Doctoral Degrees (Human Nutrition)

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Browsing Doctoral Degrees (Human Nutrition) by browse.metadata.advisor "Blaauw, Renee"

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    The influence of nutrition labelling and logos on food purchasing behaviour in Cape Town, Western Cape, South Africa
    (Stellenbosch : Stellenbosch University, 2017-12) Koen, Nelene; Blaauw, Renee; Wentzel-Viljoen, Edelweiss; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Global Health. Human Nutrition.
    ENGLISH SUMMARY : Introduction: Nutrition information on food labels is a population-based approach to nutrition education that enables consumers to make healthier food choices. In South Africa (SA) there has been a paucity of data on food and nutrition labelling and the consumer since the publication of the new food-labelling legislation. Rationale: A better understanding of how consumers engage with nutrition information on food labels is required to make recommendations to improve education campaigns to assist consumers in making healthier food choices. Additionally, food-labelling factors that influence consumer food-purchasing behaviour, and expectations/barriers to reading nutrition information on labels, could assist in making recommendations for a single front-of-pack labelling scheme to be used in SA as well as for its development. Methods: A multi-stage mixed-methods design was employed. In phase one, a cross-sectional, descriptive, interviewer-administered electronic survey was conducted on adult consumers (N=960) at 16 randomly selected grocery stores in four health districts of Cape Town (CT). In phase two, nine focus-group discussions (FGDs) were held with purposively selected consumers (N=67) to further explore phase one’s findings and what type of health- endorsement logos (HELs) are preferred and why. In phase three, ten HELs were developed by a graphic design company based on the data collected in previous phases. A modified Delphi technique, conducted with experts in the fields of nutrition/food science (N=19), was employed to eliminate lowest scoring HELs and to improve the design of the HELs. Participants from the initial survey and/or FGDs took part in pilot testing of the HELs during four FGDs. Results: Main self-reported factors influencing food-purchasing behaviour included price, sell-by date and products on special/promotion, with price being the most important. Taste, brand loyalty, marketing and convenience were also major influencers. Less than half of participants indicated that nutrition information always influenced their product choice. The main reasons for not reading nutrition information included buying the same type of product all the time and being uninterested in the information. In exploring this further with FGDs, a lack of time, poor understanding of nutrition information (specifically the nutrition information table) and lack of trust in labelling information also emerged as important factors. The mean food and nutrition label knowledge score was 44%. The majority of participants preferred a single HEL to be used on food products as they don’t understand the various HELs used. Such a logo should include pictures/symbols directly related to health and/or food and should state “healthy choice”. During the pilot testing, three HELs (developed and improved during two rounds of scoring) received overall rankings of 3.08/5, 3.28/5 and 3.39/5 respectively. Conclusion: CT consumers have poor food and nutrition label knowledge and nutrition information on food labels is not a major influencer of food-purchasing behaviour. Consumers struggle to understand the nutrition information provided and have expressed a need for a single HEL to be used. Consumer education on utilising the nutrition information on labels and the development of a single HEL for SA, could assist consumers to make healthier food choices and in turn address the high incidence of non-communicable diseases in SA.
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    Nutrient intake, gastrointestinal microbiota and the effect of Lactobacillus plantarum 299V in irritable bowel syndrome patients
    (Stellenbosch : Stellenbosch University, 2014-12) Stevenson, Cheryl; Roux, Saartjie; Blaauw, Renee; Visser, Janicke; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Interdisciplinary Health Sciences:. Division of Human Nutrition.
    ENGLISH ABSTRACT: Background: Irritable bowel syndrome (IBS) is a common gastrointestinal (GI) disorder. GI symptoms and impaired quality of life affect between 10-20% of all adults, corresponding to about 25-50% of all patients who visit a gastroenterologist’s clinic. In recent years, several novel mechanisms of IBS that likely relate to previously established theories have been identified. Inflammation, postinfectious low-grade inflammation, immunological and genetic predisposition along with altered microbiota are critical in IBS development, while several dietary factors may also play a role in this syndrome. However, none of these factors accounts for the full repertoire of IBS symptoms, and the pathophysiology of this condition is not fully understood. The overarching aim of this study was to investigate the nutrient intakes, GI microbiota and the effect of Lactobacillus plantarum (L.plantarum) 299v in IBS patients. Sub-aims: 1) Update healthcare professionals on current probiotic information and provide an overview of probiotic treatment approaches, with special emphasis on IBS, 2) conduct a well designed randomised, double blind, placebo-controlled trial (RCT) with L. plantarum 299v as part of an intervention and establish whether a course of probiotics may alleviate undesirable symptoms of IBS and improve quality of life, 3) assess nutrient intake in patients with irritable bowel syndrome (IBS) compared to dietary recommendations, 4) validate and assess the reproducibility of food records and 5) identify possible nutrient risk components for establishing GI microbiota involved in IBS and as part of an intervention, determine whether a course of probiotics may alter stool microbiota. Results: 1) A review article published by the author provides an overview of current probiotic treatment options to health care professionals and indicates certain probiotics are a promising therapeutic treatment option for management of IBS symtpoms, 2) the effects of the single strain probiotic, L. plantarum 299v, supplementation was evaluated in a RCT. Compared to placebo, the probiotic supplementation showed no significant reduction in GI symptom severity scores, particularly abdominal pain relief. Quality of life was also not improved in the treatment versus control group. Both the treatment and placebo groups improved significantly over the trial period, indicating a large placebo effect, 3) nutrient intakes of the IBS patients compared to current dietary reference recommendations indicates that this group of patients are at risk for nutrient inadequacies in key macro and micronutrients, 4) the validity and reliability of the dietary data showed good reliability but poor validity as measured by plasma fatty acids and 5) the GI microbiota composition in the phenotypically different diarrhoea-predominant IBS (D-IBS) vs. constipation-predominant IBS (C-IBS) showed that D-IBS patients had significantly lower counts of Lactobacillus plantarum compared to C-IBS patients. The probiotic had no significant effects on the GI microbiota as measured by quantitative polymerase chain reaction (qPCR). It was found that nutrient intakes had a significant impact on the microbiota. Lower fibre intakes were associated with higher Bacteroides spp., lower Bifidobacteria bifidum and Lactobacillus plantarum counts in both IBS groups. Conclusion: Taken together, L.plantarum 299v did not alleviate the GI symptoms of IBS, nor was it associated with significant changes in the GI microbiota. IBS patients may be at risk of key nutrient inadequacies. The influence of nutrient intakes on the GI microbiota provides an attractive explanation as a potential pathophysiological factor for IBS.
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    Probiotics, prebiotics and synbiotics use in neonates : a critical appraisal of the evidence and evaluation of its application by the food industry
    (Stellenbosch : Stellenbosch University, 2014-04) Mugambi, Mary Letizia Nkatha; Blaauw, Renee; Young, Taryn; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Interdisciplinary Health Sciences. Human Nutrition.
    ENGLISH ABSTRACT: Background: Synbiotics, probiotics and prebiotics are being added to infant formula. This study was an in-depth evaluation of research on infants fed infant formula containing synbiotics, probiotics or prebiotics and was carried out in two phases. Phase one included two systematic reviews that assessed if synbiotics, probiotics or prebiotics led to improved growth and clinical outcomes in formula fed full term and preterm infants. Phase two included two studies: A systematic review compared the methodological quality and outcomes of industry and non-industry sponsored randomized controlled trials (RCTs) and a descriptive study evaluated how the food industry applies the knowledge and evidence gained from probiotics, prebiotics or synbiotics research in infants. The research questions were: Does the consumption of probiotics, prebiotics or synbiotics supplemented infant formula lead to improved clinical outcomes in infants? Is there an association between source of funding and methodological quality, clinical outcomes and author’s conclusions in trials using probiotics, prebiotics or synbiotics supplemented formula in infants? Does the food industry use the evidence gained through probiotics, prebiotics and synbiotics research trials on infants for the benefit of the general paediatric population? The hypotheses were: Consumption of probiotics, prebiotics or synbiotics by infants leads to improved clinical outcomes; The source of funding in research trials using probiotics, prebiotics or synbiotics supplemented formula in infants is associated with outcomes in favour of the sponsor’s products and authors’ conclusions; Methodological qualities of non-industry sponsored trials are equivalent to industry sponsored trials; Evidence gathered through probiotics, prebiotics and synbiotics research is implemented by the food industry. Methods: Phase one: Both systematic reviews on preterm and full term infants: Cochrane methodology was followed using RCTs which compared preterm or full term formula containing probiotics, prebiotics or synbiotics to conventional infant formula with / without placebo among healthy preterm or full term infants. The mean difference (MD) and corresponding 95% confidence intervals (CI) were reported for continuous outcomes, risk ratio (RR) and corresponding 95% CI for dichotomous outcomes. Phase two: In the systematic review, Cochrane methodology was used to assess the risk of bias of included RCTs. Association between source of funding and risk of bias, clinical outcomes and conclusions were assessed. In the descriptive study, all listed companies that manufacture infant food products with added synbiotics, probiotics or prebiotics for infants were identified and invited to participate. A letter of invitation was sent and if they expressed willingness to take part in the study, a questionnaire with a written consent form was sent. Descriptive statistics and associations between categorical variables were to be tested using a Chi-square test. Results: Phase one: Review on preterm infants: 8 studies were included. Probiotics increased stool frequency with no effect on other clinical outcomes. Prebiotics increased stool frequency and bifidobacteria counts only. Review on full term infants: 25 studies were included. Synbiotics improved stool frequency but had no effect on other clinical outcomes. Probiotics did not have an effect on any clinical outcome. Prebiotics increased weight gain and stool frequency with no effect on other outcomes. Phase two: Systematic review: 67 studies were included, majority were funded by food industry. There was no significant association between the source of funding and four domains (sequence generation, allocation concealment, blinding, selective reporting), majority of reported clinical outcomes or authors’ conclusions. Source of funding was significantly associated with two domains (incomplete outcome data, free of other bias), antibiotic use and conclusions on weight gain. Descriptive study: 25 companies were identified and invited to participate. No company agreed to participate in the survey for different reasons. Conclusions Phase one: Review on preterm infants: There is not enough evidence to state that supplementation with probiotics or prebiotics results in improved growth and clinical outcomes in exclusively formula fed preterm infants. Review on full term infants: There is not enough evidence to state that supplementation of term infant formula with synbiotics, probiotics or prebiotics does result in improved growth or clinical outcomes in term infants. There is no data available to establish if synbiotics are superior to probiotics or prebiotics. Phase two: Systematic review: In RCTs on infants fed infant formula containing probiotics, prebiotics or synbiotics, the source of funding does not influence majority of outcomes in favour of the sponsors’ products. More non-industry funded research is needed to further assess the impact of funding on reported clinical outcomes and authors’ conclusions. Descriptive study: Due to companies refusing to participate in this study, no conclusion could be drawn on how the food industry applies evidence gained through probiotics, prebiotics or synbiotics research on infants. More transparency is needed from the infant formula manufactures on how they apply the evidence gained from probiotic, prebiotic or synbiotic research on infants.
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    The use of probiotics in the management of necrotising enterocolitis in HIV exposed premature and very-low birth weight infants
    (Stellenbosch : Stellenbosch University, 2014-12) Van Niekerk, Evette; Kirsten, Gert; Blaauw, Renee; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Interdisciplinary Health Sciences. Division of Human Nutrition.
    ENGLISH ABSTRACT: Introduction: An association between maternal human immunodeficiency virus (HIV) infection and Necrotizing Enterocolitis (NEC) in preterm infants has been reported. The impact of probiotics in an HIV-exposed very low birth weight (VLBW) infant on the occurrence of NEC is uncertain at present; however it is known that probiotics have protective effects against inflammation and prevent NEC. Postnatal growth restriction is a major issue in preterm, especially extremely-low-birth-weight (ELBW) infants and probiotics have been found to improve feeding tolerance in preterm infants. Human milk oligosaccharides (HMO) also known as the prebiotics of human milk, are known to have bifidogenic and anti-adhesive effects. Infants that receive human milk show a reduced incidence of NEC compared to those who receive infant formula. Very little is known about the composition of breast milk in the HIV-infected mother. Objective: The primary objective of the study was to assess the effect of probiotics on the incidence and severity of NEC in high-risk infants born to HIV-positive and HIV-negative women. The secondary objectives were to assess the effect of probiotic administration on feeding tolerance and growth outcomes of HIV-exposed but uninfected preterm infants, to describe the HMO composition of HIV-infected mothers breast milk and lastly to determine if HMO composition affects the incidence of NEC in HIV-exposed preterm very low birth weight infants. Patients and Methods: A randomized, double blind, placebo controlled trial was conducted for the period July 2011 to August 2012. HIV-exposed and HIV-unexposed premature (<34 weeks gestation) infants with a birth weight of ≥500g and ≤1250g were randomized to receive either a probiotic or a placebo. The probiotic consisted of 1x109 CFU, L. rhamnosus GG and B. infantis per day and was administered for 28 days. NEC was graded according to Bell’s criteria. Anthropometrical parameters and daily intakes were monitored. Breats milk samples were analysed for oligosaccharide content. Results: 74 HIV-exposed and 110 HIV-unexposed infants were enrolled and randomized (mean birth-weight, 987g; mean gestational 28.7 weeks). The incidence of death and NEC did not differ significantly between the HIV-exposed and unexposed groups but a significantly higher NEC incidence was found in the control group. There was no difference in the average daily weight gain for treatment groups or HIV exposure. The HIV-exposed group achieved significantly higher z-scores for length and head circumference at day 28 than the unexposed group (p<0.01 and p=0.03, respectively). There were no differences in the incidence of any signs of feeding intolerance and abdominal distension between the groups. Our results show significantly higher absolute concentrations of 2’-fucosyllactose, laco-N-tetraose and lacto-N-fucopentaose 1 and higher relative abundance of 3’-sialyllactose, difucosyl-lacto-N-tetraose and fucosyl-disialyllacto-N-hexaose in HIV-infected compared to -uninfected Secretor women. DSLNT concentrations were significantly lower in the breast milk of mothers whose infants developed NEC compared to infants without NEC. Conclusion: Probiotic supplementation reduced the incidence of NEC in the premature infants; however results failed to show a lower incidence of NEC in HIV-exposed premature infants. Probiotic supplementation did not affect growth outcomes or the incidence of any signs of feeding intolerance in HIV-exposure. The data confirms previous reports that HIV-infected mothers have higher 3’sialyllactose milk concentrations. Most intriguing though, the data also indicates that low levels of DSLNT in the mother’s milk increase the infant’s risk for NEC, which is in accordance with results from previously published animal studies and warrants further investigation.