No description available.

No description available.

A series of studies of how children (aged 3-16 years) think about food and health, and the implications for nutrition education are reported. Studies 1-3 investigated the food and health concepts of 3-5 year old children (n=73) through a spontaneous food classification task and a series of structured interviews. It was found that until the age of 5 years children's thought about diet and health was dominated by phenomenism. Studies 4-6 considered the development of food and health concepts in children aged 7-16 years of age (n-222). By 7 years of age children had established a substantial diet and health knowledge base. Two periods (5-7 and 11-12 years) when children appeared potentially susceptible to nutrition education interventions were suggested. The results of the studies indicated that by 16 years of age the majority of children had well established diet and health concepts. However, a number of 16 year old participants still had difficulties classifying foods. The conclusion drawn was that although current practice in nutrition education provides children with declarative knowledge (<I>knowing that</I>), it may under-develop practical skills and procedural knowledge (<I>knowing how</I>). This suggestion was examined further through a small scale study comprising the classification strategies used by a sample of 9 year old children (n=17) before, and after, a series of food and health related interventions. The findings indicated that knowledge based teaching, that did not provide opportunities for the development of practical skills, did not result in conceptual change. The possible implications of the findings for current nutrition education were discussed, and recommendations for policy and practice made.

Much of this work involves the assessment of the effects of probiotic supplementation on the composition of antibiotic disrupted intestinal microfloras. In a double blind, placebo controlled clinical trial of patients undergoing <I>Helicobacter pylori</I> eradication therapy the effects of a probiotic comprising <I>Lactobacillus acidophilus </I>and <I>Bifidobacterium longum </I>on the faecal flora were compared. After antibiotic therapy, no change was observed among the numbers of anaerobes but the aerobic numbers increased in the antibiotic alone group; numbers of aerobes (enterobacteria) decreased in the antibiotic/probiotic group. Aerobic numbers for the probiotic re-growth population were significantly lower than the starting populations. This did not occur in the antibiotic group. In a second trial, the caecal and faecal microflora of irritable bowel syndrome (IBS) patients were compared with healthy subjects (n=8 and n=7, respectively). The composition of the caecal and faecal microfloras was comparable but numbers were lower for the caecal biopsies and caecal lumen samples. For the IBS patients, the faecal anaerobe numbers were lower than for the normal subjects and lactobacilli were not detected. The caecal samples of the IBS patients had higher numbers of aerobes than the normal subjects; lactobacilli were detected in these samples. The IBS patients were divided into two groups to receive antibiotic therapy with or without probiotic supplementation. The numbers of caecal anaerobes decreased in the antibiotic alone group but increased in the probiotic group whereas numbers of aerobes increased in both groups. Antibiotic treatment of the IBS patients favoured yeast proliferation (detected in 50% caecal samples and 75% faecal samples) but in the probiotic group, yeast growth was less abundant - only detected in 25% faecal samples.

The impact of dietary fats was assessed in Swiss mice of differing ages (juvenile and adult) and sexes for two periods (3 and 6 weeks). Mice were fed four specially-formulated pelleted diets containing respectively 8% saturated vegetable fat, 8% soya oil, 8% olive oil and 2% soya oil (with identities hidden from the experimenter) or a local commercial chow. Subjects were individually housed in traditional cages or in metabolism cages to assess daily food consumption and body weight changes over the experimental period. Traditionally-caged mice were also assessed under red lighting for behaviour in a modified 'open field' (a 30 x 20 cm box with a black floor). Videotaped records were analysed using 'The Observer' system quantifying transitions between inner and outer areas, rearing, freezing, grooming and defaecation as well as location in the two equal-sized zones. Measures were factor analysed to facilitate interpretation. Other subjects were used to assess core body temperatures as well as a range of blood (cholesterol, triglycerides and glucose) and plasma (high density lipoprotein cholesterol) measures. Animals in metabolism cages were used to determine daily production of dried faecal material and urine in response to the diets. Clearly, these non-isocaloric diets differed in palatabilities, producing complex effects on growth as well as physiological and behavioural measures. Many indices were influenced by age, sex, duration of dietary exposure and the type of caging used. Interactions between factors were common. Defaecation does not seem to provide a useful index of 'emotionality' in this type of study. Investigations lacking a wide range of indices are unlikely to provide unequivocal support for postulated links between dietary lipids and behaviour. The thesis broadly supports the contention that dietary fats subtly influence mood in mice and differentially influence blood cholesterol values and other factors relevant to coronary heart disease risk in humans.

Glucose is the primary source of energy for the brain. It seemed possible that fluctuations in the supply of glucose might influence the functioning. A series of studies considered the influence of glucose drinks, and increasing blood glucose, on self-reported mood. High blood glucose levels were associated with lower tension and greater subjective energy. A frustrating situation resulted in fewer negative behavioural responses in glucose drinkers who had fasted overnight. Mood-blood glucose relationships were examined in 12 healthy adults; relationships were idiosyncratic, however, high blood glucose tended to be related to the positive mood states of energy and calmness. Subjects whose blood glucose was rising recalled more items from a work list. Blood glucose was correlated with the number of words recalled. The glucose-induced improvement in memory occurred throughout the range of blood glucose and not just in those whose levels were low. Delayed recall of a Wechsler story was better in subjects whose blood glucose was maintained at higher levels rather than falling. Increasing blood glucose levels resulted in faster decision times and lower variability when reaction times were measured and faster responses during the incongruent test of the Stroop Task. Two different underlying mechanisms are discussed. Serotonin may be involved in the mood effects of glucose, and acetylcholine in the cognitive effects. However, as glucose is the primary fuel of the brain, it may not be possible to implicate a single transmitter.

A series of studies examined the impact of ingesting a glucose or a placebo drink on sustained attention on the Rapid Information Processing task, logical and abstract reasoning, recall of word lists, a Wechsler story, dichotic presentation of word lists, the Brown-Peterson task, the CANTAB working memory subtests and digit span. It was found the influence of glucose on cognitive performance depended on the demand and duration of the tasks, individual differences in the ability to regulate blood glucose levels and whether breakfast had been eaten. The negative effects of missing breakfast on memory could be reversed by the consumption of a glucose beverage in some situations but not others. The disassociation between the effects of breakfast and a glucose drink on cognition suggests that breakfast could modulate memory by several mechanisms, of which the increase in the provision of glucose is only one. The thesis for the first time demonstrated that individual differences in the ability to regulate blood glucose levels was related to cognitive performance in young, health adults. Good blood glucose regulation, as depicted by a fall in blood glucose levels during cognitive demand, was shown to be associated with better performance. In a dichotic listening task both a glucose drink and good blood glucose regulation was associated with a right ear advantage in word recall suggesting that glucose selectively facilitates active areas of the brain, in this case the left hemisphere. It was concluded that there is good reason to further study the possibility that the control of blood glucose levels, in the normal range, influences the cognitive functioning of young healthy adults.

No description available.

No description available.

No description available.