Vegetarian Diets Linked to Lower CKD Risk in UK Biobank
Key Takeaways
- In the UK Biobank cohort of 416,584 adults recruited in Wales, Scotland, and England, vegetarian dietary patterns were associated with significantly lower incident CKD risk than high meat intake.
- Low meat eaters also had significantly lower CKD risk than high meat eaters, and the strongest relative reduction was seen in vegetarians.
- The lower-risk signal for vegetarian diets remained directionally similar in subgroup and sensitivity analyses.
- Because these findings came from an observational UK cohort with baseline diet self-report and hospital-based CKD ascertainment, causation and broad generalizability remain limited.
Investigators conducted a UK Biobank prospective cohort analysis of vegetarian dietary patterns and incident CKD among adults aged 40 to 69 years, with a final analytical cohort of 416,584 after exclusions. Habitual diet was classified at baseline with a touchscreen food frequency questionnaire (FFQ) into high meat eaters, low meat eaters, poultry eaters, pescatarians, and vegetarians, with vegans merged into the vegetarian category because the vegan group was too small for separate robust analysis. Incident CKD was identified with hospital International Classification of Diseases, Tenth Revision and OPCS Classification of Interventions and Procedures, version 4 data, and multivariable Cox proportional hazards models used high meat eaters as the reference group while adjusting for sociodemographic, lifestyle, and clinical covariates. Recruitment spanned Wales, Scotland, and England.
During a mean follow-up of 12.9 years, 23,084 participants developed CKD. In the fully adjusted primary model, vegetarians had a lower incident CKD risk than high meat eaters, with HR 0.81, 95% CI 0.711–0.927. This was the strongest relative reduction in the primary model.
Low meat eaters also had a lower CKD risk than high meat eaters in the fully adjusted analysis, with HR 0.97, 95% CI 0.943–0.996. Investigators described a broader gradient toward lower CKD risk across dietary groups with less animal-food intake. The vegetarian association also persisted among participants with normal baseline kidney function, and subgroup and sensitivity analyses remained directionally similar after additional adjustment for baseline estimated glomerular filtration rate (eGFR), albumin-creatinine ratio (ACR), and polygenic risk. The pescatarian association reached statistical significance only after polygenic-risk adjustment.
The authors cautioned against causal interpretation because the analysis was observational and dietary pattern may track with broader lifestyle profiles despite multivariable adjustment. They also noted that diet was self-reported at a single baseline time point, that the dietary categories mixed frequency-based and exclusion-based definitions, that hospital-based CKD ascertainment may preferentially capture clinically recognized or more advanced disease, and that early CKD subgroup classification relied on single baseline kidney measures. The cohort was also healthier than the general UK population and predominantly White European. These findings are best read as UK cohort data rather than a direct estimate for North American populations.
According to the investigators, vegetarian dietary patterns, and to a smaller extent low meat intake, were associated with lower incident CKD relative to high meat intake in this UK cohort, while causal questions remain open.
Clinician Questions
How were the diet groups defined in the UK Biobank CKD analysis?
Habitual diet was classified at baseline with a touchscreen FFQ into high meat eaters, low meat eaters, poultry eaters, pescatarians, vegetarians, and initially vegans. High meat eaters consumed red or processed meat, including poultry, more than 5–6 times per week; low meat eaters consumed those foods less often but more than once weekly; poultry eaters consumed poultry but not red or processed meat; pescatarians excluded meat and poultry but included fish; vegetarians excluded meat and fish; and vegans reported no animal-derived foods. Vegans were merged with vegetarians because the vegan subgroup was too small for robust separate analysis.
How was incident CKD identified in the UK Biobank diet study?
Incident CKD was identified from hospital inpatient International Classification of Diseases, Tenth Revision diagnostic codes and OPCS Classification of Interventions and Procedures, version 4 procedure codes. Prevalent CKD at baseline was defined by prior diagnosis information or baseline estimated glomerular filtration rate below 60 mL/min/1.73 m². That hospital-based ascertainment approach is more likely to capture clinically recognized or more advanced CKD than every incident case in the community.
Did the vegetarian association differ by baseline kidney function or genetic risk for CKD?
The lower CKD risk associated with vegetarian diets was seen among participants with normal baseline kidney function; no significant association was observed in those with CKD stages 1–2, although heterogeneity between kidney-function strata was not significant. Analyses across sex, body mass index, education, ethnicity, and polygenic-risk strata were directionally similar without significant heterogeneity. The investigators also noted that estimates among Asian and Black participants were less precise because those subgroups were smaller.
How directly do these findings apply to U.S. adults at risk for CKD?
These findings describe a cohort recruited in Wales, Scotland, and England that had a generally healthier profile than the overall UK population and consisted predominantly of White European participants. The reported associations therefore do not directly define the same magnitude of CKD risk difference in more diverse U.S. adult populations.