{"entity":{"id":"dietary-supplements-treatment-interactions","kind":"technology","name":"Dietary supplements during cancer treatment: interactions and harms","aka":[],"tldr":"Most people on cancer treatment take supplements, often without telling their team. Antioxidants, St John's wort, high-dose vitamins and some herbs can blunt chemotherapy or radiotherapy or interact with targeted drugs.","summary":"Surveys find 60-80% of patients use dietary supplements during treatment and roughly half do not disclose it. Evidence of harm is strongest for: antioxidant supplements (vitamins A, C, E, carotenoids, coenzyme Q10) during chemotherapy and radiotherapy, associated with higher recurrence and death in the DELCaP cohort within a breast cancer chemotherapy trial (JCO 2020: recurrence HR 1.41) and with worse outcomes in head and neck cancer radiotherapy (randomised, beta-carotene plus vitamin E); beta-carotene increasing lung cancer in smokers (ATBC, CARET randomised trials); vitamin E and selenium increasing prostate cancer in SELECT; St John's wort inducing CYP3A4 and reducing exposure to irinotecan, imatinib and many tyrosine kinase inhibitors; and high-dose vitamin B12 and B6 associated with lung cancer in men. Iron and vitamin B12 during checkpoint or targeted therapy are usually harmless; green tea extract and kava carry hepatotoxicity risk that confounds drug-induced liver injury assessment. Memorial Sloan Kettering's About Herbs database and pharmacist-led medication reconciliation that includes supplements are the practical tools.","status":"established","asOf":"2026-09-08","wikipedia":"https://en.wikipedia.org/wiki/Dietary_supplement","links":[{"label":"DELCaP: supplements during chemotherapy (JCO 2020)","url":"https://doi.org/10.1200/JCO.19.01203"},{"label":"MSK About Herbs database","url":"https://www.mskcc.org/cancer-care/diagnosis-treatment/symptom-management/integrative-medicine/herbs"}],"tags":[],"related":["idea-moon-supplement-interaction-database","idea-nl-antioxidant-supplement-harm-confirmation"],"cancers":["breast-hr-positive","tnbc","head-and-neck","nsclc","prostate","colorectal"],"sections":["nutrition-lifestyle","supportive-care"],"technologies":["cytotoxic-chemotherapy","nutrition-screening-mnt","soy-breast-cancer"],"targets":[],"drugs":["irinotecan","paclitaxel","doxorubicin"],"companies":[],"institutions":["mskcc"],"pathways":[],"terms":["unproven-diet-claims"],"trials":[],"people":[],"bottlenecks":["b-misinformation","b-toxicity-qol"],"keyPapers":["paper-ambrosone-j-clin-oncol"],"journals":[],"dependsOn":[],"notes":[],"principle":"Antioxidants can neutralise the reactive oxygen species through which radiotherapy and many cytotoxics kill cells; herbal constituents induce or inhibit CYP450 enzymes and drug transporters, altering the exposure of oral anticancer drugs.","strengths":["Randomised evidence of harm for several supplements","Interaction databases and pharmacist review are cheap fixes","Disclosure improves with routine, non-judgemental asking"],"limitations":["Most supplement evidence is observational","Products vary in content and contamination","Regulatory oversight is weak in most countries"]},"route":"/technologies/dietary-supplements-treatment-interactions/","neighbours":{"idea":[{"id":"idea-moon-supplement-interaction-database","kind":"idea","name":"An open supplement-drug interaction checker built into oncology prescribing","route":"/ideas/idea-moon-supplement-interaction-database/"},{"id":"idea-nl-ask-about-diet-prebunking","kind":"idea","name":"Ask about diet at diagnosis, and prebunk the myths before the internet does","route":"/ideas/idea-nl-ask-about-diet-prebunking/"},{"id":"idea-nl-antioxidant-supplement-harm-confirmation","kind":"idea","name":"Confirm or refute the harm of antioxidant supplements during chemotherapy","route":"/ideas/idea-nl-antioxidant-supplement-harm-confirmation/"}],"cancer":[{"id":"colorectal","kind":"cancer","name":"Colorectal cancer","route":"/cancers/colorectal/"},{"id":"head-and-neck","kind":"cancer","name":"Head and neck squamous cell carcinoma","route":"/cancers/head-and-neck/"},{"id":"breast-hr-positive","kind":"cancer","name":"HR-positive / HER2-negative breast cancer","route":"/cancers/breast-hr-positive/"},{"id":"nsclc","kind":"cancer","name":"Non-small-cell lung cancer","route":"/cancers/nsclc/"},{"id":"prostate","kind":"cancer","name":"Prostate cancer","route":"/cancers/prostate/"},{"id":"tnbc","kind":"cancer","name":"Triple-negative breast cancer (TNBC)","route":"/cancers/tnbc/"}],"section":[{"id":"nutrition-lifestyle","kind":"section","name":"Diet, Exercise & Lifestyle","route":"/fronts/nutrition-lifestyle/"},{"id":"supportive-care","kind":"section","name":"Supportive Care & Survivorship","route":"/fronts/supportive-care/"}],"technology":[{"id":"american-ginseng-fatigue","kind":"technology","name":"American ginseng for cancer-related fatigue","route":"/technologies/american-ginseng-fatigue/"},{"id":"ayurvedic-medicine-cancer","kind":"technology","name":"Ayurvedic medicine and cancer","route":"/technologies/ayurvedic-medicine-cancer/"},{"id":"cannabinoids-pain-appetite","kind":"technology","name":"Cannabis and cannabinoids for pain, appetite and cancer control","route":"/technologies/cannabinoids-pain-appetite/"},{"id":"curcumin-turmeric","kind":"technology","name":"Curcumin and turmeric","route":"/technologies/curcumin-turmeric/"},{"id":"cytotoxic-chemotherapy","kind":"technology","name":"Cytotoxic chemotherapy","route":"/technologies/cytotoxic-chemotherapy/"},{"id":"green-tea-egcg","kind":"technology","name":"Green tea and EGCG extracts","route":"/technologies/green-tea-egcg/"},{"id":"medicinal-mushrooms-reishi-turkey-tail","kind":"technology","name":"Medicinal mushrooms: reishi, turkey tail, shiitake and others","route":"/technologies/medicinal-mushrooms-reishi-turkey-tail/"},{"id":"melatonin-cancer","kind":"technology","name":"Melatonin as a cancer adjunct","route":"/technologies/melatonin-cancer/"},{"id":"nutrition-screening-mnt","kind":"technology","name":"Oncology nutrition assessment and medical nutrition therapy","route":"/technologies/nutrition-screening-mnt/"},{"id":"soy-breast-cancer","kind":"technology","name":"Soy foods and breast cancer","route":"/technologies/soy-breast-cancer/"},{"id":"st-johns-wort-interaction","kind":"technology","name":"St John's wort: an interaction to avoid","route":"/technologies/st-johns-wort-interaction/"},{"id":"hair-supplements-marketed","kind":"technology","name":"Supplements sold for hair growth after cancer treatment","route":"/technologies/hair-supplements-marketed/"},{"id":"traditional-chinese-herbal-medicine","kind":"technology","name":"Traditional Chinese herbal medicine alongside treatment","route":"/technologies/traditional-chinese-herbal-medicine/"}],"drug":[{"id":"doxorubicin","kind":"drug","name":"Doxorubicin","route":"/drugs/doxorubicin/"},{"id":"irinotecan","kind":"drug","name":"Irinotecan (and liposomal irinotecan)","route":"/drugs/irinotecan/"},{"id":"paclitaxel","kind":"drug","name":"Paclitaxel / nab-paclitaxel","route":"/drugs/paclitaxel/"}],"institution":[{"id":"mskcc","kind":"institution","name":"Memorial Sloan Kettering Cancer Center","route":"/institutions/mskcc/"}],"term":[{"id":"unproven-diet-claims","kind":"term","name":"Unproven diet claims (alkaline, juice, 'anti-cancer' diets)","route":"/terms/unproven-diet-claims/"}],"bottleneck":[{"id":"b-misinformation","kind":"bottleneck","name":"Misinformation and unproven therapies","route":"/bottlenecks/b-misinformation/"},{"id":"b-toxicity-qol","kind":"bottleneck","name":"Toxicity and quality of life are undervalued","route":"/bottlenecks/b-toxicity-qol/"}],"paper":[{"id":"paper-ambrosone-j-clin-oncol","kind":"paper","name":"Dietary Supplement Use During Chemotherapy and Survival Outcomes of Patients With Breast Cancer Enrolled in a Cooperative Group Clinical Trial (SWOG S0221)","route":"/key-papers/paper-ambrosone-j-clin-oncol/"}],"roadmap":[{"id":"nutrition-lifestyle-roadmap","kind":"roadmap","name":"Diet, exercise and lifestyle roadmap: causes established → interventions that disappointed → exercise proven as treatment","route":"/roadmaps/nutrition-lifestyle-roadmap/"}]}}