Functional foods: psychological and behavioural functions

Revealing the Acute Effects of Dietary Components on Mood and Cognition: The Role of Autonomic Nervous System Responses

A growing body of literature suggests dietary components can support mood and cognitive function through the impact of their bioactive or sensorial properties on neural pathways. Of interest, objective measures of the autonomic nervous system-such as those regulating bodily functions related to heartbeat and sweating-can be used to assess the acute effects of dietary components on mood and cognitive function. Technological advancements in the development of portable and wearable devices have made it possible to collect autonomic responses in real-world settings, creating an opportunity to study how the intake of dietary components impacts mood and cognitive function at an individual level, day-to-day. In this paper, we aimed to review the use of autonomic nervous system responses such as heart rate or skin galvanic response to investigate the acute effects of dietary components on mood and cognitive performance in healthy adult populations. In addition to examining the existing methodologies, we also propose new state-of-the-art techniques that use autonomic nervous system responses to detect changes in proxy patterns for the automatic detection of stress, alertness, and cognitive performance. These methodologies have potential applications for home-based nutrition interventions and personalized nutrition, enabling individuals to recognize the specific dietary components that impact their mental and cognitive health and tailor their nutrition accordingly.

Ready-to-eat cereal and milk for breakfast compared with no breakfast has a positive acute effect on cognitive function and subjective state in 11-13-year-olds: a school-based, randomised, controlled, parallel groups trial

PURPOSE

We tested the acute effect of breakfast (ready-to-eat-cereal [RTEC] and milk) versus (vs.) no breakfast on cognitive function and subjective state in adolescents.

METHODS

Healthy adolescents (n = 234) aged 11-13 years were recruited to take part in this school-based, acute, randomised, controlled, parallel groups trial with two interventions; Breakfast or No Breakfast. The breakfast intervention consisted of ad libitum intake of RTEC (up to 70 g) with milk (up to 300 ml) administered in a naturalistic school breakfast programme environment. Cognitive function was assessed at baseline and + 70 and + 215 min post-intervention in a group-testing situation, similar to a school classroom context. The CANTAB test battery included: Simple Reaction Time (SRT), 5-Choice Reaction Time (5-CRT), Rapid Visual Information Processing (RVIP), and Paired Associates Learning (PAL; primary outcome). Data collection commenced January 2011 and ended May 2011. This trial was retrospectively registered at www.clinicaltrials.gov as NCT03979027 on 07/06/2019.

RESULTS

A significant effect of the intervention (CMH[1] = 7.29, p < 0.01) was found for the number of levels achieved on the PAL task. A significant difference between interventions was found when baseline performance reached level 2 (JT, z = 2.58, p < 0.01), such that 100% of participants in the breakfast intervention reached the maximum level 4 but only 41.7% of those in the no breakfast intervention reached level 4. A significant baseline*intervention interaction (F[1,202] = 6.95, p < 0.01) was found for total errors made on the PAL task, indicating that participants who made above-average errors at baseline reduced the total number of errors made at subsequent test sessions following breakfast consumption whilst those in the no breakfast intervention did not. There was a positive effect of breakfast on reaction time and visual-sustained attention. The results also demonstrated interactions of intervention with baseline cognitive performance, such that breakfast conferred a greater advantage for performance when baseline performance was poorer.

CONCLUSION

Consuming breakfast has a positive acute effect on cognition in adolescents.

The association between eating frequency with alertness and gastrointestinal complaints in nurses during the night shift

We investigated the association of the number of eating occasions and energy intake with alertness and gastrointestinal (GI) complaints in nurses during their night shift. During this observational study we collected data on anthropometrics and demographics, eating frequency, energy intake, alertness and GI complaints in 118 healthy female nurses, aged 20 to 61 years. Nurses completed an alertness test (psychomotor vigilance task) during the night shift and a 24‐hr dietary recall and a questionnaire about GI complaints after the night shift. This was repeated three times, always on the first night shift in a night shift series. The number of eating occasions during the night shift was negatively associated with reaction times (β = −4.81 ms, 95% confidence interval [CI] −9.14 to −0.48; p = .030), and number of lapses (β = −0.04, 95% CI −0.07 to −0.00; p = .030). However, the number of eating occasions was not associated with subjective alertness and GI complaints. Energy intake during the night shift was not associated with objective or subjective alertness or with GI complaints. These associations were independent of caffeine intake, age, body mass index and dependence among the repeated measurements. The present study showed that eating frequency was positively associated with objectively measured alertness levels in female nurses during the night shift. The results need to be confirmed in an intervention study, where also timing, size and composition of the meal will be taken into account. In practice, optimising nutritional guidelines on these aspects could lead to faster responses, less (medical) errors, and a better wellbeing of night shift workers.

A meta-analytical and experimental examination of blood glucose effects on decision making under risk

Previous research has shown that short-term changes in blood glucose influence our preferences and may affect decisions about risk as well. However, consensus is lacking about whether and how blood glucose influences decision making under risk, and we conduct two experiments and a meta-analysis to examine this question in detail. In Study 1, using a pecuniary valuation method, we find no effect of blood glucose on willingness to pay for risky products that may act as allergens. In Study 2, using risky gambles, we find that low levels of blood glucose increase risk taking for food and to a lesser degree for non-food rewards. Combining our own and previous findings in a meta-analysis, we show that low levels of blood glucose on average increase risk taking about food. Low blood glucose does not increase risk taking about non-food rewards although this is subject to heterogeneity. Overall, our studies suggest that low blood glucose increases our willingness to gamble on how much food we can get, but not our willingness to eat food that can harm us. Our findings are best explained by the energy budget rule.

The Effects of a Functional Food Breakfast on Gluco-Regulation, Cognitive Performance, Mood, and Satiety in Adults

A whole diet which combines multiple functional foods benefits metabolic risk factors and cognition, but evidence supporting meal to meal benefits, which individuals may find easier to implement, is limited. This study developed a functional food breakfast (FB), using polyphenol-rich ingredients selected for their gluco-regulating and cognitive-enhancing properties, and compared it to a control breakfast (CB). For study 1, total polyphenols were determined using the Folin–Ciocalteu method, and sugar release by in vitro digestion, in frozen and fresh samples. In study 2, healthy adults (n = 16) consumed an FB, CB and ready-to-eat breakfast cereal (RTEC) in a randomised crossover design. Glucose (GR) and insulin response (IR), satiety, mood and memory were measured over 180 min. The FB was a rich source of polyphenols (230 mg) compared to the CB (147 mg) (p < 0.05), and using frozen muffins did not compromise the polyphenol content or sugar release. Peak GR was highest after the RTEC (p < 0.05), and the insulin area under the curve (AUC) was lowest in the FB at 60, 120, 180 min and peak (p < 0.05). There were no effects on GR AUC, mood, satiety or memory. Reductions in GR peak and IR following consumption of the FB support the inclusion of functional ingredients at breakfast.

Skipping Breakfast Affects the Early Steps of Cognitive Processing

Abstract. It has been generally accepted that skipping breakfast adversely affects cognition, mainly disturbing the attentional processes. However, the effects of short-term fasting upon brain functioning are still unclear. We aimed to evaluate the effect of skipping breakfast on cognitive processing by studying the electrical brain activity of young healthy individuals while performing several working memory tasks. Accordingly, the behavioral results and event-related brain potentials (ERPs) of 20 healthy university students (10 males) were obtained and compared through analysis of variances (ANOVAs), during the performance of three n-back working memory (WM) tasks in two morning sessions on both normal (after breakfast) and 12-hour fasting conditions. Significantly fewer correct responses were achieved during fasting, mainly affecting the higher WM load task. In addition, there were prolonged reaction times with increased task difficulty, regardless of breakfast intake. ERP showed a significant voltage decrement for N200 and P300 during fasting, while the amplitude of P200 notably increased. The results suggest skipping breakfast disturbs earlier cognitive processing steps, particularly attention allocation, early decoding in working memory, and stimulus evaluation, and this effect increases with task difficulty.

Weight loss, improved physical performance, cognitive function, eating behavior, and metabolic profile in a 12-week ketogenic diet in obese adults

The ketogenic diet (KD) is being increasingly promoted as a strategy to fight obesity. Although the KD is effective for weight loss and weight control, comprehensive determination of its relationship with biochemical, physiological and psychological changes is still largely unexplored. We hypothesized that a 12-week KD (12KD) would significantly affect body weight, physical performance, cognitive function, eating behaviors, the metabolic and hormonal profile in obese adults, although differently in men and women. In an uncontrolled intervention, 35 sedentary obese adults (13 men, 25 women), aged 37 ± 7 years with a BMI 36.1 ± 5.6 kg/m² underwent a 12KD between March 2017 and June 2017 at the University of Primorska. The 12KD resulted in decreased appetite, significant weight loss of participants (-18 ± 9 kg men vs. -11 ± 3 kg women; P < .001), decreased emotional and external eating (P < .001 for both), increased body image satisfaction (P < .001) and improved physical performance (P < .001). Biochemically, a significant drop in glucose (P = .026), and a significant increase in LDL-cholesterol (P = .031), CRP (P = .007), and BDNF (P = .035) were observed in the first 2 weeks; then, all listed parameters returned to baseline. On the other hand, a significant reduction in insulin (P < .001) and leptin levels (P < .001), and a significant increase in adiponectin (P = .008) and NPY (P = .009) were detected throughout the duration of the 12KD. Our results show the efficacy of the 12KD on weight loss, physical performance, cognitive function, eating behaviors and metabolic profile. However, the long-term effects of a KD on these outcomes needs to be further studied before general recommendations can be made.

The Effects of Carbohydrates, in Isolation and Combined with Caffeine, on Cognitive Performance and Mood-Current Evidence and Future Directions

This review examines the effects of carbohydrates, delivered individually and in combination with caffeine, on a range of cognitive domains and subjective mood. There is evidence for beneficial effects of glucose at a dose of 25 g on episodic memory, but exploration of dose effects has not been systematic and the effects on other cognitive domains is not known. Factors contributing to the differential sensitivity to glucose facilitation include age, task difficulty/demand, task domain, and glucoregulatory control. There is modest evidence to suggest modulating glycemic response may impact cognitive function. The evidence presented in this review identifies dose ranges of glucose and caffeine which improve cognition, but fails to find convincing consistent synergistic effects of combining caffeine and glucose. Whilst combining glucose and caffeine has been shown to facilitate cognitive performance and mood compared to placebo or glucose alone, the relative contribution of caffeine and glucose to the observed effects is difficult to ascertain, due to the paucity of studies that have appropriately compared the effects of these ingredients combined and in isolation. This review identifies a number of methodological challenges which need to be considered in the design of future hypothesis driven research in this area.

Resource forecasting: Differential effects of glucose taste and ingestion on delay discounting and self-control

We tested a novel hypothesis that glucose taste acts as a signal for resource acquisition, motivating preference for immediate rewards while actual glucose ingestion prompts resource conservation, promoting future-orientated self-regulation. In Study 1, participants were engaged in a delay-discounting task and a grip-control task before and after a beverage intervention (glucose drink, water drink, or glucose mouth-rinse). Glucose ingestion decreased delay discounting, making larger-and-later rewards more attractive. In contrast, glucose rinse increased delay discounting. Water ingestion had none of the effects. In the grip-control task, only glucose ingestion improved the performance. Study 2 using fMRI revealed that glucose rinse and glucose ingestion resulted in distinct brain activational patterns. Compared to glucose rinse, glucose ingestion deactivated a few brain regions (e.g., the anterior cingulate gyrus and inferior frontal gyrus) that are previously shown to be more active when making more difficult intertemporal choices, suggesting that glucose ingestion eases the process of making intertemporal choice. In sum, our behavioral and neuroimaging findings together suggest a dual signaling role of glucose sensation and ingestion in regulating delay discounting and self-control.

The impact of meal timing on performance, sleepiness, gastric upset, and hunger during simulated night shift

This study examined the impact of eating during simulated night shift on performance and subjective complaints. Subjects were randomized to eating at night (n=5; 23.2 ± 5.5 y) or not eating at night (n=5; 26.2 ± 6.4 y). All participants were given one sleep opportunity of 8 h (22:00 h-06:00 h) before transitioning to the night shift protocol. During the four days of simulated night shift participants were awake from 16:00 h-10:00 h with a daytime sleep of 6 h (10:00 h-16:00 h). In the simulated night shift protocol, meals were provided at ≈0700 h, 1900 h and 0130 h (eating at night); or ≈0700 h, 0930 h, 1410 h and 1900 h (not eating at night). Subjects completed sleepiness, hunger and gastric complaint scales, a Digit Symbol Substitution Task and a 10-min Psychomotor Vigilance Task. Increased sleepiness and performance impairment was evident in both conditions at 0400 h (p<0.05). Performance impairment at 0400 h was exacerbated when eating at night. Not eating at night was associated with elevated hunger and a small but significant elevation in stomach upset across the night (p<0.026). Eating at night was associated with elevated bloating on night one, which decreased across the protocol. Restricting food intake may limit performance impairments at night. Dietary recommendations to improve night-shift performance must also consider worker comfort.

Methodological Challenges in Studies Examining the Effects of Breakfast on Cognitive Performance and Appetite in Children and Adolescents

Breakfast is purported to confer a number of benefits on diet quality, health, appetite regulation, and cognitive performance. However, new evidence has challenged the long-held belief that breakfast is the most important meal of the day. This review aims to provide a comprehensive discussion of the key methodological challenges and considerations in studies assessing the effect of breakfast on cognitive performance and appetite control, along with recommendations for future research. This review focuses on the myriad challenges involved in studying children and adolescents specifically. Key methodological challenges and considerations include study design and location, sampling and sample section, choice of objective cognitive tests, choice of objective and subjective appetite measures, merits of providing a fixed breakfast compared with ad libitum, assessment and definition of habitual breakfast consumption, transparency of treatment condition, difficulty of isolating the direct effects of breakfast consumption, untangling acute and chronic effects, and influence of confounding variables. These methodological challenges have hampered a clear substantiation of the potential positive effects of breakfast on cognition and appetite control and contributed to the debate questioning the notion that breakfast is the most important meal of the day.

Effect of School-Based Home-Collaborative Lifestyle Education on Reducing Subjective Psychosomatic Symptoms in Adolescents: A Cluster Randomised Controlled Trial

In this study, we aimed to assess the effectiveness of a school-based home-collaborative lifestyle education program for adolescents (PADOK) in reducing poor subjective psychosomatic symptoms (SPS). The study was designed as a two-armed parallel cluster randomised controlled trial and the study population comprised adolescent students (aged 12–14 years, n = 1,565) who were recruited from 19 middle schools in Japan. The PADOK intervention or usual school programme was provided in schools to all eligible participants. The primary outcome was the SPS score at 6 months, while secondary outcomes included lifestyle factors, BMI, and dietary intakes. Analyses were undertaken on an intention to treat (ITT) basis accounting for the clustered design. Nineteen schools were randomised to the PADOK group (10 schools) and control group (9 schools). The numbers of students used for analysis were 1,509 for ITT and 1,420 (94.1%) for PPS. At 6 months, the crude mean change from baseline of the SPS scores by ITT analysis showed a significantly greater reduction in the PADOK group compared to that in the control group (−0.95, 95% CI −1.70 to −0.20, P = 0.016), while those for baseline-adjusted and multivariate-adjusted values showed similar directionality but were not significant (P = 0.063 and P = 0.130). The results indicated that the PADOK program may improve poor SPS scores among adolescents.

Food and Health: Expanding the Agenda for Health Psychology

In this article I consider the changing context and constitution of food in contemporary society, and the variety of ways it is bound up in health, identity and social relations. In particular, I briefly discuss the position of food in health, illness, embodiment, and the ways that food is becoming increasingly medicalized and politicized. I suggest that the treatment of food in health psychology research has frequently been overly simplistic, and argue that we need to take greater account of the complexity of food and its intricate relations to health and illness in our research if we are to investigate this topic comprehensively, and seek to contribute to better understandings and outcomes for people.

The effect of diet on the physical and mental development of children: views of parents and teachers in four European countries

Although the impact of diet on physical health is an important public health issue, less attention has been devoted to the relationship between nutrition and children's mental development. The views of parents and teachers about the extent to which diet affects physical and mental development of children were compared in four European countries. An online questionnaire (developed in English and translated) was circulated through a market research agency. Participants were parents or teachers of children aged 4-10 years without learning or behavioural issues. Questionnaires were returned by 1606 parents (401 in England, Germany and Hungary; 403 in Spain) and 403 teachers (100 in each country, except for 103 in Hungary). Teachers were older than parents (35·3 % v. 18·3 % over 45 years; P<0·001) and less likely to smoke (15·9 % v. 26·3 %, P<0·001). There was no difference between the proportions of parents and teachers who felt that a child's physical development depended very much/extremely (v. moderately/slightly/not at all) on diet (overall 79·8 %). Lower proportions of both groups thought that mental development was very much/extremely influenced by diet (67·4 %). In the regression modelling, believing that physical and mental performance was greatly influenced by diet was significantly and positively associated with living in Hungary, scoring higher on a measure of General Health Interest and (parents only) level of education attained. Differences existed among countries in most views. Lower levels of awareness of the importance of diet for brain development and cognition (compared with physical health outcomes) indicate the potential for educating consumers, especially parents with lower educational attainment.

Cognitive effects following acute wild blueberry supplementation in 7- to 10-year-old children

PURPOSE

Previously, anthocyanin-rich blueberry treatments have shown positive effects on cognition in both animals and human adults. However, little research has considered whether these benefits transfer to children. Here we describe an acute time-course and dose-response investigation considering whether these cognitive benefits extend to children.

METHODS

Using a double-blind cross-over design, on three occasions children (n = 21; 7-10 years) consumed placebo (vehicle) or blueberry drinks containing 15 or 30 g freeze-dried wild blueberry (WBB) powder. A cognitive battery including tests of verbal memory, word recognition, response interference, response inhibition and levels of processing was performed at baseline, and 1.15, 3 and 6 h following treatment.

RESULTS

Significant WBB-related improvements included final immediate recall at 1.15 h, delayed word recognition sustained over each period, and accuracy on cognitively demanding incongruent trials in the interference task at 3 h. Importantly, across all measures, cognitive performance improved, consistent with a dose-response model, with the best performance following 30 g WBB and the worst following vehicle.

CONCLUSION

Findings demonstrate WBB-related cognitive improvements in 7- to 10-year-old children. These effects would seem to be particularly sensitive to the cognitive demand of task.

Potential anti-obesogenic properties of non-digestible carbohydrates: specific focus on resistant dextrin

Alterations in the composition and metabolic activity of the gut microbiota appear to contribute to the development of obesity and associated metabolic diseases. However, the extent of this relationship remains unknown. Modulating the gut microbiota with non-digestible carbohydrates (NDC) may exert anti-obesogenic effects through various metabolic pathways including changes to appetite regulation, glucose and lipid metabolism and inflammation. The NDC vary in physicochemical structure and this may govern their physical properties and fermentation by specific gut bacterial populations. Much research in this area has focused on established prebiotics, especially fructans (i.e. inulin and fructo-oligosaccharides); however, there is increasing interest in the metabolic effects of other NDC, such as resistant dextrin. Data presented in this review provide evidence from mechanistic and intervention studies that certain fermentable NDC, including resistant dextrin, are able to modulate the gut microbiota and may alter metabolic process associated with obesity, including appetite regulation, energy and lipid metabolism and inflammation. To confirm these effects and elucidate the responsible mechanisms, further well-controlled human intervention studies are required to investigate the impact of NDC on the composition and function of the gut microbiota and at the same time determine concomitant effects on host metabolism and physiology.

Effects of hydration status on cognitive performance and mood

Although it is well known that water is essential for human homeostasis and survival, only recently have we begun to understand its role in the maintenance of brain function. Herein, we integrate emerging evidence regarding the effects of both dehydration and additional acute water consumption on cognition and mood. Current findings in the field suggest that particular cognitive abilities and mood states are positively influenced by water consumption. The impact of dehydration on cognition and mood is particularly relevant for those with poor fluid regulation, such as the elderly and children. We critically review the most recent advances in both behavioural and neuroimaging studies of dehydration and link the findings to the known effects of water on hormonal, neurochemical and vascular functions in an attempt to suggest plausible mechanisms of action. We identify some methodological weaknesses, including inconsistent measurements in cognitive assessment and the lack of objective hydration state measurements as well as gaps in knowledge concerning mediating factors that may influence water intervention effects. Finally, we discuss how future research can best elucidate the role of water in the optimal maintenance of brain health and function.

Potential benefits of satiety to the consumer: scientific considerations

Foods and dietary patterns that enhance satiety may provide benefit to consumers. The aim of the present review was to describe, consider and evaluate research on potential benefits of enhanced satiety. The proposal that enhanced satiety could only benefit consumers by a direct effect on food intake should be rejected. Instead, it is proposed that there is a variety of routes through which enhanced satiety could (indirectly) benefit dietary control or weight-management goals. The review highlights specific potential benefits of satiety, including: providing appetite control strategies for consumers generally and for those who are highly responsive to food cues; offering pleasure and satisfaction associated with low-energy/healthier versions of foods without feeling 'deprived'; reducing dysphoric mood associated with hunger especially during energy restriction; and improved compliance with healthy eating or weight-management efforts. There is convincing evidence of short-term satiety benefits, but only probable evidence for longer-term benefits to hunger management, possible evidence of benefits to mood and cognition, inadequate evidence that satiety enhancement can promote weight loss, and no evidence on which consumers would benefit most from satiety enhancement. The appetite-reducing effects of specific foods or diets will be much more subtle than those of pharmaceutical compounds in managing hunger; nevertheless, the experience of pharmacology in producing weight loss via effects on appetite suggests that there is potential benefit of satiety enhancement from foods incorporated into the diet to the consumer.

Current and previous eating practices among women recovered from anorexia nervosa: a qualitative approach

OBJECTIVE: The aim of this study was to analyze qualitatively how women, who have recovered from anorexia nervosa, perceive and describe their current eating practices, as well as the ones developed during the eating disorder period. METHODS: Seven women were interviewed individually with the objective of investigating their eating practices, transition phases and all relevant aspects that somewhat contributed to the habit-forming; experiences, feelings and perceptions related to mealtime and the influence that food has had over the present subjects' life. The interviews were analyzed by the discourse of the collective subject method. RESULTS: The results brought up the following topics: a) control; b) concerns and feelings; c) deprivation d) beauty dictatorship; e) eating competence; f) importance of food; g) food cacophony. CONCLUSIONS: What stands out is a multiplicity of eating practices, which during the eating disorder were similar to and characterized by restriction; however, after recovery, part of the subjects seem to have developed a higher eating competence, whereas others show a practice similar to the one acquired during the anorexia nervosa, such as the difficulty in realizing when they are satisfied and a feeling of discomfort when facing social interactions.

A Review of the Effects of Lunch: On Adults’ Short-term Cognitive Functioning

Because of widespread irregular lunch consumption by both children and adults, information on the effects of lunch on short-term cognitive functioning is relevant to public health. In September 2012, a MEDLINE search was conducted for studies in which the effects of lunch on cognitive performance were examined. Eleven experimental studies published from 1981 to 1996 were found and evaluated; all involved adults. In three studies, the effects of lunch and lunch skipping were compared; the remaining studies involved a determination of the effects of lunch size and lunch composition. Results of studies in which lunch was compared with no lunch indicate that lunch leads to potential impairment of some aspects of cognitive functioning in the early afternoon. Lunch size may influence cognitive functioning, with impairment more likely to occur after a large lunch than a small lunch. Furthermore, in comparison with low-fat lunches, high-fat lunches seem to result in slower but more accurate responses to some cognitive tasks. However, these suggestions must be viewed with caution, as they are based on only a few studies and are not thoroughly supported by high-quality evidence. In addition, results obtained with adults are not applicable to children. Thus, the potential effects of lunch need further examination in children and adults.

The effect of beverages varying in glycaemic load on postprandial glucose responses, appetite and cognition in 10-12-year-old school children

Reducing glycaemic index (GI) and glycaemic load (GL) inconsistently improves aspects of cognitive function and appetite in children. Whether altering the GL by lowering carbohydrate relative to protein and fat has a role in these effects is unknown. Therefore, we assessed the differential effects of beverages varying in GL and dairy composition on appetite, energy intake and cognitive function in children. A total of forty children (10–12 years) completed a double-blind, randomised, crossover trial, receiving three isoenergetic drinks (approximately 1100 kJ): a glucose beverage (GI 100, GL 65), a full milk beverage (GI 27, GL 5) and a half milk/glucose beverage (GI 84, GL 35). For 3 h post-consumption, subjective appetite and cognitive performance (speed of processing, memory, attention and perceptual speed) were measured hourly. At completion, each child was provided a buffet-style lunch and energy intake was calculated. Blood glucose was objectively measured using the Continuous Glucose Monitoring System. Blood glucose AUC values were significantly different between the drinks (P,0·001), but did not sustain above the baseline for 3 h for any drink. Mixed modelling revealed no effect of beverage on subjective appetite or energy intake. Participant sex and drink GL significantly interacted for short-term memory (P,0·001). When girls consumed either milk-containing beverage, they recalled 0·7–0·8 more words compared with 0·5 less words after the glucose drink (P#0·014). Altering GL of drinks by reducing carbohydrate and increasing protein did not affect appetite or cognition in children. Girls may demonstrate improved short-term memory after consuming beverages with higher protein and lower GL.

Appetite control and obesity

Appetite has recently received the attention of researchers in developing countries due to the increasing prevalence of obesity. There are multiple complex mechanisms involved in food intake. The satiety level and the physiological state of a person are responsible for appetite expression. Specific manipulations of macronutrients have the potential to affect appetite control. Certain pharmaceutical formulations and sensitizer compounds/chemicals can also be used as appetite suppressants either orally or intravenously. Several aspects related to appetite control and obesity have been briefly reviewed in view of the current scientific and commercial trends.

Impact of postprandial glycaemia on health and prevention of disease

Postprandial glucose, together with related hyperinsulinemia and lipidaemia, has been implicated in the development of chronic metabolic diseases like obesity, type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). In this review, available evidence is discussed on postprandial glucose in relation to body weight control, the development of oxidative stress, T2DM, and CVD and in maintaining optimal exercise and cognitive performance. There is mechanistic evidence linking postprandial glycaemia or glycaemic variability to the development of these conditions or in the impairment in cognitive and exercise performance. Nevertheless, postprandial glycaemia is interrelated with many other (risk) factors as well as to fasting glucose. In many studies, meal-related glycaemic response is not sufficiently characterized, or the methodology with respect to the description of food or meal composition, or the duration of the measurement of postprandial glycaemia is limited. It is evident that more randomized controlled dietary intervention trials using effective low vs. high glucose response diets are necessary in order to draw more definite conclusions on the role of postprandial glycaemia in relation to health and disease. Also of importance is the evaluation of the potential role of the time course of postprandial glycaemia.

Meal timing and composition influence ghrelin levels, appetite scores and weight loss maintenance in overweight and obese adults

BACKGROUND

Although dietary restriction often results in initial weight loss, the majority of obese dieters fail to maintain their reduced weight. Diet-induced weight loss results in compensatory increase of hunger, craving and decreased ghrelin suppression that encourage weight regain. A high protein and carbohydrate breakfast may overcome these compensatory changes and prevent obesity relapse.

METHODS

In this study 193 obese (BMI 32.2±1.0kg/m(2)), sedentary non diabetic adult men and women (47±7years) were randomized to a low carbohydrate breakfast (LCb) or an isocaloric diet with high carbohydrate and protein breakfast (HCPb). Anthropometric measures were assessed every 4weeks. Fasting glucose, insulin, ghrelin, lipids, craving scores and breakfast meal challenge assessing hunger, satiety, insulin and ghrelin responses, were performed at baseline, after a Diet Intervention Period (Week 16) and after a Follow-up Period (Week 32).

RESULTS

At Week 16, groups exhibited similar weight loss: 15.1±1.9kg in LCb group vs. 13.5±2.3kg in HCPb group, p=0.11. From Week 16 to Week 32, LCb group regained 11.6±2.6kg, while the HCPb group lost additional 6.9±1.7kg. Ghrelin levels were reduced after breakfast by 45.2% and 29.5% following the HCPb and LCb, respectively. Satiety was significantly improved and hunger and craving scores significantly reduced in the HCPb group vs. the LCb group.

CONCLUSION

A high carbohydrate and protein breakfast may prevent weight regain by reducing diet-induced compensatory changes in hunger, cravings and ghrelin suppression. To achieve long-term weight loss, meal timing and macronutrient composition must counteract these compensatory mechanisms which encourage weight regain after weight loss.

Refined carbohydrate intake in relation to non-verbal intelligence among Tehrani schoolchildren

Objective

Nutrition has long been considered one of the most important environmental factors affecting human intelligence. Although carbohydrates are the most widely studied nutrient for their possible effects on cognition, limited data are available linking usual refined carbohydrate intake and intelligence. The present study was conducted to examine the relationship between long-term refined carbohydrate intake and non-verbal intelligence among schoolchildren.

Design

Cross-sectional study.

Setting

Tehran, Iran.

Subjects

In this cross-sectional study, 245 students aged 6–7 years were selected from 129 elementary schools in two western regions of Tehran. Anthropometric measurements were carried out. Non-verbal intelligence and refined carbohydrate consumption were determined using Raven's Standard Progressive Matrices test and a modified sixty-seven-item FFQ, respectively. Data about potential confounding variables were collected. Linear regression analysis was applied to examine the relationship between non-verbal intelligence scores and refined carbohydrate consumption.

Results

Individuals in top tertile of refined carbohydrate intake had lower mean non-verbal intelligence scores in the crude model (P < 0·038). This association remained significant after controlling for age, gender, birth date, birth order and breast-feeding pattern (P = 0·045). However, further adjustments for mother's age, mother's education, father's education, parental occupation and BMI made the association statistically non-significant. We found a significant inverse association between refined carbohydrate consumption and non-verbal intelligence scores in regression models (β = −11·359, P < 0·001). This relationship remained significant in multivariate analysis after controlling for potential confounders (β = −8·495, P = 0·038).

Conclusions

The study provides evidence indicating an inverse relationship between refined carbohydrate consumption and non-verbal intelligence among Tehrani children aged 6–7 years. Prospective studies are needed to confirm our findings.

The effect of high lactose-isomaltulose on cognitive performance of young children. A double blind cross-over design study

Changes in blood glucose are hypothesized to influence cognitive performance and these changes can be affected by certain nutrients. This double-blind 4-period cross-over study evaluated the effects of a slow-release modified sucrose (isomaltulose) in combination with a high concentration of lactose on cognitive performance of 5-6 year old children. Thirty children received a standard growing upmilk (Std GUM), reformulated growing up milk (Reform GUM), standard growing up milk with lactose-isomaltulose (Iso GUM), and a standard glucose drink (Glucose). The CDR System, a computerised cognitive assessment system, was used to assess various measures of attention and memory of the children at baseline (T=0), 60 (T=1), 120 (T=2), and 180 (T=3) minutes following the intake of test products. Overall, there was a decline in performance over the morning on almost every cognitive task. Children showed better attention following consumption of Iso GUM compared to Std GUM but attention was not significantly different than Reform GUM and glucose. Also, Iso GUM conferred a beneficial effect over both Reform GUM and glucose on sensitivity index of numeric working memory with no difference observed between Iso GUM and Std GUM. Surprisingly, glucose group showed lowest decline in the sensitivity index of spatial working memory and highest speed in picture recognition, although the latter was significantly better than Reform GUM only. For speed of spatial working memory, Reform GUM had the lowest decline but was significantly different only with Std GUM. There was, however, no significant difference among conditions for continuity of attention, speed of numeric working memory and picture recognition sensitivity. Despite the small sample size, the findings are intriguing as carbohydrate composition seems to influence some aspects of cognitive performance such as attention and memory. However, further studies are needed to confirm these findings.

Manipulation of glycemic response with isomaltulose in a milk-based drink does not affect cognitive performance in healthy adults

Previous research suggests that glucoregulation and nutrient interventions, which alter circulating glucose, impact cognitive function. To examine the effect of modulating glycemic response using isomaltulose on cognitive function 24 healthy male adult participants consumed energy and macronutrient-matched milk-based drinks containing 50 g isomaltulose, 50 g sucrose or a water control in a counterbalanced within-subject design. Interstitial glucose was measured continuously in 12 subjects and all provided 9 capillary measures on each test day. A 30-min cognitive test battery was administered before and twice (+35 and +115 min) after drink ingestion. Immediate, delayed, recognition, verbal and working memory, and psychomotor performance were assessed. Glycemic profiles induced by the drinks differed significantly during the first but not the second post-drink test battery. Neither administration of the sucrose nor isomaltulose drinks produced consistent effects on verbal or working memory, or psychomotor performance. This study used isomaltulose as an investigative tool to lower glycemic response. Importantly, it demonstrates a lack of effect of modulating glucose on cognitive performance based on reliable, continuously measured glycemia. It refutes the hypothesis that glycemia is associated with cognitive performance and questions the suggestion that isomaltulose has an effect on cognitive performance.

A systematic review of the effect of breakfast on the cognitive performance of children and adolescents

Breakfast is recommended as part of a healthy diet because it is associated with healthier macro- and micronutrient intakes, BMI and lifestyle. Breakfast is also widely promoted to improve cognitive function and academic performance, leading to the provision of breakfast initiatives by public health bodies. Despite this positive and intuitive perception of cognitive benefits, there has been no systematic review of the evidence. Systematic review methodology was employed to evaluate the effects of breakfast on cognitive performance in well-nourished children and nutritionally at-risk or stunted children. Acute experimental studies, school feeding programmes and studies of habitual breakfast intake are reviewed. Comparisons of breakfast v. no breakfast and breakfasts differing in energy and macronutrient composition are discussed. Included are forty-five studies described in forty-one papers published between 1950 and 2008. The evidence indicates that breakfast consumption is more beneficial than skipping breakfast, but this effect is more apparent in children whose nutritional status is compromised. There is a lack of research comparing breakfast type, precluding recommendations for the size and composition of an optimal breakfast for children's cognitive function. Few studies examined adolescents. Studies of school breakfast programmes suggest that such interventions can have positive effects on academic performance, but this may be in part explained by the increased school attendance that programmes encourage. The present systematic review considers methodological issues in this field and makes recommendations for future research design and policy priorities.

The influence of carbohydrate on cognitive performance: a critical evaluation from the perspective of glycaemic load

Links between nutrition and cognition are widely acknowledged. Within the context of short-term cognitive performance, carbohydrate has been the dietary component most commonly investigated. The majority of studies investigating the influence of carbohydrate on cognitive performance have employed oral glucose drink interventions followed by measures of performance on cognitive tests. More recently, studies have investigated the effect of different carbohydrates on cognitive performance rather than just pure glucose drinks. To date, studies have not been evaluated based on a standardised measure of glycaemic response, such as glycaemic load. The present review provides a critical evaluation of eight studies that have explored the relationships between food carbohydrate and cognitive performance and allow glycaemic load to be used as a basis for comparison. The key finding is that these provide insufficient evidence to support a consistent effect of glycaemic load on short-term cognitive performance. Future studies should employ consistent test methodologies and describe food interventions in more detail to facilitate meaningful comparisons and interpretations of results.

Influence of having breakfast on cognitive performance and mood in 13- to 20-year-old high school students: results of a crossover trial

OBJECTIVE

The goal was to determine whether breakfast had effects on the cognitive performance and mood of high school students.

METHODS

A crossover trial was performed in boarding schools, involving 104 students between 13 and 20 years of age. The participants were randomly assigned to 2 equal-size groups on the morning of the first testing day. One half of the total sample received a standardized breakfast, whereas the other half received no breakfast. Seven days later, the treatment order was reversed. Measurements of cognitive function included standardized tests of attention and concentration, as well as tests of verbal and spatial memory. In addition, mood was rated with a self-administered questionnaire covering the dimensions of positive and negative affect, information uptake, arousal, and alertness. Statistical analysis consisted of repeated-measures analysis of variance.

RESULTS

Breakfast had no effect on sustained attention among high school students. Visuospatial memory was improved in male students. Self-reported alertness improved significantly in the entire study population. Male students reported feeling more positive after consuming breakfast, compared with the fasting condition.

CONCLUSIONS

This crossover trial demonstrated positive short-term effects of breakfast on cognitive functioning and self-reported alertness in high school students.

Acute effects of macronutrient manipulations on cognitive test performance in healthy young adults: A systematic research review

The potential for foods to exert effects on behaviour is increasingly recognised. Previous studies have incorporated both well-known and lesser-known cognitive tests in the evaluation of relationships between macronutrient interventions and mental performance. Systematic review methodology was used to identify studies of macronutrient effects on cognition, limited to acute effects in young, fasted, healthy adults. Thirty-one studies met the inclusion criteria, yielding a total of 134 outcome measures. The studies reviewed displayed a predominance of soluble glucose manipulations, and a paucity of complex carbohydrate, protein or fat manipulations. Memory performance was most commonly measured, but verbal fluency, attention, reaction time, psychomotor skill and problem solving were also assessed. Significant differences in performance tended to occur under circumstances of more intense cognitive demand and after delays. Memory emerged as the most sensitive cognitive modality to macronutrient manipulations. Tasks identified as sensitive included Serial Sevens, Free Word Recall and Cued Word Recall, with tentative support for the Word Recognition Task. Findings also suggested that visuo-spatial memory may be influenced by macronutrient manipulations.

Is coffee a functional food?

Definitions of functional food vary but are essentially based on foods' ability to enhance the quality of life, or physical and mental performance, of regular consumers. The worldwide use of coffee for social engagement, leisure, enhancement of work performance and well-being is widely recognised. Depending on the quantities consumed, it can affect the intake of some minerals (K, Mg, Mn, Cr), niacin and antioxidant substances. Epidemiological and experimental studies have shown positive effects of regular coffee-drinking on various aspects of health, such as psychoactive responses (alertness, mood change), neurological (infant hyperactivity, Alzheimer's and Parkinson's diseases) and metabolic disorders (diabetes, gallstones, liver cirrhosis), and gonad and liver function. Despite this, most reviews do not mention coffee as fulfilling the criteria for a functional food. Unlike other functional foods that act on a defined population with a special effect, the wide use of coffee-drinking impacts a broad demographic (from children to the elderly), with a wide spectrum of health benefits. The present paper discusses coffee-drinking and health benefits that support the concept of coffee as a functional food.

Cognitive performance is associated with macronutrient intake in healthy young and middle-aged adults

PRIMARY OBJECTIVE

The objective was to examine whether dietary intakes of macronutrients are associated with neuropsychological performance.

RESEARCH DESIGN AND METHOD

Study participants were 3960 adults aged 20-59 years, who completed three neuropsychological tests and a 24-hour dietary recall as a part of the Third National Health and Nutrition Examination Survey, 1988-1994. Poor performance was defined as the test score below gender-specific 15th percentile.

MAIN OUTCOMES AND RESULTS

While holding the energy percentages from different macronutrients, additional 100 kcal intake of energy was associated with a reduced odds of poor performance on serial digital learning test (OR = 0.98, 95% CI = 0.96, 0.99) and symbol digital substitution test (OR = 0.97, 95% CI = 0.96, 0.99). Compared with equivalent energy from carbohydrates, each 5% of energy from poly-unsaturated fatty acids (PUFA) or total fat was associated with a reduced OR of poor performance on simple reaction time test (PUFA: OR = 0.77, 95% CI = 0.63-0.95 and total fat: OR = 0.93, 95% CI = 0.87, 0.99). Poor global cognition was associated with an additional intake of 100 mg cholesterol (OR = 1.14, 95% CI = 1.05, 1.23). These associations were more salient in men.

CONCLUSION

Habitual intake of macronutrients is weakly but significantly associated with cognitive functioning. These relationships are more evident in men.

Job strain, worksite support, and nutrient intake among employed Japanese men and women

BACKGROUND

The association of job strain (as defined by the job demands/control model) and worksite support with nutrient intake is not clear.

METHODS

A questionnaire survey was conducted of 25,104 workers employed in nine companies in Japan. Job strain and worksite support were assessed using the Job Content Questionnaire. Daily intake of 17 nutrients was measured using a dietary history questionnaire. Data from 15,295 men and 2,853 women were analyzed, controlling for age, education, marital status, occupation, and study site.

RESULTS

Among men, job strain was positively associated with average daily intakes of fat, vitamin E, cholesterol, poly- and mono-unsaturated fatty acids (p for trend<0.05), and worksite support was positively associated with average daily intakes of total energy, crude fiber, retinol, carotene, vitamins A, C, and E, cholesterol, and saturated fatty acid (p for trend<0.05). Among women, worksite support was positively associated with average daily intakes of total energy, protein, vitamin E, and polyunsaturated fatty acid (p for trend<0.05). However these differences were generally small.

CONCLUSIONS

The present study showed that job strain and worksite support were only weakly and inconsistently associated with nutritional intakes. It does not seem that changes in nutritional intakes explain the association between job strain or worksite support and coronary heart disease.

General methodological considerations for the assessment of nutritional influences on human cognitive functions

The premise that cognitive functioning can be influenced through dietary means has gained widespread interest. The assessment of cognitive functioning is a key method to scientifically substantiate such nutritional effects on cognition. The current paper provides a basic overview of the main concepts, issues and pitfalls of human cognitive research. General methods of cognitive assessment, selection of appropriate tests, factors that may mediate task performance and issues pertaining to the interpretation of the results are discussed.

Effect of breakfast composition on cognitive processes in elementary school children

The relationship between breakfast composition and cognitive performance was examined in elementary school children. Two experiments compared the effects of two common U.S. breakfast foods and no breakfast on children's cognition. Using a within-participant design, once a week for 3 weeks, children consumed one of two breakfasts or no breakfast and then completed a battery of cognitive tests. The two breakfasts were instant oatmeal and ready-to-eat cereal, which were similar in energy, but differed in macronutrient composition, processing characteristics, effects on digestion and metabolism, and glycemic score. Results with 9 to 11 year-olds replicated previous findings showing that breakfast intake enhances cognitive performance, particularly on tasks requiring processing of a complex visual display. The results extend previous findings by showing differential effects of breakfast type. Boys and girls showed enhanced spatial memory and girls showed improved short-term memory after consuming oatmeal. Results with 6 to 8 year-olds also showed effects of breakfast type. Younger children had better spatial memory and better auditory attention and girls exhibited better short-term memory after consuming oatmeal. Due to compositional differences in protein and fiber content, glycemic scores, and rate of digestion, oatmeal may provide a slower and more sustained energy source and consequently result in cognitive enhancement compared to low-fiber high glycemic ready-to-eat cereal. These results have important practical implications, suggesting the importance of what children consume for breakfast before school.