Population Nutrition

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The aim of the work within Population Nutrition Research (PNR) is to identify diet-disease relationships through the assessment of dietary intakes and health outcomes of populations.

Led by Dr Ziad Abdeen, this is achieved through the creation and maintenance of comprehensive and contemporary food composition databases, the development of innovative dietary assessment and statistical tools, and provision of guidance to collaborators on the appropriate use of dietary methodologies.

PNR specializes in dietary assessment using dietary records or recalls and the analysis of dietary data, in terms of food and nutrient intakes and dietary patterns and behaviors. PNR collaborates with other research groups to provide dietary assessment and analysis expertise for studies of all types and sizes from intervention studies to national surveys.

The work of the PNR group is summarized in the figure below, which illustrates the interface of the methodological aspects of the work and its public health significance.



Current Projects

1- Food Composition Databases

When conducting dietary assessment, there is a need for an up to date food composition database to translate the record of foods consumed into intake of nutrients. The basis for the nutrient content of foods in Palestine is primarily based on the USDA food composition database, modified appropriately with reference to local food composition tables, and supplemented with recipes of locally eaten mixed dishes. The Composition of Foods has an extensive list of foods, but it cannot keep up-to-date with all the products now available in the supermarket. In PNR our food composition experts are continually updating our database to incorporate many additional foods via recipe calculations and the use of manufacturers’ ingredient information. Current collaborative studies in PNR on infants and young children, require specific additions to the database to include foods eaten by these groups.
Data are available for macro and micronutrients and food constituents are added as required by new research hypotheses on the aetiology and prevention of cardiovascular, bone and other degenerative diseases. We are also disaggregating many mixed dishes to be able to calculate consumption of meat and fruit and vegetables accurately, which is important for finding out if dietary recommendations are being met.

2-Dietary assessment methodologies

PNR is continually advancing dietary assessment methods in order to obtain the most accurate information as possible from study participants. Our most common dietary assessment methodology is the estimated (unweighed) diet diary, where subject participants record food and drinks consumed over a period of several days. In recent years, we have made efforts to capture the social and cultural factors influencing food quality and quantity, and by developing food diaries where information about the socio-ecological environment of the foods consumed are recorded.
Many individuals, particularly children, find it hard to describe the food they have eaten, either in terms of content or portion size. New technologies are emerging in the field to enable photographs to be taken of the foods consumed, and in some cases, handheld devices to record information either verbally or in text. PNR has undertaken a pilot study to investigate the feasibility and usefulness of giving children digital cameras alongside their diaries to take photographs of the food items consumed. This pilot study has shown that digital photography can enhance the accuracy of the diet record by providing more detail on types and amounts of foods eaten than the diary alone.

3-Dietary analysis statistics and modelling

Traditional nutritional epidemiology relates intakes of single nutrients and foods in food groups to health outcomes. In recent years there has been a move to explore the overall diet in terms of diet the patterns of foods consumed together. Dietary pattern analysis has emerged with a number of approaches such as principal component analysis (PCA), cluster analysis, and reduced rank regression (RRR). There is also increasing interest in the way food is eaten, in terms of eating frequency, timing of eating and meal skipping, for example, in relation to health. PNR has been investigating these various approaches and establishing methods for compiling the dietary data to explore them. In longitudinal studies, tracking of dietary intakes and behaviours may also be important and a thorough investigation of tracking methods, their advantages and limitations has been undertaken. Work has also been done on developing an algorithm for available iron, taking into account food constituents that improve or limit iron absorption.

4-National Nutrition And Health Examination Survey

Introduction:

The National Nutrition and Health Examination Survey (NNAHES) is designed to assess the dietary habits and nutritional status of adults and children in Palestine. The survey is unique in that it provides data on dietary intake, nutritional and health status in a representative sample of the population.
The survey is carried out by a consortium comprising the following two organisations:

The NNAHES gathers quantitative and qualitative information on the dietary habits and nutritional status of a representative sample of the Palestinian population, comprising between 4000 and 4500 individuals every ten years. Adults and children aged 5 years and above are being recruited from the West Bank and Gaza.

Survey Contents

The survey combines computer assisted personal interviews (CAPI) and self-completion questionnaires with an examination component. All survey components are carried out in the respondent’s home.

The NNAHES interview collects data on:

The food intake data is collected using an estimated (unweighed) food diary.

The examination component consists of anthropometric and blood pressure measurements and urine and blood collections for various laboratory tests. Clinical relevant results are reported back to the respondents themselves and/or their doctors as requested on consent to participation.

A new feature of the NNAHES is to provide feedback to respondents about their diet within 3 to 4 months of participation in the survey.

The following nutrients were selected for feedback:


PNR’s role within the NNAHES

PNR is responsible for 5 different elements in the NNAHES rolling programme:

A dedicated team of about 19 staff split between the 4 different areas of work support the NNAHES at HNR.

Uses of the data

Key Survey Objectives can be summarized as follows:

PNR conducts additional investigations to explore the NNAHES dataset in more detail to address issues of strategic importance for our research or on behalf of our collaborators. This may include the analysis of the diet or nutritional status of specific subgroups, examining the relationship between specific nutrients or foods on health outcomes and modelling the impact of reformulation or wider dietary change on the nation’s health.

The survey data are also a resource for further analyses and the biological specimen residues can provide a valuable starting point for further research studies, linked to the survey.