Comparison of associations of intake of ultra-processed and non-ultra-processed whole-grain foods with cardiometabolic risk measures in Australian and US adults

Evidence suggests total ultra-processed food (UPF) consumption increases disease risk. As whole grains are health protective, their inclusion in UPF definitions warrants consideration. We aimed to quantify Australian and US whole-grain consumption by level of food processing and compare associations on cardiometabolic risk measures. A cross-sectional analysis of Australian (NNPAS 2011-12)(n = 7735) and US (NHANES 2015-18)(n = 8343) nationally representative 2d intake data. The Nova classification system determined levels of processing. Mean and median whole-grain intakes were estimated by processing level, and regression models were used to explore associations across tertiles for total, non-UPF (Nova 1-3) and UPF (Nova 4) whole-grain intakes with cardiometabolic risk measures. Adults median total whole-grain intake was 34.3 g/10 MJ/d (Australia) and 11.6 g/10 MJ/d (US). Mean whole-grain intake from UPF sources was higher in the US (71.0%) compared to Australia (48.9%). In Australia and the US, respectively, tertiles of non-UPF whole-grain intake were inversely associated with body weight (p = 0.02; p = 0.002), BMI (p = 0.001; p < 0.0001), waist circumference (p = 0.02; p = 0.001), waist-to-height ratio (WHR) (p = 0.003; p = 0.0001), and C-reactive protein (CRP) (p = 0.02; p = 0.0003), and for fasting plasma glucose (p = 0.002) in Australia only. UPF whole-grain intake was inversely associated with WHR (p = 0.04; p = 0.03) and diastolic blood pressure (p = 0.01; p = 0.03), as well as waist circumference (p = 0.0496) in Australia, and BMI (p = 0.03) and CRP (p = 0.02) in the US. Non-UPF whole-grain sources had stronger inverse associations than UPF sources. All whole grain foods should be promoted in public health and consumer messaging with emphasis on less processed sources given their greater observed benefit to cardiometabolic risk measures.