Association of dietary grain fibre and its main subtypes with essential hypertension risk: a prospective cohort study

This study investigated the relationships of total dietary grain fibre (TGF) and its two subtypes (whole-grain fibre (WGF) and refined grain fibre (RGF)) with essential hypertension (EHP) in a large-scale prospective cohort study. The participants were recruited by UK Biobank. Dietary grain fibre was assessed using the baseline touchscreen FFQ. New-onset EHP was defined by International Classification of Disease version 10. Cox proportional hazards model and restricted cubic spline analysis were utilised to examine the associations of TGF and its subtypes with EHP. Additionally, mediation analysis was applied to assess whether the triglyceride-glucose (TyG) index and inflammatory index score (INFLA-score) mediated these associations. Among 60 315 participants without prior hypertension, 3651 (6·05 %) developed EHP over a median follow-up of 10·3 years, with an incidence density of 6·08 per 1000 person-years. The adjusted hazard ratios for Q4 compared with Q1 were 0·828 (95 % CI: 0·750, 0·914) for TGF and 0·842 (95 % CI: 0·767, 0·936) for WGF. Restricted cubic spline analysis confirmed inverse relationships for TGF and WGF with EHP risk. But RGF showed no significant association with EHP. The TyG index and INFLA-score partially mediated the associations of TGF and WGF with EHP, with mediation proportions of 4·2 % and 3·3 % for TGF, and 4·9 % and 5·2 % for WGF, respectively. Jointly, TyG index and INFLA-score together mediated 5·6 % between TGF and EHP, and 7·4 % between WGF and EHP. In conclusion, higher intake of TGF and WGF reduces EHP risk, and this effect is only partly mediated by TyG index and INFLA-score.