Blood and Urine Collection and Analysis - Participants were asked to provide a blood sample, fasting where possible, and a first void morning urine sample. The samples were collected by a qualified nurse at designated centres within the survey area or in the respondent's home if the respondent could not travel. In total, five tubes (45mls) of blood were collected from respondents and where appropriate, inverted gently to ensure thorough mixing with anti-coagulant. Of these, four were kept chilled and transported to the lab for further processing and storage, while the fifth was kept at room temperature for full blood count analysis. The blood tubes collected were: 3 x serum tubes (total 26ml); 2 x ethylenediaminetetraacetic acid (EDTA) tubes (total 13ml); 1 x lithium heparin tube (6ml). A 50ml first void urine sample was also collected. Respondents were provided with a sterile collection tube to collect the urine sample on the final survey visit. They were also provided with an ice pack and asked to keep the sample chilled until they met with the nurse. Samples were kept on ice during transport to the lab for further processing. A blood collection form was completed in which the following was recorded: date and time of blood collection, whether the respondent was fasting or not and any irregularities during blood collection. Written consent to take a blood and urine sample was obtained along with consent for the survey at the initial visit. Blood and urine samples were collected for the analysis of a number of markers of nutritional status and metabolic health. In line with good ethical practice, all samples were anonymised prior to analysis.