of chocolate and polyphenols on the quality of life has scarcely been studied, with little available evidence and even less of a conclusive nature. In a study conducted among healthy people, where regular consumption of chocolate was recorded over 1 year, no evidence was found of a clear association between chocolate intake and the physical or mental components of quality of life.35Nevertheless, it has been observed that the consumption of dark chocolate might be beneficial for the quality of life of women with fibromyalgia.36
Cocoa polyphenols and body composition
The menopause period leads to various changes in the body composition of women.37 Regarding the connection between cocoa polyphenols and body composition, results diverge. Some clinical trials involving healthy people and overweight or obese patients have not reported significant differences that link chocolate consumption to anthropometric measures.16 20 21 38
Other studies indicate that chocolate consumption might have positive effects on body composition in adolescents,39patients with diabetes40 or women with obesity.41
Two recent systematic reviews also indicate that eating chocolate is associated with reduced body mass index (BMI) and waist circumference,42 43 and one of them also concludes that the amount and the length of time during which it is eaten play a key role in these beneficial effects.43 Conversely, other studies such as that carried out with the cohort of the Atherosclerosis Risk in Communities study have observed a dose-dependent increase in weight after habitual chocolate consumption.44
In sum, the polyphenols present in chocolate seem to have a positive effect on blood pressure, vascular function, cognitive performance and quality of life, especially in populations with increased cardiovascular risk, such as postmenopausal women.45
However, the conflicting results obtained in different studies suggest that the real contribution of these compounds to health and the underlying mechanisms remain unclear. Moreover, most of these studies have used preparations with high concentrations of polyphenols that are usually not present in the normal diet.
This study aims to evaluate the effect of adding a daily amount of 10 g of chocolate high in cocoa content (99%) and polyphenols to the normal diet on blood pressure, vascular function, cognitive performance, quality of life and body composition in postmenopausal women.
Source:
UCL
Media Contacts:
Chris Lane – UCL
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The image is in the public domain.
Original Research: Closed access
“Is there a relationship between chocolate consumption and symptoms of depression? A cross‐sectional survey of 13,626 US adults”. Sarah E. Jackson, Lee Smith, Joseph Firth, Igor Grabovac, Pinar Soysal, Ai Koyanagi, Liang Hu, Brendon Stubbs, Jacopo Demurtas, Nicola Veronese, Xiangzhu Zhu, Lin Yang.
Depression and Anxiety. doi:10.1002/da.22950
