Food colouring additives and cancer incidence in the NutriNet-Santé prospective cohort

Our study aimed to assess potential associations between food colouring additives and cancer incidence in the French NutriNet-Santé cohort. A total of 105,260 adults (78.3% females; mean age 42.0 ± 14.5y) without prevalent cancer and who completed ≥ 2 24-hour dietary records at baseline were followed for > 7 years. Dietary intakes were assessed using repeated brand-specific 24 h records, and cumulative time-dependent exposure to food additives was evaluated through multiple composition databases and ad-hoc laboratory assays in food matrices. Associations between exposures to food colouring additives (sex-specific tertiles if proportion of exposed participants > 2/3, or non-exposed/lower/higher exposed based on sex-specific median otherwise) and cancer incidence were assessed using multivariable Cox models. We identified 4,226 incident cancer cases (508 prostate, 1,208 breast [387 premenopausal and 821 postmenopausal], and 352 colorectal). Total food colouring additives were associated with higher overall [HR_{higher versus non/lower consumers} (95%CI): 1.14 (1.05-1.24); absolute risk at age 60: 13.3% (higher consumers) vs. 12.1% (lower/non-consumers)], breast [1.21 (1.03-1.42); 5.7%, 4.8%], and postmenopausal breast [1.32 (1.09-1.61); 14.9%, 12.5%] cancer incidence. After False Discovery Rate correction, only plain caramel (European code: E150a) was associated with overall cancer [1.15 (1.07-1.25); 14.0%, 12.1%] and beta-carotene (E160a) with overall [1.16 (1.07-1.25); 13.7%, 11.9%] and breast cancer [1.41 (1.23-1.62); 6.2%, 4.4%]. This study provides novel exploratory evidence linking colouring additives to cancer incidence. Further research is needed to elucidate underlying mechanisms. Findings support recommendations to limit exposure to non-essential food additives (i.e. used primarily for sensory or aesthetic purposes rather than for food safety or preservation) and inform regulatory reassessment.