The association of the dietary inflammatory potential with cancer risk remains uncertain. We examined the relationship of the dietary inflammatory potential with risk of overall and site-specific cancers and explored its sex and age differences.

A community-based longitudinal study.

Participants from the UK Biobank completed baseline surveys during 2006–2010 and were followed for up to 15 years to detect incident cancer.

170,899 cancer-free participants with dietary data available (mean age: 55.73 ± 7.95, 54.10% female).

At baseline, dietary intake was assessed with a 24-h dietary record for up to 5 times. The inflammatory diet index (IDI) was calculated to assess the dietary inflammatory potential as a weighted sum of 31 food groups (including 14 anti-inflammatory and 17 pro-inflammatory) based on plasma high-sensitivity C-reactive protein (hsCRP) levels, and tertiled as low (indicating low-inflammatory diet), moderate, and high IDI (as reference). Overall and site-specific cancers were ascertained via linkage to routine hospital admission, cancer registry, and death certificate data. Data were analyzed using Cox regression and Laplace regression.

During the follow-up (median 10.32 years, interquartile range: 9.95 to 11.14 years), 18,884 (11.05 %) participants developed cancer. In multi-adjusted Cox regression, low IDI scores were associated with decreased risk of rectal cancer (hazard ratio [95% confidence interval, CI] 0.76 [0.61, 0.94]), thyroid cancer [0.45 (0.27, 0.74)], lung cancer [0.73 (0.61, 0.88)]. However, the association between IDI score and the risk of overall cancer was not significant. Laplace regression analysis showed that 10th percentile differences (95% CIs) of cancer onset time for participants with low IDI scores was prolonged by 1.29 (0.32, 2.27), 1.44 (0.58, 2.30), and 2.62 (0.98, 4.27) years for rectal cancer, thyroid cancer, and lung cancer, respectively, compared to those with high IDI scores. Stratified analysis revealed that low IDI scores were associated with a lower risk of rectal cancer (p interaction between IDI score and sex = 0.035) and lung cancer in males, but not in females, and with a reduced risk of thyroid cancer in females, but not in males. Moreover, low IDI scores were associated with a reduced risk of rectal cancer and lung cancer in the participants aged ≥60 years, but not in those <60 years, and with a reduced risk of thyroid cancer in those aged ≥60 years and <60 years.

A low-inflammatory diet is associated with decreased risk and prolonged onset time of rectal cancer and lung cancer, especially among males and individuals aged ≥60 years, and thyroid cancer among females.