Whole-grain products and whole-grain types are associated with lower all-cause and cause-specific mortality in the Scandinavian HELGA cohort

Abstract

No study has yet investigated the intake of different types of whole grain (WG) in relation to all-cause and cause-specific mortality in a healthy population. The aim of the present study was to investigate the intake of WG products and WG types in relation to all-cause and cause-specific mortality in a large Scandinavian HELGA cohort that, in 1992-8, included 120 010 cohort members aged 30-64 years from the Norwegian Women and Cancer Study, the Northern Sweden Health and Disease Study, and the Danish Diet Cancer and Health Study. Participants filled in a FFQ from which data on the intake of WG products were extracted. The estimation of daily intake of WG cereal types was based on country-specific products and recipes. Mortality rate ratios (MRR) and 95 % CI were estimated using the Cox proportional hazards model. A total of 3658 women and 4181 men died during the follow-up (end of follow-up was 15 April 2008 in the Danish sub-cohort, 15 December 2009 in the Norwegian sub-cohort and 15 February 2009 in the Swedish sub-cohort). In the analyses of continuous WG variables, we found lower all-cause mortality with higher intake of total WG products (women: MRR 0.89 (95 % CI 0.86, 0.91); men: MRR 0.89 (95 % CI 0.86, 0.91) for a doubling of intake). In particular, intake of breakfast cereals and non-white bread was associated with lower mortality. We also found lower all-cause mortality with total intake of different WG types (women: MRR 0.88 (95 % CI 0.86, 0.92); men: MRR 0.88 (95 % CI 0.86, 0.91) for a doubling of intake). In particular, WG oat, rye and wheat were associated with lower mortality. The associations were found in both women and men and for different causes of deaths. In the analyses of quartiles of WG intake in relation to all-cause mortality, we found lower mortality in the highest quartile compared with the lowest for breakfast cereals, non-white bread, total WG products, oat, rye (only men), wheat and total WG types. The MRR for highest v. lowest quartile of intake of total WG products was 0.68 (95 % CI 0.62, 0.75, P trend over quartiles< 0.0001) for women and 0.75 (95 % CI 0.68, 0.81, P trend over quartiles< 0.0001) for men. The MRR for highest v. lowest quartile of intake of total WG types was 0.74 (95 % CI 0.67, 0.81, P trend over quartiles< 0.0001) for women and 0.75 (95 % CI 0.68, 0.82, P trend over quartiles< 0.0001) for men. Despite lower statistical power, the analyses of cause-specific mortality according to quartiles of WG intake supported these results. In conclusion, higher intake of WG products and WG types was associated with lower mortality among participants in the HELGA cohort. The study indicates that intake of WG is an important aspect of diet in preventing early death in Scandinavia.