A secondary analysis examining the changes in dietary glycaemic index and glycaemic load in Australian children between 1995 - 2012

Dietary glycaemic index and dietary glycaemic load, as well as the major sources of dietary glycaemic load in 3 Australian population-based nutrition surveys, namely 1995 Australian National Nutrition Survey (1995NS), 2007 Australian National Children's Nutrition and Physical Activity Survey (2007NS) and 2011-12 National Nutrition and Physical Activity Survey (2012NS), were described. The 1995NS was conducted by the Australian Bureau of Statistics (ABS) and the Department of Health together with the 1995 National Health Survey. Data were collected between February 1995 and March 1996. Information about food and beverage intake, usual frequency of intake, eating habit, attitudes and physical measurements of Australians population aged 2 year-old or above was collected (n = 13,858) with a 61.4% response rate. Participants were selected randomly from dwellings in different State and Territories. Dietary intake was assessed using a single 24-hour recall, and a subset of the sample (76.2% of those aged 12 and over) also completed a food frequency questionnaire (FFQ). Children aged 15 to 16 years provided their own dietary recall while parents, guardians or close relatives were responsible for providing the information for children aged 14 years or below. Among all the participants in 1995NS, 2,729 (19.7%) were aged between 2 and 16 inclusively. For 2007NS, information on dietary intake, physical activities and demographic characteristics of randomly selected children and adolescents aged 2 to 16 years (n = 4,837) from all Australian states and territories were collected with a response rate of 40%. Data collection occurred between February 2007 and August 2007. Dietary data were collected using a 24-hour recall during face to face home visit, and the majority of the sample (n = 4,658) also completed a second 24-hour recall during a telephone interview conducted 7-21 days after the home visit. Care-givers provided dietary recall information for children aged 2 to 8 years while children of 9 years or above provided their own dietary recall. For 2012NS, respondents were randomly selected from 9,500 private dwellings across Australia except for very remote area and some non-private dwellings, e.g., hotels and hospitals. Dietary and physical activity information of the Australian population aged 2 years or above (n = 12,153) were collected from May 2011 to June 2012 from 12,366 dwellings with a 77% response rate. Dietary data were collected using a 24-hour recall during face to face home visit, and a second 24-hour recall during a telephone interview was collected in ~60% of subjects at least 8 days after the home visit. Adults were responsible for providing full food recall and physical activity question for children aged 2 to 5 years, while children aged 6 to 8 years can assist in the recall. Children aged 9 to 11 years were interviewed directly with adult assisting and children aged 12 to 14 years answered the questions themselves with adults in the same room. Those aged 15 – 17 years were interviewed personally with parental consent. Among all the participants in 2012NS, 2,548 (20.9%) were aged between 2 and 16 years inclusively. A published systematic method was used to assign glycemic index values to foods reported in the surveys. Dietary glycemic load is defined as the sum of the products of glycemic index (as %) and the amount of available carbohydrate in the reported serving of the foods, and dietary glycemic index is calculated as dietary GL divided by total amount of available carbohydrate in the diet.