Background
Major concerns have been expressed about the nature of the carbohydrate foods consumed by the general public and the long-term impact on chronic disease and all-cause mortality. However, fruits, vegetables, whole-grain cereals and legumes are important sources of dietary carbohydrates that are promoted for the health benefits. These low glycemic index (GI) foods raise the blood glucose less after eating a meal containing them than more refined carbohydrate foods. The question therefore is, does their habitual consumption lower the risk or incidence of the chronic diseases, such as diabetes, cardiovascular disease and diabetes-related cancers?
Aims
To determine if consumption of a diet that has a higher compared to a lower GI is associated with an increased risk of major chronic diseases, including diabetes, cardiovascular disease and diabetes-related cancers, and all-cause mortality.
Scientific Rationale
Currently, studies are divided on whether the GI of the diet relates to health outcomes. Nevertheless the total number of studies undertaken has been small compared, for example, to dietary fibre where a large number of studies are available and a strongly protective association against many chronic diseases has been demonstrated. In this respect, the UK Biobank data would provide the largest data set used so far to explore these necessary associations and, importantly, also contains data on a very wide range of other measurements (covariates) to include in the statistical model to control for potential confounding. Furthermore, the one-day diet histories of the UK Biobank lend themselves to a categorical glycemic index assessment we have developed that focusses on 7 food categories.
Duration
We will organize the data using the categorical glycemic index values of the diets within nine months and over the following two years, we will publish on the associations of glycemic index and glycemic load (GI x dietary carb x100) with diabetes, CVD, cancer and mortality outcomes.
Public health impact
Low glycemic index diets are advocated in a number of jurisdictions as part of the treatment of diabetes. Positive data from the proposed study will greatly strengthen the association with diabetes and establish the relationship with CVD, diabetes-related cancer, and all-cause mortality. These data will also reinforce the rationale behind current public health dietary advice to eat more fruits, vegetables and legumes as low glycemic index foods, and support the transition to more plant-based diets, as is now generally advised, which contain these low glycemic index foods.