Consumption of Whole Grains and Cardiometabolic Health

Abstract

Evidence from observational studies and intervention studies has shown inverse associations between whole grain consumption and risk of developing cardiometabolic diseases. Most studies to date have characterized whole grain intake as the sum of whole grain ingredients from all grain-containing foods which may contain diverse contents of whole grains and refined grains. Whether different whole grain foods may exert differential associations with cardiometabolic diseases remains unknown. This dissertation focuses on individual whole grain foods, including whole grain cold breakfast cereal, oatmeal, dark bread, brown rice, popcorn, wheat germ, and added bran, in relation to major cardiometabolic diseases including type 2 diabetes (T2D), coronary heart disease (CHD), and obesity. The first project investigated the associations between individual whole grain foods and risk of T2D. We conducted a prospective analysis examining the association between the seven individual whole grain foods and risk of T2D. We found higher consumption of total whole grains and most individual whole grain foods were significantly associated with a lower risk of T2D, whereas higher popcorn intake was associated with an increased risk of T2D. The second project evaluated whether heterogeneous associations existed for CHD risk among individual whole grain foods. We used proportional hazards models to estimate the association between individual whole grain foods and risk of CHD. Our results showed that higher intake of total whole grains and most individual whole grain foods were significantly associated with lower risk of CHD. Popcorn intake was not associated with CHD risk. The final project examined the change of individual whole grain foods intake in relation to long-term weight change. Multivariable generalized linear regression models were used to evaluate the association between the change of intake of whole grain foods and 4-year weight change over the same 4-year follow-up interval. Our findings suggested that increased consumption of most individual whole grain foods, especially in replacements of refined grains, was associated with less weight gain. This dissertation demonstrated overall beneficial associations between individual whole grain foods and risk of developing the cardiometabolic diseases. The data support the current dietary guidelines that encourage increased whole grain intake for better cardiometabolic health.