Fig. 1: Schematic of follow-up, exposure, and covariate timing for the primary and sensitivity analyses.

The analyses are depicted for a hypothetical individual diagnosed in 1997, who died from prostate cancer in 2013. Dietary information in years lacking a food frequency questionnaire was carried forward from prior years. The exception was the transition from pre- to post-diagnosis; if the first questionnaire administered after diagnosis did not include a food frequency questionnaire, then dietary data were considered missing. The analyses corresponding to Table 3 and Supplementary Table 2 started follow-up at the time of diagnosis and lagged exposure by 4–6 years. The analyses corresponding to Supplementary Table 3 started follow-up at the time of diagnosis and did not lag exposure. The analyses corresponding to Supplementary Table 4 started follow-up at the time of first post-diagnosis questionnaire with all score components and anchored exposure at first post-diagnostic health behaviour scores without updating. The analyses corresponding to Supplementary Table 5 started follow-up 4–6 years after the first post-diagnosis questionnaire with all score components and lagged exposure 4–6 years.