1,720,982 research outputs found
Evidence-based nutrition - review of epidemiological studies
No full textResults from epidemiological studies are often used to explore the relationships between nutrition and health. The objective of this paper is to provide guidelines for evaluating the quality and strength of evidence from different types of epidemiological studies (including ecological, cross-sectional, case-control, cohort and experimental studies) for conclusions about the relationship between nutrition and health.The discussion include advantages and disadvantages of these different types of studies, exposures, outcomes, the role of chance, bias and confounding factors, recruitment and sampling procedures and criteria, study size and power, measurement error (random and systematic), time effects, observer and participant effects, compliance, as well as analysis and interpretation of results. A checklist for reviewing epidemiological studies is given as guide to assess the quality of the data and the suitability of the study results for specific conclusions
Evidence-based nutrition
No full textThe evidence-based approach has recently been implemented to translate the vast body of literature available into effective action aimed at addressing the pressing nutritional problems that affect populations.In this paper, the first in a series on the topic, the meaning of evidence-based nutrition (EBN) is clarified and the broad outlines of how to review and interpret both individual papers and reviews of a collection of papers is discussed.The objectives of the EBN approach and the steps to follow in the process are outlined. A useful checklist for the critical appraisal of research papers is given and criteria for reviewing reviews of all relevant available information are discussed. The benefits of the EBN approach are highlighted
Integrated nutrition science: from theory to practice in South Africa
No full textObjective: To describe an integrated, holistic conceptual framework and research paradigm for a better understanding of the nutrition transition in middle- and low-income countries.Motivation: Current inability effectively to prevent the increasing burden related to changes in food consumption patterns and other health behaviours of populations in transition motivates a new approach for nutrition research and practice. In this proposed approach, broader and integrated dimensions of science and practice may be applied for a better understanding of this complex phenomenon.Result: Examples from our own studies are given and quoted to illustrate how results from transdisciplinary studies were used to design an integrated, holistic programme to improve quality of life of people infected with HIV.Conclusion: Based on these experiences it is argued that the more holistic and integrated approach should and could lead to more effective and sustainable interventions to prevent the adverse health consequences of the nutrition transition. At the same time such an approach will contribute to efforts to conserve the environment and also human, living and natural resources
Cardiovascular disease risk factors and socio-economic position of Africans in transition: the THUSA study
No full textIn many developing countries with advanced stages of the nutrition transition, the burden of coronary artery disease (CAD) has shifted from the rich to the poor. In South Africa, it is mainly the African population that is experiencing rapid urbanisation and the nutrition transition. It is not clear where the burden of CAD lies in this population group. We tried to answer this question by comparing CAD risk factors within African groups of different socio-economic positions (characterised by total household income and education level) that participated in the THUSA study from 1996 to 1998. The THUSA study was a cross-sectional population- based epidemiological study that examined the influence of urbanisation and related changes in lifestyle and eating patterns on health and disease risk. A total of 1 854 apparently healthy African volunteers were recruited from 37 randomly chosen sites in rural and urban areas of the North-West Province. The results indicated that although the group with the highest socio-economic position had significantly lower serum glucose levels, systolic blood pressures, higher micronutrient intakes and fewer smokers, their sustained increases in total and saturated fat intakes and higher serum total and LDL cholesterol levels, as well as increased body mass indices in men suggested that at that point in time and possibly in the foreseeable future, the burden of CAD will be carried by those Africans with higher socio-economic position
Meta-analysis of the health effects of using the glycaemic index in meal-planning
No full textDiabetes mellitus and CVD are some of the leading causes of mortality and morbidity. Accumulating data indicate that a diet characterised by low-glycaemic index (GI) foods may improve the management of diabetes or lipid profiles. The objective of the present meta-analysis was to critically analyse the scientific evidence that low-GI diets have beneficial effects on carbohydrate and lipid metabolism compared with high-GI diets. We searched for randomised controlled trials with a crossover or parallel design published in English between 1981 and 2003, investigating the effect of low-GI v. high-GI diets on markers for carbohydrate and lipid metabolism. Unstandardised differences in mean values were examined using the random effects model. The main outcomes were fructosamine, glycated Hb (HbA1c), HDL-cholesterol, LDL-cholesterol, total cholesterol and triacylglycerol. Literature searches identified sixteen studies that met the strict inclusion criteria. Low-GI diets significantly reduced fructosamine by -0·1 (95 % CI -0·20, 0·00) mmol/l (P=0·05), HbA1c by 0·27 (95 % CI -0·5, -0·03) % (P=0·03), total cholesterol by -0·33 (95 % CI -0·47, -0·18) mmol/l (P<0·0001) and tended to reduce LDL-cholesterol in type 2 diabetic subjects by -0·15 (95 % CI -0·31, -0·00) mmol/l (P=0·06) compared with high-GI diets. No changes were observed in HDL-cholesterol and triacylglycerol concentrations. No substantial heterogeneity was detected, suggesting that the effects of low-GI diets in these studies were uniform. Results of the present meta-analysis support the use of the GI as a scientifically based tool to enable selection of carbohydrate-containing foods to reduce total cholesterol and to improve overall metabolic control of diabetes
Evidence-based nutrition - using a meta-analysis to review the literature
No full textOne of the purposes of this series on evidence-based nutrition1,2 is to elucidate how students and researchers in nutrition, practitioners, health care providers and policy makers can apply basic principles and standardised methods to synthesise and make sense of large, often unmanageable amounts of information. This is necessary in order to draw conclusions from empirical studies and make decisions which will be evidence-based and not unduly influenced by bias and chance effects. The purpose of this paper in the series is to show how a meta-analysis can be used to do this by statistically combining results from independent but related studies into a composite measure of effect.A meta-analysis is a statistical technique used to combine the results of studies addressing the same question into a one number summary.3, 4 The meta-analysis method can be applied in the social-behavioural and biomedical sciences5 and is therefore particularly suitable for nutrition data. The term meta-analysis should not be confused with a systematic review. Egger and Smith4 suggest that the term meta-analysis should be used ‘to describe the statistical integration of separate studies whereas systematic review is most appropriate for denoting any review of a body of data that uses clearly defined methods and criteria’. According to this definition a meta-analysis can, if appropriate, be part of a systematic review. It is always appropriate and desirable to systematically review a body of data, but it may at times be inappropriate to pool results from separate studies.4 Because a systematic review is a structured, systematic qualitative and quantitative integration of comparable results of several independent studies, it can provide a firm basis for planning and policy recommendations.6 A meta-analysis has been described as ‘a quantitative approach to research reviews’,7 ‘aggregating data’,8 ‘the epidemiology of results’5 and ‘the application of statistical procedures to collections of empirical findings’.3 A meta-analysis uses specific statistical methods to combine, summarise and integrate comparable results from different studies. The unit of observation is therefore the study. A major purpose of pooling results in a meta-analysis is to increase statistical power and precision of estimates in smaller studies.3-9 There are excellent sources available3-10 with detailed, step-by-step guidelines, recommendations and numerous examples of how to do a meta-analysis. In this paper the advantages and limitations of a meta-analysis and the process of conducting one will be outlined briefly to motivate nutritionists when and how to use it in their interpretation of the literature, in drawing conclusions from studies with conflicting results, and in policy formulation
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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