Soft drink intake and progression of radiographic knee osteoarthritis: data from the osteoarthritis initiative

Lu B, Ahmad O, Zhang FF, Driban JB, Duryea J, Lapane KL, McAlindon T, Eaton CB · BMJ Open

A dose-response in men and nothing in women — the mirror image of the same cohort's milk finding. Across none, ≤1, 2-4 and ≥5 soft drinks per week, adjusted mean loss of medial joint space width was 0.31, 0.39, 0.34 and 0.60 mm. The gradient was steeper in **non-obese** men; in obese men only the highest intake category separated from none. No association at any level in women. Adjusted for body mass index.

Population

2,149 Osteoarthritis Initiative participants with radiographic knee OA, followed to 48 months

Intervention

Baseline soft drink intake by Block Brief food-frequency questionnaire

Comparator

No soft drinks

Limitations

Observational, one baseline questionnaire, and the dose-response is not monotonic — 2-4 drinks a week showed less loss than ≤1. The finding is confined to one sex with no mechanism proposed for that, and the same research group's milk analysis in the same cohort found its effect only in the other sex. That the gradient is steeper in non-obese men argues against a straightforward weight route, and equally against a straightforward interpretation. Never replicated.