ObjectivesWhole grain intake is associated with lower risk of cardiovascular disease (CVD) and related risk factors. Cereal fibre content of whole grains may be responsible, although it is not clear to what extent. Inconsistent definitions of whole grains used within previous studies, such as including bran as a whole grain source, confound findings and limit the ability to separate the two exposures. We compared how intakes of whole grain and cereal fibre were separately associated with markers of CVD risk in adult participants within the UK National Diet and Nutrition Survey (NDNS) and the Australian Health Survey (AHS).MethodsCross-sectional analyses of the NDNS Rolling Programme 2008–14 and the 2011–13 AHS examined associations between whole grain and cereal fibre intakes and markers of CVD risk using multivariate linear regression analysis. Whole grain was defined as containing the endosperm, germ and bran components in the expected proportions, and food composition databases were used to estimate intakes.ResultsWithin the NDNS, participants in the highest quartile (Q4) of whole grain intake had lower waist-hip ratio (Q1 0.872; Q4 0.857; P = 0.04), HbA1c (Q1 5.66%; Q4 5.47%; P = 0.01) and homocysteine (Q1 9.95 µmol/L; Q4 8.76 µmol/L; P = 0.01) compared to participants in the lowest quartile (Q1) after adjustment for cereal fibre intake. Participants in the highest tertile of whole grain intake within the AHS had lower waist circumferences (P = 0.03), HbA1c (P = 0.03) and fasting blood glucose (P = 0.048) compared to non-whole grain consumers after adjustment for cereal fibre intake. Cereal fibre intake, when analysed separately, was inversely associated with waist-hip ratio (P = 0.03) and homocysteine (P = 0.002) in the NDNS, and BMI (P < 0.0001) and waist circumference (P = 0.0008) in the AHS.ConclusionsSimilar inverse associations between whole grain and cereal fibre intakes to multiple markers of CVD risk suggest cereal fibre may play a role in protective associations of whole grains. However, whole grain associations often remained significant after adjustment for cereal fibre intake, suggesting additional constituents may be relevant. Future research should ensure use of consistent definitions when examining health associations of whole grains and their specific constituents.