**Background:** A suboptimal diet is a major risk factor for non-communicable chronic diseases (NCD). A diet low in fibre (defined as mean daily intake <23.5 g/d from all sources) has been linked to increased burdens of diabetes mellitus, stroke, colon and rectum cancer (CRC), and ischemic heart disease (IHD). Previous studies have shown that a 10 g/d increase in dietary fibre reduces IHD risk by 15% and CRC risk by 13%. However, the global burden of NCD attributable specifically to a low-fibre diet had not been systematically estimated. This study aimed to assess the burden across 204 countries and territories from 1990 to 2019.
**Methods:** All data were sourced from the Global Burden of Disease (GBD) Study 2019. Mortality, disability-adjusted life-years (DALY), and years lived with disability (YLD) were estimated using Bayesian geospatial regression (CODEm model) with 95% uncertainty intervals (UI). The comparative risk assessment framework was used to estimate population-attributable fractions (PAF). A diet low in fibre was defined as average daily consumption <23.5 g/d from all sources, adjusted for a 2000 kcal/d diet using a residual method. Outcomes included IHD (ICD-10: I20–I25), stroke (ischemic, intracerebral hemorrhage, subarachnoid hemorrhage), diabetes (E10–E14), and CRC (C18–C21). Age-standardized rates (ASR) per 100,000 population were calculated, and estimated annual percentage change (EAPC) with 95% CI was derived from linear regression of ln(ASR) over calendar year. Gaussian process regression explored the relationship between sociodemographic index (SDI) and ASMR/ASDR.
**Key Results:** Globally, ASMR attributable to a low-fibre diet declined from 14.84 (95% UI: 8.28, 21.43) to 7.74 (95% UI: 4.37, 11.32) per 100,000 from 1990 to 2019, with an EAPC of −2.39 (95% CI: −2.54, −2.24). ASDR declined from 331.12 (95% UI: 192.52, 473.01) to 186.89 (95% UI: 111.11, 268.42), EAPC −2.10 (95% CI: −2.25, −1.94). Age-standardized YLD rate declined from 24.95 (95% UI: 13.69, 37.72) to 22.08 (95% UI: 11.72, 34.33), EAPC −0.45 (95% CI: −0.49, −0.41). Males had higher ASMR and ASDR than females in both years, but lower age-standardized YLD rates. The burden increased with age. By SDI quintile, the high-SDI region had the lowest ASMR (4.64; 95% UI: 2.53, 6.76) and ASDR (105.06; 95% UI: 60.80, 149.92) in 2019, while the low-middle-SDI region had the highest (ASMR 12.67; 95% UI: 7.81, 17.96; ASDR 307.58; 95% UI: 191.05, 436.82). EAPC was lowest in high-SDI (−3.67; 95% CI: −3.82, −3.53) and highest (least negative) in low-SDI regions (−0.85; 95% CI: −1.09, −0.61). Notably, ASMR increased in Southern sub-Saharan Africa (from 4.07 to 4.60) and Central sub-Saharan Africa (from 7.46 to 9.34). The EAPC for ASMR in Australasia was the lowest at −4.76 (95% CI: −4.95, −4.57). Age-standardized YLD rates increased in several regions including Central sub-Saharan Africa (EAPC 1.49; 95% CI: 1.07, 1.91), High-income Asia Pacific (0.90; 95% CI: 0.83, 0.97), and Central Latin America (0.71; 95% CI: 0.62, 0.81). The burden from diabetes mellitus attributable to low-fibre diet increased in Central Asia, Southern sub-Saharan Africa, and Eastern Europe.
**Clinical Implications:** Despite global declines in age-standardized mortality and DALY rates, the absolute burden of NCD attributable to a low-fibre diet remains substantial and is increasing in several regions, particularly sub-Saharan Africa. The rising YLD rates, especially for diabetes, indicate that morbidity from low-fibre diets is an emerging concern even where mortality is declining. These findings support the need for population-level dietary interventions including mass media campaigns, educational initiatives, food pricing strategies (e.g., minimizing taxes on high-fibre foods), and region-specific public health policies. Early dietary interventions targeting younger males and cost-effective strategies for older males are particularly needed. The study is limited by potential data quality discrepancies across regions, use of universal effect sizes that may not apply to all population subgroups, and inherent measurement errors in dietary assessment.