Fiber from whole grains, but not refined grains, is inversely associated with all-cause mortality in older women: The Iowa Women’s Health Study

Summary

This prospective cohort study of postmenopausal women in Iowa found that consumption of whole grain fibre was inversely associated with all-cause mortality, whereas refined grain fibre showed no protective effect. Women consuming approximately 4.7 g whole grain fibre and 1.9 g refined grain fibre per 2,000 kcal had a 17% lower mortality rate compared to those with predominantly refined grain fibre intake. The findings highlight the importance of distinguishing fibre sources in epidemiological research and public health recommendations, as phytochemical content in whole grains likely explains differential health outcomes.

Regional applicability

This United States–based study provides strong epidemiological evidence relevant to United Kingdom dietary policy and practice, particularly regarding whole grain recommendations for older women. The findings directly support UK dietary guidelines emphasising whole grain consumption and could inform public health messaging around refined versus whole grain products in the British food environment.

Key measures

Whole grain fibre intake (g/2,000 kcal), refined grain fibre intake (g/2,000 kcal), all-cause mortality rate (relative risk with 95% confidence intervals), proportional hazards regression

Outcomes reported

The study examined the association between whole grain versus refined grain fibre intake and all-cause mortality risk in postmenopausal women over an 11-year follow-up period. A total of 1,341 deaths were recorded among 11,040 women during 124,823 observed woman-years.

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