Assessment of dietary and physical activity behaviours that are comparable between locations and over time are central to enabling our global public health work.

Diet and physical activity are both complex and challenging to measure. The MRC Epidemiology Unit is making significant contributions to methods and techniques for accurately and objectively measuring these behaviours and how they relate to Non-Communicable Disease risk. Expertise developed in high income settings is being applied with collaborators in low and middle income countries.

In addition to objective measurements of diet and physical activity, validated subjective measures, such as self-completion questionnaires, interview schedules and diaries, will also be important in describing trends over time and differences between settings.

Physical Activity

The Physical Activity group is collaborating internationally on the objective assessment of physical activity levels and patterns in adults, using their expertise with the Actiheart (combined heart rate and movement sensing) in several parts of the world, including Cameroon, Alaska and Barbados. The Behavioural Epidemiology Group is leading a collaboration of objectively assessed physical activity in children, based on the use of the Actigraph within the International Children’s Accelerometry Database (ICAD).

Studies include:

• Cameroon Study. The aims of this study were to validate feasible methods for measuring physical activity in population-based studies in Africa and to describe the physical activity levels and its determinants in an urban and a rural Cameroonian population. A follow-up study funded by the Wellcome Trust is nearing completion in the same locations in which detailed information on the determinants of physical activity is being collected. Read more.
• Physical activity and NCD risk, Caribbean. This study is the first objective assessment, using combined heart rate monitoring and accelerometry, of levels and patterns of physical activity in a population based sample of adults in the Caribbean. This work is nested in a population based survey in Barbados of diabetes, cardiovascular disease, and their social, biological and behavioural risk factors. Three hundred and eighty adults aged 25 to 54 participated in the objective assessment of physical activity. Data analysis is in progress, and will address levels, patterns and predictors of physical activity. The data will enable estimates of the contribution of physical inactivity to the risk of diabetes and cardiovascular disease. The collaboration is supporting the development at UWI of expertise in state of the art physical activity assessment, and the joint supervision of a UWI PhD candidate. This work is largely funded by the Ministry of Health of Barbados, with the MRC Epidemiology Unit providing the hardware and software for the assessment of physical activity, and ongoing expert guidance. Soren Brage and Kate Westgate are assisting in the study.

Diet

The Nutritional Epidemiology group has considerable expertise in the use of biomarkers to assess aspects of diet, such as investigating the relationship between different types of blood saturated fatty acid concentrations and the risk of diabetes, or the use of plasma vitamin C as a marker of fruit and vegetable intake. Most of this work has been conducted in the UK and Europe, although there is currently collaborative work with the University of the West Indies to assess sodium and potassium intake in Barbados.

Studies include:

• Assessment of sodium intake and dietary quality, Caribbean. High levels of hypertension in the Caribbean are thought to be related in part to high levels of salt consumption. However, objective data on sodium intake in the Caribbean are rare, as are robust dietary data to indicate sources of sodium in the diet and overall dietary quality. The Ministry of Health in Barbados has funded a study in which a representative sample of 400 adults, aged 25 to 64 years, are providing 24 hour urine samples for the measurement of sodium and potassium. In addition, detailed dietary data are being collected on all participants, using repeated 24 hour recalls. The MRC Epidemiology Unit is providing expert guidance on the analysis and interpretation of these data, and contributing to the joint supervision the UWI PhD candidate on this topic. Nita Forouhi is supporting the assessment.