Masters Degrees (Faculty of Science (former Departments))

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Browsing Masters Degrees (Faculty of Science (former Departments)) by Subject "Dissertations -- Dietetics"

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    The development of a valid and reliable nutrition knowledge questionnaire and performance-rating scale for urban South African adolescents participating in the 'Birth-to-Twenty' study
    (Stellenbosch : University of Stellenbosch, 2005-04) Whati, Lindiwe Harriet; Senekal, M.; Steyn, N. P.; Lombard, C. J.; Nel, J. H.; University of Stellenbosch. Faculty of Science. Dept. of Consumer Science.
    ENGLISH ABSTRACT: The Birth to Twenty (BTT) study involves the monitoring of the health status and related factors of urban-born children from birth until age twenty. When the cohort reached age 13 years in 2003, nutrition knowledge assessment was identified as an important new priority and a nutrition knowledge questionnaire was required for these purposes. Subsequently a valid and reliable nutrition knowledge questionnaire was developed for the BTT study. This process started with the development of a conceptual framework of nutrition-related issues facing urban South African adolescents and identification of related nutrition concepts. A pool of potential questionnaire items reflecting the concepts was subsequently developed. These items were evaluated by an expert panel to ensure content and face validity before being structured into a questionnaire. The resulting 88-item questionnaire was completed by adult and adolescent samples, each age group comprising subgroups of those likely to have good nutrition knowledge and those likely to have poor nutrition knowledge. The data obtained from the completion of the questionnaire by these groups was used to refine the questionnaire through the determination of difficulty and discriminatory indices of the items, and the deletion of items that did not meet the stated criteria. The construct validity of the remaining 63 items was assessed using the same data set. To assess the internal consistency reliability (ICR) of the 63-item questionnaire it was completed by an adolescent sample population considered to be representative of the BTT cohort, after which the questionnaire underwent further steps of refinement. The result was a 60-item questionnaire of which the ICR and construct validity was reassessed and found to be satisfactory. However, to ensure the accurate interpretation of scores obtained by testees, the development of a performance-rating scale was necessary. A norm-referenced performance-rating scale (norms) was developed by administering the nutrition knowledge questionnaire to a sample population similar to the BTT cohort (norm group) and transforming their performance scores to z-scores. The z-scores ranges were then categorised into stanines, thereby resulting in a norm-referenced performance-rating scale that can be used to rate the performance of the BTT cohort. The validity of the norms was assessed by administering the nutrition knowledge questionnaire to three validation groups that comprised groups who were expected to obtain different performance-ratings on the questionnaire based on their varying levels of nutrition knowledge. The validation groups performed as expected, with significant differences in performance-rating profiles found among the three groups, indicating the validity of the norms. The study was successful in developing a reliable and valid nutrition knowledge questionnaire for use on the urban adolescents who participate in the BTT study. A norm-referenced performance-rating scale for use with the questionnaire was also successfully developed. The questionnaire and norms will be useful in assessing nutrition knowledge as well as in comparing the changes in knowledge of the BTT cohort as they move from lower to higher school grades.
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    Impact of a multidimensional weight-management programme on the weight status and associated factors of first-year female students
    (Stellenbosch : Stellenbosch University, 2004-03) Cilliers, Janetta; Senekal, M.; Kunneke, E.; Stellenbosch University. Faculty of Science.
    ENGLISH ABSTRACT: First-year female students (FYFS), studying at the University of Stellenbosch were previously identified as a high-risk group for gaining weight. A four-year follow-up of these female students indicated that a large percentage experience weight fluctuations throughout their university careers. The unique weight management needs of the FYFS were also identified in the longitudinal study. The integration of these results with an extensive search and assessment of the weight management literature led to the development of a multidimensional weight-management paradigm for application in the development of weight-management interventions for female students. Subsequently, a self-help weight-management manual, which follows the multidimensional approach proposed in the mentioned paradigm, was developed to address the unique weight-management needs of female students. The aim of the current study was to evaluate the impact of the multidimensional self-help weightmanagement manual (the Manual) on the weight status and associated factors of FYFS at the University of Stellenbosch over an eight-month period. For this purpose a non-randomized quasi-experimental design was used, including purposively selected experimental and control groups. Data were obtained during February (Baseline), May (three months after baseline = Follow-up I) and October 2002 (eight months after baseline = Follow-up 2). All students in the experimental group received the Manual at Baseline for use during the eight-month study period. Because this was a low-intensity intervention programme, no further contact was made with either group during the study period, except when Followup I data were obtained. Measures that were taken and instruments that were completed include the following: weight, height, triceps skinfoid, mid-upper ann circumference, hip circumference, waist circumference, Adolescent Self-Concept Scale (self-concept), Body Shape Questionnaire (body shape concerns), Eating Attitudes Test (eating attitudes and behaviours), General Health Questionnaire (general psychological well-being), 90-item Semi-quantified Food Frequency Questionnaire (dietary intake from nine food groups), and the Baecke Questionnaire of Habitual Physical Activity (physical activity). Additional questions on weight related perceptions and practices, dissatisfaction with body parts, reasons for eating and socio-demographic factors were also included. The Baseline characteristics of the FYFS involved in this study, which did not differ between the experimental and control groups for all key variables, identified them as a typical group of young female adults who are healthy but are not realistic about their weight status and who experience numerous problems related to their weight status. The implementation of the Manual was found to be significantly effective in limiting weight gain among the FYFS in the experimental group. The control group experienced almost a full unit increase in BMI (0.93 kg/m²), while the increase found for experimental group was 0.53 kg/m² (p=0.004). Although the weight of both groups increased initially the experimental group went on to lose weight, while the control group continued to gain weight during the last five months of the intervention. The impact of the Manual is further illustrated by the fact that the FYFS in the experimental group who indicated that they did Lise the Manual extensively experienced a significantly lower rise in their weight (change in BMI over study period = 0.37 kg/m²) than those in the experimental group who indicated that they did not use the Manual (change in BMI over study period = 0.89 kg/m²). Factors that are possibly linked to the success attained with the Manual were identified and include more reasonable weight goals; the use of sound weightreduction methods such as a balanced diet and physical activity; improvements in self-concept; maintenance of physical activity levels, especially during the first three months at university; improvement in general psychological well-being; decreased intake of foods from the "other" (includes mainly high fat, sugar based foods such as doughnuts, cookies, cake, tart), beverage and grains food groups; and possibly less concerns with body shape from the start. Factors for which no link with weight management success could be established include changes in body composition; perceptions of own weight; weight loss attempts; foods from the vegetables, fruit, milk and cheese, meat, fish and chicken, fats and fast foods food groups; physical activity over the total eight-month period; reasons for eating; eating attitudes and behaviour; dissatisfaction with body parts; and body shape concerns. It is recommended that the implementation of the Manual on the campus of the University of Stellenbosch to prevent weight gain of FYFS should be considered, bearing in mind some of the recommendations formulated by the FYFS in the experimental group.
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    Market and product assessment of probiotics and prebiotics and probiotic strains for commercial use
    (Stellenbosch : Stellenbosch University, 2004-03) Brink, Marelize; Senekal, M.; Dicks, Leon Milner Theodore; Stellenbosch University. Faculty of Science.
    ENGLISH ABSTRACT: Probiotics (live microbes) and prebiotics (non-digestible food-ingredients) are rapidly gaining interest worldwide as supplements and functional food ingredients but little South African information in this regard is available. Furthermore, the availability of South African produced probiotic concentrates for commercial use is also very limited. The aims of this study therefore were to complete a market and product assessment of probiotic and prebiotic containing products in South Africa and to evaluate probiotic strains for commercial use in South Africa. For the purposes of market and product assessment probiotic and/or prebiotic containing products manufactured in South Africa were identified. The scientific and legal correctness of health and content claims made on the labels of the products were assessed. An exploratory survey was conducted to determine the awareness of South African consumers of probiotics and prebiotics. For the evaluation of probiotic strains for potential commercial use in South Africa, a panel of twelve lactic acid bacteria (LAB) were screened for inhibitory activity against two porcine pathogens and indicator strains from the LMG-panel isolated from the faeces of patients diagnosed with AIDS. The five LAB with the best inhibitory activity were tested for growth in soymilk-base and for the effect of lyophilization on the inhibitory activity thereof. The effect of prebiotics on the growth and inhibitory activity of the strains was tested in vitro. A range of products containing probiotics and prebiotics available on the South African market was identified. Irregulatories concerning health claims on the labels were found, but content claims seemed to be less of a problem. The results also indicate that the proposed South African regulations for the labelling of probiotic and prebiotic containing products need to be revised to include the probiotic and prebiotic related health claims for which sufficient scientific evidence is available. The probiotic strains with potential for commercial use in South Africa that were identified, include Lactobacillus plantarum 423, Lactobacillus casei LHS, Lactobacillus salivarius 241, Lactobacillus curvatus DF38 and Pediococcus pentosaceus 34. These strains were grown successfully in soymilkbase and lyophilization did not have a negative effective on the inhibitory activity thereof. The growth and inhibitory activity of the five LAB were promoted when combined with 1% (w/v) Raftilose® Synergyl . It is concluded that although a variety of probiotic and prebiotic containing products are available on the South African market, the scientific and legislative correctness of especially health related claims is not satisfactory and that South African consumer awareness of these products is low. It is also concluded that a combination of at least three of the five identified LAB and 1% Raftilose® Synergy can be used by South African manufacturers for the production of probiotic and prebiotic containing supplements.