Dietary supplementation and physical activity in cancer patients: A cross-sectional study in integrative oncology

Background: Dietary supplements (DS) and adapted physical activity (PA) are recognized as complementary strategies in oncology; however, guidelines for DS use during cancer treatment are lacking. Many patients self-prescribe DS and their adherence to PA guidelines remains low. Combined integrative approaches, such as supplementation and exercise, can induce synergistic effects rather than each intervention alone. This study investigated patterns of DS behavior across cancer phases. Understanding the potential link between motivations for DS and interest in PA may provide insights into the design of multidisciplinary approaches for oncology patients, with the goal of enhancing their quality of life. Methods: A cross-sectional study was conducted among 114 cancer patients using DS (106 women, 8 men), 27-79 years. Clinical data, DS behavior, and PA interest and levels (according to international guidelines) were collected by self-administered questionnaire. Descriptive statistics and chi-square tests were used. An exploratory binary logistic regression examined the association between DS behaviors and interest in PA. Results: Vitamin D and magnesium were the most used DS across all treatment phases, while olive oil and vitamin C were frequently reported during active treatment. Although oncologists were the preferred counselling source (59.6%), the main recommendations came from naturopaths, general practitioners, and personal networks. 38.6% of participants self-prescribed DS. Self-prescription was significantly associated with reasons for not informing general practitioners about DS use (chi(2)=10.371, p = 0.016). Interest in structured PA programs was higher among patients using DS for general strengthening, dietary support, and sleep (p < 0.05), but not among those using DS for fatigue, stress, or anxiety. Conclusion: Among DS users, self-prescription was common despite a clear preference for oncologist guidance. Many patients rely on non-medical sources. The observed association between motivations for DS use and interest in PA highlights the need to further investigate the impact of integrated supportive care strategies in oncology.