Chocolate on trial summary

Chocolate on Trial brings to life the age-old conflict between economic interests and regard for the dignity of human life. Permission to reprint Permission to photocopy or include in a course pack via Copyright Clearance Center. Click or tap on a subject heading to sign up to be notified when new related books come out.

Release date: January pages Rights: World. Rights: World. The first decades of the twentieth century were years of dramatic change in Zanzibar, a time when the social, economic, and political lives of island residents were in incredible flux, framed by the abolition of slavery, the introduction of colonialism, and a tide of urban migration.

In our time, we require a religion, ethics, and politics adequate to confront the global crises we face. We might also look to the older disciplines of religion and ethics to determine our values and to tell us what we ought to do.

The abolition of the slave trade is normally understood to be the singular achievement of eighteenth-century British liberalism.

Abolitionism and Imperialism in Britain, Africa, and the Atlantic expands both the temporal and the geographic framework in which the history of abolitionism is conceived. Firstly, only of patients with acute calculous cholecystitis initially assessed were eligible for inclusion in the study based on inclusion and exclusion criteria. As such, the findings are drawn from 18 percent of patients with this presentation and are therefore open to considerable selection bias.

This finding seems inevitable when comparing cholecystectomy to non-cholecystectomy, although we do note that elective routine cholecystectomy is excluded from the re-operation statistics. In contrast, the rate of acute cholecystectomy conversion to open or primary open procedure in the prospective multicentre CholeS study was 7. In summary, this study will certainly not change practice at our centre.

Only research in which an appropriate placebo or control group was compared to one or more active treatment group s was included. Studies using standardized outcome measures of both mood and cognitive performance were included. Studies examining quantitative measures of cognitive function alone were considered. For studies of mood, experiments employing both quantitative and qualitative measures were examined. LO performed the initial data extraction, and the data were independently checked and audited by AS.

The search of PubMed for human clinical trial studies retrieved articles. PsycINFO generated articles. Web of Science generated articles. There were a total of articles; of these, were duplicates.

A number of articles were also related to caffeine, and a few articles also used chocolate-flavored foods or drinks as a vehicle for other drugs.

In total, articles were clearly not relevant to the subject area and were rejected on the basis of the title and abstract. Of the remaining articles, 75 were related to eating behaviors, 49 were related to mechanisms of action, and 21 were related to mood and cognitive function 4 of which were included under both mood and cognition categories.

Of the 21 articles identified, 12 articles included measures of cognition and 13 included measures of mood. Four of the articles measured both mood and cognition, so these were included in both categories. Of these, eight that measured mood and five that measured cognition one covering both categories did not meet the inclusion criteria. Table 1 summarizes the characteristics of the excluded studies related to mood 12 , — 18 and cognitive function. Figure 1 shows the flowchart for the systematic review.

Flowchart showing numbers of articles at each stage of the search. Footnote a, b, and c include 5, 1, and 3 articles, respectively, describing studies that examined both mood and cognitive outcomes. Reasons for exclusion of studies that examined associations between chocolate and mood and between chocolate and cognition. Summary of studies examining the effects of chocolate, cocoa, or theobromine on mood. Summary of studies examining the effects of chocolate, cocoa, or theobromine on cognitive and neurocognitive function.

The search of PubMed for reviews and meta-analyses used the same search terms as the original search, but the limit was set to reviews and meta-analyses. This search generated articles, of which 26 were potentially relevant. This search revealed 11 articles, of which 2 were potentially relevant. In Web of Science, when the search was restricted to literature reviews, 6 articles were identified, 2 of which were potentially relevant.

A total of 30 reviews were identified. Each of the selected articles was analyzed for methodological quality using a modified augmented Jadad scale, 23 as first developed by Sarris and Byrne. The modified version used for this review is a point scale that assesses the following additional methodological factors: 1 Was the study described as randomized?

Affirmative answers were given one point, and negative answers received no points; thus, the maximum possible rating was 10 points. The modified Jadad scale is extremely prescriptive, so there was very little disparity between the two raters. In fact, ratings differed for only two articles by 1 point in each case , and these differences were resolved upon reinspection of the articles.

Overall the cognitive studies had a higher quality rating ranging from 7 to 10; median 8 than the mood studies range 5 to 9; median 6. There is a large body of research examining the effects of chocolate as a mood-enhancing agent as well as several plausible hypotheses for the possible effects of how food may produce a comforting or mood-ameliorating effect.

Several inclusive reviews explored eating behavior in relation to chocolate. A complete review of the literature on eating behaviors is beyond the scope of this systematic review, but the uniqueness of chocolate as an often highly craved food merits some attention. Chocolate is the most commonly craved food, and, for most chocolate cravers, nonchocolate substitutes are inadequate. Potential psychoactive ingredients of chocolate have been evaluated in this context largely because chocolate craving appears to share some features with addiction.

Several candidates have been identified e. However, several authors have argued that these substances are present in concentrations are too low to have a significant psychoactive effect and, moreover, they are also present in higher concentrations in other noncraved foods.

The prevailing view is that cravings can be explained fundamentally by the following specific orosensory qualities of chocolate: highly palatable, very sweet, and produces an optimal mouthfeel. It seems likely that the desire for chocolate arises from the unique flavor and synergistic relationship among its components. For example, milk chocolate appears to be the most preferred by subjects when milk chocolate, dark chocolate, white chocolate, and cocoa powder powdered cocoa mass with some cocoa butter extracted are compared.

If cravings are elicited solely by psychoactive substances within chocolate, then cocoa powder should satisfy craving and dark chocolate should be the most preferred. Other authors have also discussed the possibility of dopaminergic and opioid activity after chocolate consumption. Drewnoski 35 has argued that carbohydrate craving is more strongly linked to the opioid system. Since then, Mercer and Holder 36 have proposed an opioidergic theory of food craving.

Chocolate and cocoa contain the unsaturated N -acylethanolamines N -oleoylethanolamine and N -linoleoyl ethanolamine , which are chemically and pharmacologically related to the endogenous cannabinoid anandamide. Again, it is possible that the concentration of anandamide analogs in chocolate is insufficient to induce these neurochemical effects.

There appear to be several reasons why humans enjoy ingesting chocolate, and it is clear that, for many individuals, the particular combination of constituents may be specifically and uniquely craved.

A number of potential psychomodulating mechanisms have been proposed, but the general consensus among the research community is that, while many psychoactive substances are present in chocolate, the amounts of these substances at least in the forms of chocolate consumed today are relatively small and are unlikely to cause behavioral modulation.

A large body of research has demonstrated that individual factors may have specific influences on chocolate craving. In this systematic review, evidence for effects on mood has been drawn only from research in which 1 a reported amount of chocolate or components of chocolate was ingested; 2 mood was measured as an outcome variable following chocolate ingestion; 3 an adequate control condition was employed; 4 statistical comparison between chocolate and control was conducted; and 5 quantitative measures of mood were used.

Following a literature search, a total of 14 relevant articles in which chocolate was consumed and mood was measured as an outcome variable were identified.

These studies are discussed and appraised in detail below. Furthermore, some of the studies that were not considered to meet the inclusion criteria are also noted for their relevant contributions. Several studies that were identified in the literature search examined the effect of chocolate on mood outcomes following experimentally induced mood states.

In this experiment, learned helplessness was induced by using an unsolvable task. A total of five groups were used in a parallel group design.

In one group control group , the participants were not primed with the impossible task for learned helplessness and were not given any intervention. Four other groups were exposed to the learned-helplessness task, after which chocolate, exercise, guided imagery, or nothing was administered. All participants in each of the five groups were then given the solvable task.

All interventions exercise, chocolate, and guided imagery appeared to ameliorate this effect to a level similar to that observed in the control group. For those who attempted the unsolvable task and were not given an intervention, anxiety levels remained unaltered. Perhaps in the case of learned helplessness, simply having any form of intervention compared with none is perceived as having increased control, thereby contributing to the observed reduction in anxiety.

Three studies by Macht et al. Like the study of Weisenberg et al. The authors attempted to induce states of anger, fear, sadness, or joy by presenting emotive film clips to the participants.

Unfortunately, this study did not employ a control condition for comparison, so it could not be included as part of the systematic review. Macht and Mueller 49 did, however, conduct a further study in , in which mood states were again experimentally induced using film clips to emote feelings that were sad, happy, or neutral.

Mood was measured on a point scale that was subdivided into five categories very good, 21—25; good, 16—20; medium, 11—15; bad, 6—10; very bad, 1—5. The participants were instructed to first decide on their mood and then on the numerical gradation within that category e. In this study, two experiments were conducted. The first aimed to examine the immediate effects of chocolate consumption on mood. Specifically, it was hypothesized that eating chocolate would impact the mood of an individual when a negative mood had been induced, but not when a positive or a neutral mood had been induced.

The authors confirmed this hypothesis, showing that negative mood was reduced in the chocolate eaters compared with the water drinkers. A second experiment compared the effects of eating palatable versus unpalatable chocolate on negative mood in order to ascertain whether a reduction in negative mood was due to a physiological effect of the chocolate or to the palatability of the chocolate.

Although this study did not meet the inclusion criteria for the present review, largely because the outcome variables were biological rather than behavioral, it is worth mentioning here.

Biological fluids were collected during 3 test days at baseline, on day 7 mid trial , and on day 14 end of the trial. The authors themselves concluded that these markers of stress and metabolism may be modified through the actions of gut microbial activities and that administration of whole dark chocolate improves the activity of the symbiotic bacterial partners. A further investigation by Macht and Dettmer 48 evaluated the effect of chocolate on mood, but this time in the absence of an induced negative mood.

In this experiment, the notion that mood effects may be transient and due to simply ingesting a sweet snack was investigated. Mood was examined following ingestion of a chocolate bar, an apple, or nothing. Participants in the chocolate group also experienced greater feelings of guilt.

No effects of individual constituents of chocolate can be inferred. In the studies by Macht and Dettmer 48 and Macht and Mueller 49 that are included in this systematic review, there is some disparity regarding the length of time these effects of chocolate on mood persist. The observed effects of chocolate on mood in these studies seems likely to implicate the pleasurable consequences of consuming chocolate and the potential activation of reward pathways in the brain, as discussed above in the context of oral detection of the carbohydrate saccharin.

The effects of chocolate on mood and cognition have been theorized to be due to specific constituents of MXs e. A few of the studies that were identified in the literature search have examined altered concentrations of these active ingredients in order to discern any selective benefit provided by individual components of chocolate.

They describe two double-blind, placebo-controlled studies that measured the effects of cocoa powder versus MXs administered in opaque capsules MX content equivalent to that of a g bar of dark chocolate on cognitive performance and mood. In the first study, participants received Participants completed a test battery once before and twice after treatment administration. Mood was measured using a item visual analog scale that was devised from other validated mood measures.

Hedonic tone was also improved by both of the active treatments, although this effect reached significance only with the caffeine-theobromine combination. These amounts are typically present in white, milk, and dark chocolate, respectively. Energetic arousal and hedonic tone again appeared to be greater following low and high doses of MX compared with water and zero-MX treatments, but this effect failed to reach significance.

While the behavioral effects of caffeine have been well documented, those of the other major cocoa MX, theobromine, have been more tenuous. In fact, the lack of theobromine effects in preclinical behavioral research had previously led some authors to conclude that theobromine was behaviorally inert. Only a few studies have examined the behavioral effects of theobromine in isolation. This study did not meet the inclusion criteria for the present systematic review because of the small sample size of seven subjects.

Nevertheless, it showed that five of the seven subjects were able to discriminate a high dose of theobromine from a placebo or caffeine dose. The combination of caffeine and theobromine had effects similar to those of caffeine alone on mood, except for the absence of blood pressure effects.

The authors concluded that theobromine and caffeine could have differential effects on mood and blood pressure. It was tentatively concluded that caffeine may have more central-nervous-system-mediated effects on alertness, while theobromine may be acting primarily via peripheral physiological mechanisms. Another potential active mood modulator in chocolate might be the CF. The authors stated that the mechanisms of action in this trial may have been related to the potential vasoactivity of CF components on endothelial function and blood flow.

In summary, the data appear to demonstrate very reliable effects of chocolate and chocolate components in attenuating negative mood, i. This suggests such effects are derived from a combination of taste, texture, carbohydrate, and fat content rather than from individual psychoactive components or combinations thereof. However, some research has begun to examine the components of chocolate in order to discern any particular active constituents.

Thus far, the evidence reviewed suggests that MXs particularly caffeine may have a role in the mood-altering effects of chocolate, particularly by increasing alertness, although it should be noted that the MX theobromine is also capable of conferring negative mood effects, including reductions in self-reported calmness. The total number of studies that could be considered for evaluation was only six.

Considering the large body of research conducted to evaluate the effects of chocolate, there is clearly a scarcity of data available to answer the questions of whether, how, and for how long chocolate consumption affects mood. Additionally, neither publication bias nor the possibility that nonsignificant findings may be less likely to be published can be excluded.

Epidemiological evidence supports the notion that long-term flavanol intake provides a number of health benefits, including neurocognitive enhancement and neuroprotective effects.

A number of reviews in this area are recommended but are not scrutinized in detail here. Following a literature search, a total of 12 relevant articles in which chocolate was consumed and cognition was measured as an outcome variable were identified.

Furthermore, some of the studies that did not meet the inclusion criteria are noted for their relevant contributions. Of the articles met the inclusion criteria, all examined the cognitive effects of potentially psychoactive fractions of chocolate. Five studies focused on CF fractions of cocoa 56 , 61 , — 64 and three from two articles on combinations of the MXs caffeine and theobromine.

On day 5 they underwent cognitive testing and fMRI. The cognitive assessment consisted of an attentional task in which letter-number pairs were presented in red or blue font. The task involved attending to the color of the font that signaled whether the letter red or digit blue was to be attended to. Despite increased cerebral blood flow CBF and cortical activation following CF administration, there was no enhancement in task performance. Such a task might be expected to be sensitive to CF.

It is therefore possible that performance was already at asymptote, thus minimizing the possibility of detecting enhancement of task performance associated with CF administration. There were no effects of treatment on cognitive function, nor were there changes in a range of physiological or other biomarkers measured at the 3-week midpoint or the 6-week endpoint assessment. While these findings might suggest a lack of effect of CF procyanidins on cognition, there are a number of possible methodological reasons for the negative results.

The authors themselves acknowledge the possibility that the cohort habitually consumed a flavonoid-rich diet. In addition, members of the cohort were cognitively high functioning, which decreased the likelihood of enhancement. It is notable that the cocoa condition was associated with a significantly increased heart rate at both the 6-week endpoint and the 3-week interim assessment, suggesting the treatment was bioactive and imparted physiological effects over and above the habitual diet.

The authors suggest this may be attributable to the MXs caffeine and theobromine present in cocoa products, although this cannot be determined from the study.

As in the study by Francis et al. Behavioral measures of accuracy and reaction time did not differ between treatment groups. The lack of effect on task performance is unsurprising, since the study was designed so that SWM was an activation task only. Two studies that met the inclusion criteria for the present review investigated the acute effects of CF administration.

The authors point out that the greatest number of — and the most significant — effects on mood and cognition were observed during the fourth Cognitive Demand Battery cycle, which coincided with the 2-h peak CBF reported by Francis et al. Thirty healthy young adults took part in a crossover study.

Outcome measures included contrast sensitivity the point at which subjects could no longer distinguish between stimuli of increasingly similar luminance and motion coherence threshold the proportion of coherently moving dots required for subjects to detect them in an array of randomly moving dots.

Participants also underwent two cognitive tests: an SWM task and a two-choice reaction time task. The latter had two phases — a block of predictable stimulus responses alternating Y-N responses and an unpredictable phase that also included a response inhibition element. Both visual contrast sensitivity and motion sensitivity were improved in the high-CF group. There were also significant improvements in aspects of the cognitive tasks.

The high-CF condition was associated with significantly better SWM accuracy and significantly faster choice reaction time during the predicable sequences only. Several studies have examined the cognitive effects of the major MXs, caffeine and theobromine, found in chocolate. The study employed a placebo-controlled, four-period crossover design. Cognitive outcomes were scored using a computer-adapted version of the DSST and the Emotive Reaction Time Test which also served as an implicit mood measure.

The Motivation and Workload Questionnaire was also administered to gauge the level of effort required to perform the tasks.

The effects on mood followed the predicted pattern. Mean response times fastest to slowest are presented as follows: placebo, 2, milliseconds; caffeine-theobromine combination, 2, milliseconds; theobromine alone, 2, milliseconds; caffeine alone, 2, milliseconds.

Smit et al. The first aimed to compare the effects of whole cocoa powder with the effects of MX content only. The effects of Cognitive outcomes were measured using a variable-interval simple reaction time SRT task, the Thurstone tapping task of manual dexterity and psychomotor speed, and the RVIP task. It appears that the effects were more pronounced for the MX treatment than for the cocoa powder.

A second study reported in the same article examined the effects of two doses of MXs on the same tasks. A water control was also included. The results revealed a dose-response effect on SRT performance, with significant effects at the highest dose only, and with more significant effects on RVIP performance at the higher dose than at the lower dose.

The authors conclude that the MXs are the psychoactive components of chocolate. This contention is partially supported by the findings of Mitchell et al. Future studies directly comparing the effects of caffeine, theobromine, and CF, both alone and in combination, might be useful.

There is growing evidence of improved cognitive function with acute administration of CF and MXs. In summary, the literature on the neurocognitive effects of chocolate and its components shows that, despite seemingly strong evidence from epidemiological studies, no study has found cognitive effects in randomized controlled trials using subchronic or chronic administration.

Dosing regimens have included 5 days, 64 30 days, 61 3 weeks, and 6 weeks. There is evidence that certain physiological processes underlying cognitive function are affected, including CBF 62 , 64 and region-specific brain activation. The exact mechanisms by which components of chocolate may benefit cognitive processing remain unknown. The following section briefly describes potential processes that might plausibly benefit neurocognition, most of which have focused on CF.

Dietary intervention trials have shown that the consumption of flavanol-rich cocoa products can lead to changed patterns of neural activity, improved insulin sensitivity, 66 lowered blood pressure, 67 reduced platelet aggregation, 68 and improved endothelial function 69 and blood flow 66 , 70 , — 74 ; the role of antioxidant activity will also be briefly considered.

Compared with a control condition, CF administration resulted in higher levels of task-associated brain activation in the dorsolateral prefrontal cortex, the anterior cingulate cortex, and the parietal cortex.

The participants had ingested CF on the day of assessment day 5 of the subchronic trial , thus the results did not preclude the possibility of acute effects on cerebral metabolism. The primary outcomes were changes in the amplitude and the phase of the SSVEP response, both of which were compared between treatment groups at baseline and after 30 days.

Both SSVEP amplitude and phase were significantly different between groups at posterior parietal and centrofrontal sites during memory encoding, the working memory hold period, and retrieval. These areas constitute a parietofrontal circuit that is reliably activated during working memory tasks. These differences can be interpreted as evidence of greater neural efficiency associated with CF consumption during working memory operations.

These neuroimaging studies demonstrate that CF or their metabolites are bioactive and centrally active and can influence cortical activity both acutely and after long-term day administration. It is commonly believed that many of the health benefits of CF are due to their antioxidant properties.

It is now widely accepted, however, that these ex vivo effects may not translate to in vivo antioxidant properties for reviews, see Frei 75 and Halliwell It is now known that flavanols undergo extensive biotransformation following ingestion, resulting in compounds with greatly diminished antioxidant capacity. An antioxidant role has yet to be substantiated in biological systems using physiologically realistic levels of orally administered CF.

Furthermore, it should be noted that any effects of CF on antioxidant capacity, if present at all, are likely to be observed only after long-term administration of CF.