Alexa Hoyland

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 childrens 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.

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.

Short Term (14 Days) Consumption of Insoluble Wheat Bran Fibre-Containing Breakfast Cereals Improves Subjective Digestive Feelings, General Wellbeing and Bowel Function in a Dose Dependent Manner

This study investigated whether increasing insoluble (predominantly wheat bran) fibre over 14 days improves subjective digestive feelings, general wellbeing and bowel function. A single centre, multi-site, open, within subjects design with a 14 day non-intervention (baseline) monitoring period followed by a 14 day fibre consumption (intervention) period was performed. 153 low fibre consumers (<15 g/day AOAC 985.29) completed a daily symptom diary for 14 days after which they consumed one bowl of ready-to-eat breakfast cereal containing at least 5.4 g fibre (3.5 g from wheat bran) for 14 days and completed a daily symptom diary. Significant improvements were demonstrated in subjective perception of bowel function (e.g., ease of defecation) and digestive feelings (bloating, constipation, feeling sluggish and digestive discomfort). Significant improvements were also found in subjective perception of general wellbeing (feeling less fat, more mentally alert, slim, happy and energetic whilst experiencing less stress, mental and physical tiredness, difficulty concentrating and fewer headaches). In general, improvements in study outcomes increased with increasing cereal/fibre consumption. However, consuming an additional minimum 5.4 g of fibre (3.5 g wheat bran) per day was shown to deliver measurable and significant benefits for digestive health, comfort and wellbeing. Encouraging consumption of relatively small amounts of wheat bran could also provide an effective method of increasing overall fibre consumption.

Psychological benefits of weight loss: a systematic research review

Introduction: It is generally accepted that weight loss has significant physiological benefits, such as reduced risk of diabetes, lowered blood pressure and blood lipid levels. However, few behavioural and dietary interventions have investigated psychological benefit as the primary outcome. Method: Systematic review methodology was adopted to evaluate the psychological outcomes of weight loss following participation in a behavioural and/or dietary weight loss intervention in overweight/obese populations. 35 studies were selected for inclusion and were reviewed. Results: Changes in self-esteem, depressive symptoms, body image and health related quality of life (HRQoL) were evaluated and discussed.The results demonstrated consistent improvements in psychological outcomes concurrent with and sometimes without weight loss. Improvements in body image and HRQoL (especially vitality) were closely related to changes in weight. Conclusion: Although the quality of the studies reviewed was generally acceptable, only 8 out of 35 studies included a suitable control/comparison group and the content, duration of intervention and measures used to assess psychological outcomes varied considerably. Further research is required to improve the quality of studies assessing the benefits of weight loss to fully elucidate the relationship between weight loss and psychological outcomes.Introduction: The role of the workplace as an opportunity for improving health has been highlighted in recent reports. The East Midlands Platform for Health and Wellbeing is a network of private, public and voluntary sector organisations working to improve health and reduce obesity. Member organisations commit to undertake actions to improve health and wellbeing of employees, individuals and/or communities. As part of Slimming World’s commitment, this pilot assessed the merits of providing weight management support via the workplace at two large regional employers. Methods: 278 British Gas and Nottingham University Hospitals NHS Trust employees were offered 12 weeks’ support at either a bespoke workplace group or established community-based Slimming World group. Weight change was recorded weekly. Dietary and physical activity behaviours, along with aspects of psychological health were assessed by questionnaire pre and post-programme. Results: 121 employees (meeting inclusion criteria) joined a workplace-based group and 114 a community-based group. Weight and attendance: Mean joining BMI was 32.4kg/m2. 138 (59%) participants completed the programme (attended within final 4 weeks).Behaviour changes: Participants who completed both questionnaires (n=87), reported positive changes in dietary and physical activity behaviours (all p<.001) (figure 1), and psychological health (mental wellbeing, self-worth and self-esteem, all p<0.05). There were no significant differences between worksite and community intervention groups for any outcomes. Conclusion: Providing weight management support via the workplace significantly reduced weight of participants (-3.9%). Completer analysis also revealed positive changes in healthy eating habits and activity levels, and also importantly psychological health, which may impact on working life. The Slimming World programme works effectively within both the work setting and via community-based provision when employees are recruited via the workplace.

Meal Composition and Cognitive Function

There is huge commercial and public interest in the capacity for foods to influence our psychological state, wellbeing, and cognitive function. Some dietary interventions have been leapt upon by the popular press and promoted to the consumer. The evidence for some of these recommendations is at best suggestive and demands critical scientific scrutiny. Consumption of certain macronutrients is thought to lead to metabolic and biochemical changes that may influence subsequent brain function, including cognitive function and appetitive response. This review draws on studies of the acute effects of meals and their macronutrient composition and on studies which examine the effect of varying the glycemic index of foods consumed on cognitive performance. Methodological and substantive issues related to the impact of nutrition on cognitive function in a number of different populations and with regard to time of day of ingestion are discussed. Cognitive function is strongly protected in healthy normal samples and enhancement of performance is widely reported following glucose manipulations, which provide readily available neural fuel. Some nutritional manipulations which exert different metabolic effects may result in no significant effects on mood, appetite, or cognitive performance. The magnitude of metabolic and/or biochemical changes that are required to induce or detect a change in cognitive function and the potential to suppress or compensate for changes in energy and macronutrient supply as result of nutritional manipulations with different glycemic indices are discussed. Some groups, e.g., children, diabetics or those with impaired glucose tolerance, and the elderly may be more vulnerable to nutritional manipulations than young healthy adults on whom much research is based. Time of day of ingestion of foods can impact on the metabolic and cognitive effects of meals. The methodological issues and differences between studies which do and do not demonstrate effects of nutritional manipulations on mental performance are critical to understanding potential effects of meals on mental performance and the claims which can be made for particular “functional foods.” Proposed edit to text - approved in the long-term or when consumed as a part of the habitual diet which merits further research, and some of these potentially valuable nutrient interventions are considered.

Macronutrients and cognitive performance

Abstract: Macronutrients have the potential to alter cognitive function by exerting effects on neuronal cell structure, neurotransmission, energy supply to the brain and metabolism. The current chapter discusses evidence for the effects of macronutrients on cognitive performance with consideration of potential moderating factors and mechanisms of action. Portion size and macronutrient composition of meals and the time of day meals are taken are considered. The effect of glucose on cognitive performance is discussed with a focus upon the impact of Glycaemic Index, Glycaemic Load and evidence for the moderating effect of fibre on glucoregulatory function. Stress and cortisol are also considered as potential moderators of the relationship between macronutrients on cognitive performance. The implications of these findings for the food industry, nutritionists and policy-makers are discussed, and future trends and opportunities for this research area are identified.