Papers by Marjanne Senekal
South African Journal of Clinical Nutrition, Jan 29, 2012
Genotype-based personalised nutrition for obesity prevention and treatment: are we there yet? Lac... more Genotype-based personalised nutrition for obesity prevention and treatment: are we there yet? Lack of rotation across genotype groups, as it is extremely challenging, if not impossible. Steps 1 and 2 Use of appropriate statistical analyses or tests or modelling. Validation of statistical models. Consideration of multiple-test burden that may result in false positives. Control for confounders or interactions, including gene-gene interactions, age, gender, race, disease, medication use, and geographical variation. Consolidation of outcomes in meta-analytic approaches. Consideration of systems genetics for integrative studies of gene-gene lifestyle (diet)-disease-time interactions. Lack of control of confounders and validation of statistical modelling. Lack of meta-analyses on effect of genotype X lifestyle (diet) indicator on phenotype indicator, as well as confirmation of causality. Journal bias favours publication of positive results.
BMC Public Health, 2015
Background: Non-communicable Diseases (NCDs) are major health concerns in South Africa. According... more Background: Non-communicable Diseases (NCDs) are major health concerns in South Africa. According to the life cycle approach NCD prevention strategies should target children. Educators are important external factors influencing behaviour of learners. The objective of this study was to assess the prevalence of selective NCD risk factors in educators of primary school learners. Methods: A cross-sectional design was used to assess the body mass index (BMI) and waist circumference (WC), blood glucose (BG), cholesterol (BC), blood pressure (BP), perceived health and weight, and parental NCD history of 517 educators in the Western Cape of South Africa. Results: The sample included 40% males and 60% females; 64% urban and 36% rural, 87% were mixed ancestry, 11% white and 2% black. Mean age for the total group was 52 ± 10.1 years, BMI 30 ± 1.2 kg/m 2 (31% overweight, 47% obese), diastolic BP 84 ± 10.0 mmHg, systolic BP 134 ± 18.7 mmHg (46% high BP), BG 4.6 ± 2.3 mmol/L (2% high BG), BC 4.4 ± 0.9 (30.4% high BC) and WC 98 ± 14.1 cm for males (38% high WC) and 95 ± 15.3 for females (67% high WC). BMI was higher (p = 0.001) and systolic (p = 0.001) and diastolic (p = 0.005) BP lower in females. Rural educators were more obese (p = 0.001). BMI (p = 0.001) and systolic BP (p = 0.001) were lower in younger educators. Correct awareness of personal health was 65% for BP, 79.2% for BC and 53.3% for BG. Thirty-eight percent overweight/obese females and 33% males perceived their weight as normal.
PLoS ONE, 2014
Background: Some popular weight loss diets restricting carbohydrates (CHO) claim to be more effec... more Background: Some popular weight loss diets restricting carbohydrates (CHO) claim to be more effective, and have additional health benefits in preventing cardiovascular disease compared to balanced weight loss diets.
Asia Pacific journal of clinical nutrition, 2006
In the present study, we examined how well adolescents (12-13 years) are able to select the corre... more In the present study, we examined how well adolescents (12-13 years) are able to select the correct dietary aid portion sizes after having been shown different food items. We also evaluated the effectiveness of two-dimensional life-size drawings and three-dimensional food models, used as dietary aids in this process. Fifty black children and 42 white children from Johannesburg participated in the study (N = 92). Trained interviewers individually tested each child following a prescribed sequence, throughout. Each participant was shown a plate of actual food of a pre-determined weight. The participant was required to select a two-dimensional drawing, and thereafter a three-dimensional food model, which most closely resembled the real food portion. In this manner, portion size estimation was evaluated with respect to 11 different food items. Correlations between nutrients calculated from actual weight of food portions and estimates ranged from 0.842 to 0.994 (P < 0.0001), indicating...
Public Health Nutrition, 2009
The objectives of the present study were to (i) develop and validate a norm-referenced performanc... more The objectives of the present study were to (i) develop and validate a norm-referenced performance-rating scale to interpret a nutrition knowledge test developed for urban adolescents and (ii) develop a prototype for other researchers to follow when developing nutrition knowledge tests. For norm development the nutrition knowledge test (questionnaire) was administered to a sample representative of the questionnaire target group, referred to as the norm group. These included 512 adolescents in grades 8 (n 158), 10 (n 149) and 12 (n 205) at three randomly selected schools in Soweto and Johannesburg. The performance scores (in percentages) obtained by the norm group were transformed to Z-scores which were categorised into stanines using established Z-score cut-off points. For validation purposes the questionnaire was completed by 148 volunteers: sixty university dietetics students, nineteen non-nutrition university students and sixty-nine primary-school teachers. As required of an ideal norm group, the Z-scores formed a normal distribution (a bell-shaped curve). To facilitate interpretation of the results, the Z-score cut-off points for these categories were transformed back to performance scores (percentages) so that the performance of a testee could be interpreted directly from his/her performance in percentage. As is recommended, the nine stanine categories were reduced to five: very poor, fair/below average, good/average, very good/above average and excellent. The discriminatory validity of the norms was substantiated by showing that groups with known nutrition knowledge levels were rated appropriately and that the performance ratings of these groups differed significantly, with university dietetics students scoring 98.3%, primary-school teachers 20.3% and non-nutrition university students 31.6%. The norm-referenced performance-rating scale can be used with confidence to interpret the performance score achieved by a testee on the nutrition knowledge test developed for urban adolescents in South Africa. The methodology used in the study serves as a prototype for other researchers who are developing knowledge tests.
Public Health Nutrition, 2009
The aim of the present study was to develop (phase 1) and validate (phase 2) a screening question... more The aim of the present study was to develop (phase 1) and validate (phase 2) a screening questionnaire to assess the adequacy of micronutrient intake of economically active South African adults. For identification of indicator foods to be included in the screening questionnaire (phase 1), a comprehensive, eighty-six-item, quantified FFQ that reflected the food sources of thirteen selected micronutrients associated with the nutrition-related health status of South Africans was developed and completed by 554 adults of all four major ethnic groups. Resulting dietary data were subjected to stepwise regression analyses to identify indicator foods to be included in the final screening questionnaire. For validation of frequency of intake reporting of specific food items included in the screening questionnaire (phase 2), a sample of sixty-six African and eighty-four white adult volunteers of both genders completed a 7 d record as well as the screening questionnaire. The frequency of intake of specific food items derived from the two methods was then compared using Spearman correlation coefficients. Phase 1 identified thirty indicator foods that formed the basis of the screening questionnaire. In phase 2, significant correlations were found for the total group for twenty-two out of the thirty items in the questionnaire, with correlations being the best for white females and the poorest for African males and females. A screening questionnaire (thirty-item FFQ) that can be used by researchers and health professionals to assess an individual&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s risk of inadequate micronutrient intake was developed and validated.
Public Health Nutrition, 2005
Objective: The aim was to contribute to the nutritional well-being of young children living in Du... more Objective: The aim was to contribute to the nutritional well-being of young children living in Duncan Village by investigating factors that influence clinic attendance of mothers and to formulate recommendations for optimisation of accessibility of primary health care (PHC) clinics in the area. Design: PHC clinic accessibility was evaluated by assessing the experiences of mothers who attended clinics in the area as well as the experiences of health care workers (HCWs) in these clinics of service delivery and its recipients (mothers/children), using the focus group technique. The ATLAS/ti program was used to analyse the data in the following steps: preparation and importing of the data, getting to know and coding the data, retrieval and examination of codes and quotations, creation of families and creation of networks. Setting: Duncan Village, a low socio-economic urban settlement in East London, South Africa. Subjects: Focus group discussions (four to seven participants per group) were conducted with four groups of mothers who do not attend PHC clinics, six with mothers who do attend the clinics (including pregnant women) and four groups of HCWs. Results: Four networks that provide a summary of all the major trends in the data were created. The results clearly indicate that mothers in Duncan Village perceive and/or experience serious problems that make it difficult for them to attend clinic and even prevent them from doing so. These problems include both the way they are treated at the clinics (especially the problem of verbal abuse) as well as the actual services delivered (no medicines, no help, disorganised, long waiting periods, being turned away). The main problem experienced by the HCWs with service delivery seems to be a heavy workload, as well as the fact that many mothers do not come for follow-up visits. Conclusion: Efforts to increase the accessibility of PHC clinics in Duncan Village should focus on improving the relationship between mothers and HCWs and the heavy workload experienced by these workers.
Public Health Nutrition, 2006
Objective: To investigate the association between the weight status of first-year female students... more Objective: To investigate the association between the weight status of first-year female students (FYFS) and various weight management-related characteristics to identify possible components of a weight management programme for students. Design: Cross-sectional study. Setting: Female residences at a South African university. Subjects: A total of 360 FYFS. Results: Mean (^standard deviation (SD)) body mass index (BMI) of the FYFS was 21.8^2.6 kg m 22 , with 7.2% being underweight, 81.9% normal-weight, 10.0% overweight and 0.8% obese. Underweight, normal-weight and overweight students differed with regard to their perception of their weight (P , 0.001), weight goals (P , 0.001) and previous weight-loss practices (P , 0.001). Mean^SD score on the 26-item Eating Attitudes Test (EAT-26) was 8.5^9.0 with 8.4% classified as high scorers. Mean^SD score on the 34-item Body Shape Questionnaire (BSQ) was 87.7^32.2, with 76.1% classified as low, 11.9% as medium and 11.9% as high scorers. The self-concept questionnaire indicated that 36.7% had a high, 43.9% a medium and 19.4% a low self-concept. Higher BMI correlated with a higher BSQ score (P , 0.001), a lower self-concept (P ¼ 0.029) and a higher EAT-26 score (P , 0.001). Smoking was prevalent amongst 13.1% of students, and 51.2% used vitamin and/or mineral supplements. Students who quitted smoking had higher (P ¼ 0.006) BMI (22.7^2.9 kg m 22 ) than those who never smoked before (21.6^2.5 kg m 22 ). Normal-weight students were more physically active than underweight or overweight students (P ¼ 0.038). Conclusions: The specific weight management-related needs of FYFS include information about supplement use, smoking, realistic weight goals, safe and sound weight-loss methods, weight cycling, body-shape perceptions, eating attitudes and behaviours, self-concept and physical activity. Interventions aimed at correcting these problems should target all students, regardless of their BMI.
Public Health Nutrition, 2005
Objectives: To review data on the prevalence, causes and health consequences of obesity in South ... more Objectives: To review data on the prevalence, causes and health consequences of obesity in South Africa and propose interventions to prevent and treat obesity and related outcomes. Methods: Data from existing literature were reviewed with an emphasis on changing eating and activity patterns, cultural factors, perceptions and beliefs, urbanisation and globalisation. Results of studies on the health consequences of obesity in South Africans are also reviewed. Results: Shifts in dietary intakes and activity patterns to higher fat intakes and lower physical activity are contributing to a higher prevalence of obesity. Few overweight black women view themselves as overweight, and some associate thinness with HIV/AIDS. Glucose and lipid toxicity, associated with insulin resistance, play roles in the pathogenesis of the co-morbid diseases of obesity. Elevated free fatty acids in the black population predispose obese black patients to type 2 diabetes. Conclusion and recommendations: Obesity prevention and treatment should be based on education, behaviour change, political support, intersectoral collaboration and community participation, local actions, wide inclusion of the population, adequately resourced programmes, infiltration of existing initiatives, evidence-based planning, and proper monitoring and evaluation. Interventions should have the following components: reasonable weight goals, healthful eating, physical activity and behavioural change. Genes and mutations affecting susceptibility to the development of co-morbidities of obesity and vulnerable periods of life for the development of obesity should be prioritised. Prevention should be managed in community services, identification of high-risk patients in primary healthcare services and treatment of co-morbid diseases in hospital services.
Nutrition, 2005
Objectives: We wanted to develop a valid and reliable nutritional knowledge test for urban South ... more Objectives: We wanted to develop a valid and reliable nutritional knowledge test for urban South African adolescents who were participating in the Birth-to-Twenty cohort study. The questionnaire was intended for use every second year, from ages 13 to 14 y until age 20 y. Methods: The initial steps involved the development of a conceptual framework and identification of nutritional concepts in collaboration with nutritional experts, and this defined the construct of the questionnaire. The South African national teaching curriculum objectives for nutritional education and other relevant issues were selected as the desired concepts, and most items were phrased in accordance with the recently developed South African Food-Based Dietary Guidelines. Thereafter, 140 items (questions) were developed and in turn assessed by an expert panel, and the result was that only 88 items remained. This was done to ensure content and face validity of the items. The 88 items were constructed into a questionnaire and piloted for appropriateness and understanding by adolescents, ages 13 to 14 y, as a means of assessing face validity by non-experts. The edited preliminary questionnaire (still with 88 items) was administered to a nutrition expert group (n ϭ 71) versus a non-expert group (n ϭ 82), referred to as sample 1, for the purposes of performing item analysis and assessing construct validity of the questionnaire. The result of the analysis, a 63-item questionnaire, was administered to adolescents at three school grade levels, 8 (n ϭ 128), 10 (n ϭ 143), and 12 (n ϭ 98), referred to as sample 2, which was representative of the grades in which the Birth-to-Twenty group will be in when the questionnaire is administered. The questionnaire was administered to the sample to assess its content validity and internal consistency reliability. The final questionnaire had 60 items, and its construct, content, and internal consistency reliability were reassessed. Results: The final 60-item questionnaire displayed a significant difference (P Ͻ 0.0001) in the mean scores of the expert and non-expert groups tested. It had internal consistencies (Cronbach's ␣) of 0.71, 0.79, and 0.82 for grades 8, 10, and 12 respectively, and an overall value of 0.77 for all groups combined. However, it was less than 0.7 for most grade 8 pupils and for all grades at a historically disadvantaged school. Conclusion: A nutritional knowledge questionnaire with construct, face, and content validities and internal consistency was developed for use in South African adolescents to evaluate their nutritional knowledge. Internal consistency was low in children at a disadvantaged school and those in grade 8 compared with multiracial groups at a multiracial school. It is recommended that pupils at disadvantaged schools be assisted by trained interviewers when taking the test. Nutrition 21 (2005) 76 -85 www.elsevier.com/locate/nut 0899-9007/05/$ -see front matter
Nutrients, 2013
Rural areas of the Eastern Cape (EC) Province, South Africa have a high incidence of squamous cel... more Rural areas of the Eastern Cape (EC) Province, South Africa have a high incidence of squamous cell oesophageal cancer (OC) and exposure to mycotoxin fumonisin has been associated with increased OC risk. However, to assess exposure to fumonisin in Xhosas-having maize as a staple food-it is necessary to determine the amount of maize consumed per day. A maize-specific food frequency questionnaire (M-FFQ) has recently been developed. This study developed a food photograph (FP) series to improve portion size estimation of maize dishes. Two sets of photographs were developed to be used alongside the validated M-FFQ. The photographs were designed to assist quantification of intakes (portion size photographs) and to facilitate estimation of maize amounts in various combined dishes (ratio photographs) using data from 24 h recalls (n = 159), dishing-up sessions (n = 35), focus group discussions (FGD) (n = 56) and published literature. Five villages in two rural isiXhosa-speaking areas of the EC Province, known to have a high
Nutrients, 2012
Adequate vitamin D and calcium are essential for optimal adolescent skeletal development. Adolesc... more Adequate vitamin D and calcium are essential for optimal adolescent skeletal development. Adolescent vitamin D insufficiency/deficiency and poor calcium intake have been reported worldwide. Heavy alcohol use impacts negatively on skeletal health, which is concerning since heavy adolescent drinking is a rising public health problem. This study aimed to examine biochemical vitamin D status and dietary intakes of calcium and vitamin D in 12-16 year-old adolescents with alcohol use disorders (AUD), but without co-morbid substance use disorders, compared to adolescents without AUD. Substance use, serum 25-hydroxyvitamin D (s-25(OH)D) concentrations, energy, calcium and vitamin D intakes were assessed in heavy drinkers (meeting DSM-IV criteria for AUD) (n = 81) and in light/non-drinkers without AUD (non-AUD) (n = 81), matched for age, gender, language, socio-economic status and education. Lifetime alcohol dose was orders of magnitude higher in AUD adolescents compared to non-AUD adolescents. AUD adolescents had a binge drinking pattern and -weekends-only‖ style of alcohol consumption. Significantly lower (p = 0.038) s-25(OH)D (adjusted for gender, smoking, vitamin D intake) were
Journal of Applied Microbiology, 2006
Aims: Screening of five bile salt-resistant and low pH-tolerant lactic acid bacteria for inhibito... more Aims: Screening of five bile salt-resistant and low pH-tolerant lactic acid bacteria for inhibitory activity against lactic acid bacteria and bacterial strains isolated from the faeces of children with HIV/AIDS. Determining the effect of prebiotics and soy milk-base on cell viability and adhesion of cells to intestinal mucus. Methods and Results: Lactobacillus plantarum 423, Lactobacillus casei LHS, Lactobacillus salivarius 241, Lactobacillus curvatus DF 38 and Pediococcus pentosaceus 34 produced the highest level of antimicrobial activity (12 800 AU ml )1 ) when grown in MRS broth supplemented with 2% (m/v) dextrose. Growth in the presence of Raftilose Ò Synergy1, Raftilose Ò L95 and Raftiline Ò GR did not lead to increased levels of antimicrobial activity. Cells grown in the presence of Raftilose Ò Synergy1 took longer to adhere to intestinal mucus, whilst cells grown in the absence of prebiotics showed a linear rate of binding.
European Journal of Clinical Nutrition, 2002
Objective: The study's main objectives were the identification of determinants of growth failure ... more Objective: The study's main objectives were the identification of determinants of growth failure in 12 -24-month-old children from an urban slum community attending a day hospital as well as the identification of focus areas for intervention. Design: The research was executed as a case -control study with a one-to-two design. A hypothetical causal model was developed for the undernutrition situation in Duncan Village. A questionnaire to assess the direct and underlying causes of growth failure in the study population was developed from this model. Subjects: One-hundred and fifty children were selected for the study, with 100 children in the control group and 50 children in the growth-failure group. Each child in the growth-failure group was matched with two children in the control group based on age and sex. The children were chosen according to anthropometric indices and p-albumin levels. Setting: The research was conducted at a primary health care centre in Duncan Village, an overpopulated urban slum area in East London, a small city on the east coast of South Africa. Results: No significant differences were found between the two groups for the occurrence of disease and infection. Dietary intake seemed to be generally poor in all the children. No significant differences were found between the two groups for the indicators of household food security, health service utilization and environmental conditions. The most important underlying determinants of growth failure that were identified in the study population seem to be related to the caring capacity, and the resultant caring behaviours of mothers. The risk for growth failure is increased when a child has a mother who is not the head of the household (relative risk) (RR ¼ 4.3), who is not involved with the discipline of her children (RR ¼ 2.2), who is not the guardian of the child (RR ¼ 8), who was not born in Duncan Village or in a city (RR ¼ 2.16), who is not able to write (RR ¼ 2.7) or read Xhosa (RR ¼ 2.53), who has a school education of grade 9 (RR ¼ 2.9), who did not receive nutrition education (RR ¼ 2.2), who smokes (RR ¼ 10) and drinks beer regularly (RR ¼ 10), who has a BMI < 25 (RR ¼ 2.7), who was subjectively judged to show little interest in her child (RR ¼ 4) as well as an inadequate caring attitude towards her child (RR ¼ 3.61), and whose clothing was dirty (RR ¼ 2.7) and not tidy (RR ¼ 2.9). Further determinants included the following: a child who weighed < 2500 g at birth (RR ¼ 4.96), who had not received supplemental milk while still breast-fed (RR ¼ 2.00), who did not receive baby cereal as first food (RR ¼ 2.6), whose clothes (RR ¼ 2.7) were dirty and whose hands were infrequently washed (RR ¼ 10). Conclusions: The results of this research suggest that initiatives to address the problem of growth failure in 12 -24-month-old children attending the Duncan Village Day Hospital should focus mainly on improving the caring capacity of mothers in the study area.
Asia Pacific Journal of Clinical Nutrition, 2000
Lymphocyte measures in treatment-naïve 13–15-year old adolescents with alcohol use disorders
Alcohol, 2011
Many adolescents have chronic exposure to hazardous levels of alcohol. This is likely to be a sig... more Many adolescents have chronic exposure to hazardous levels of alcohol. This is likely to be a significant predictor of health outcomes, including those related to immunity. We assessed substance use and biochemical immunological parameters in heavy drinking adolescents (meeting DSM-IV criteria for alcohol dependence) and light/nondrinking control adolescents in Cape Town. Lifetime alcohol dose, measured in standard units of alcohol, was orders of magnitude higher in alcohol-dependent (AD) participants than controls. All adolescent AD had a &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;weekends-only&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; style of alcohol consumption. The AD group was chosen to represent relatively &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;pure&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; AD, with minimal other drug use and no psychiatric diagnoses. With these narrow parameters in place, we found that AD adolescents were lymphopenic compared with controls, with significantly lower mean numbers of absolute circulating CD3+, CD4+, and CD8+ T-lymphocytes. On conclusion, we found that adolescent AD individuals with excessive alcohol intake, in a weekend binge-drinking style but without comorbid drug or psychiatric disorders, may be at increased risk of lymphopenia. This alcohol misuse may increase infectious disease susceptibility (including TB and HIV) by reducing immune system capabilities. Complex interactions of alcohol with other documented high-risk activities may further compound health risks.
Ethnicity & disease, 2003
To investigate factors associated with self-reported weight status of economically active adults ... more To investigate factors associated with self-reported weight status of economically active adults from the 4 major ethnic groups in South Africa. Cross-sectional survey. South Africa. A random sample (N=2100) was selected from a database of economically active adults from the 4 major ethnic groups in South Africa (Black, White, Asian, and mixed ancestry). Of the 2100 selected, 554 subjects returned mailed questionnaires. Weight status (BMI), dieting history, meal patterns, intake of high fat food items and alcohol, level of physical activity, smoking habits, family history of obesity, and socioeconomic characteristics. Identified risk factors for overweight/obesity included: Black ethnicity, education level < or = Grade 7, inactivity, and at least one overweight parent. Protective factors included: describing one's own weight as under- or normal weight, hardly ever or never binging, not having tried to lose weight during the past year, and describing one's own health as ex...
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Papers by Marjanne Senekal