Food sources of dietary fibre and risk of total knee replacement related to severe osteoarthritis, the Singapore Chinese Health Study

Leung YY, Jin A, Tan KB, Ang LW, Yuan JM, Koh WP · RMD Open

A fibre study with a surgical endpoint, in a lean cohort where body weight has less room to do the explaining, and it does not agree with the American ones. Across 2,816 incident knee replacements, higher total fibre carried a higher risk in the demographic model (highest versus lowest quartile HR 1.18, 95% CI 1.05-1.32, p trend 0.003), settling at 1.11 (95% CI 0.99-1.24, p trend 0.088) once weight, activity, smoking and comorbidity were added. Among six food sources only legumes cleared the Bonferroni threshold the authors set for them: HR 0.86 (95% CI 0.76-0.96, p trend 0.004), stepwise across quartiles and unchanged by mutual adjustment for the other five. Nuts and seeds separated until the fuller model; grain products, soy food, fruits and vegetables did not. Body weight moves almost none of it — the legume estimate is 0.82 without BMI in the model and 0.86 with it, and the formal mediation analysis finds no indirect effect through BMI.

Population

63,129 of the 63,257 Singapore Chinese Health Study participants aged 45-74 at recruitment (1993-1998), linked to the national hospital discharge database through 2017, median follow-up 19.6 years

Intervention

Higher dietary fibre intake, and fibre by food source

Comparator

Lowest quartile

Limitations

Total knee replacement captures severe disease that reaches surgery, which is a different endpoint from symptomatic OA and is shaped by healthcare access. A single baseline questionnaire in 1993-1998 against operations through 2017, with height or weight self-reported and imputed for 16% of the cohort. Legumes are one food source among six, and they supply 0.8% of this cohort's dietary fibre — whatever that association is measuring, fibre intake is an unlikely candidate. Funded by the NIH and Singapore's National Medical Research Council, no declared competing interests.