Purpose: Lipid intakes such as saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids have been widely studied regarding cardiovascular health, but their relevance to cancer is unclear. Inconsistent epidemiological results may be explained by varied mechanisms involving PUFAs and redox balance, inflammatory status and cell signalling, along with interactions with other dietary components such as antioxidants, dietary fibre and more generally fruits and vegetable intakes. Therefore, this study aimed to investigate the associations between lipid intakes and cancer risk, and their potential modulation by vitamin C, vitamin E, dietary fibre and fruit and vegetable intakes.
Methods: This prospective study included 44,039 participants aged ≥ 45 years from the NutriNet-Santé cohort (2009-2017). Dietary data were collected using repeated 24 h-dietary records. Multivariable Cox models were performed to characterize associations.
Results: SFA intake was associated with increased overall [n = 1722 cases, HRQ5vsQ1 = 1.44 (1.10-1.87), p-trend = 0.008] and breast [n = 545 cases, HRQ5vsQ1 = 1.98 (1.24-3.17), p-trend = 0.01] cancer risks. n-6 PUFA [HRQ5vsQ1 = 0.56 (0.32-0.97), p-trend = 0.01] and MUFA (HRQ5vsQ1 = 0.41 [0.18-0.0.95), p-trend = 0.009] intakes were associated with a decreased risk of digestive cancers (n = 190 cases). Associations between n-6 PUFA, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) intakes and digestive cancer risk were modulated by dietary fibre, vitamin C and fruit and vegetable intakes.
Conclusion: These findings suggested that SFA intake could increase overall and breast cancer risks while some unsaturated fatty acids could decrease digestive cancer risk. However, in line with mechanistic hypotheses, our results suggest that intakes of fruits and vegetables and their constituents (antioxidants, fibre) may interact with PUFAs to modulate these associations.
Keywords: Antioxidants; Cancer risk; Lipids; PUFAs; Prospective cohort; Saturated fatty acids.