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Vitamin A from food matters, but supplements have not prevented lung cancer or lengthened survival in melanoma, and some studies link them to a higher risk of prostate cancer. Because it is stored in the body, high doses taken for months can damage the liver, and it must be avoided in pregnancy.
Memorial Sloan Kettering's About Herbs entry on vitamin A summarises the cancer evidence plainly: supplementation does not protect against non-small cell lung cancer or prolong survival in melanoma, and may raise the risk of prostate cancer, so the advice is to obtain vitamin A from food. Vitamin A is fat-soluble and accumulates. MSK describes chronic toxicity usually with intakes above 30,000 IU a day, with significant liver injury reported at doses as low as 20,000 IU and in regular drinkers; symptoms include nausea, headache, blurred vision and raised liver enzymes. Supplements are contraindicated in pregnancy because of the risk to the baby. Interactions listed by MSK: large doses may increase the effect of warfarin, and taking vitamin A with prescribed retinoids such as tretinoin, acitretin or bexarotene adds to their side effects. Prescribed retinoids used in oncology (all-trans retinoic acid in acute promyelocytic leukaemia, bexarotene in skin lymphoma) are drugs given under supervision and are a different matter from over-the-counter vitamin A.
Retinoic acid, the active metabolite, acts through nuclear retinoic acid and retinoid X receptors to drive cell differentiation, which is why prescribed retinoids work in some cancers; excess retinol is stored in the liver, where it becomes toxic.
Query for this technology: (TITLE:"Vitamin A supplements" OR ABSTRACT:"Vitamin A supplements" OR TITLE:"Retinol supplements" OR ABSTRACT:"Retinol supplements" OR TITLE:"Retinyl palmitate" OR ABSTRACT:"Retinyl palmitate") AND (cancer OR tumor OR tumour OR oncology OR carcinoma OR lymphoma OR leukemia OR leukaemia OR myeloma OR sarcoma OR melanoma OR glioma). Results are unfiltered search hits about Vitamin A supplements, not a curated reading list.
Shares Unproven diet claims (alkaline, juice, 'anti-cancer' diets), Dietary supplements during cancer treatment: interactions and harms, Evidence-based integrative oncology, Misinformation and unproven therapies and the tags complementary, supportive-care.
Shares Unproven diet claims (alkaline, juice, 'anti-cancer' diets), Dietary supplements during cancer treatment: interactions and harms, Evidence-based integrative oncology, Misinformation and unproven therapies and the tags complementary, supportive-care.
Shares Unproven diet claims (alkaline, juice, 'anti-cancer' diets), Dietary supplements during cancer treatment: interactions and harms, Evidence-based integrative oncology, Misinformation and unproven therapies and the tags complementary, supportive-care.
Shares Unproven diet claims (alkaline, juice, 'anti-cancer' diets), Dietary supplements during cancer treatment: interactions and harms, Evidence-based integrative oncology, Misinformation and unproven therapies and the tags complementary, supportive-care.
Shares Vitamin E supplements, Dietary supplements during cancer treatment: interactions and harms, Evidence-based integrative oncology, Misinformation and unproven therapies and the tags complementary, supportive-care.
Shares Unproven diet claims (alkaline, juice, 'anti-cancer' diets), Dietary supplements during cancer treatment: interactions and harms, Evidence-based integrative oncology, Misinformation and unproven therapies and the tags complementary, supportive-care.
Shares Unproven diet claims (alkaline, juice, 'anti-cancer' diets), Dietary supplements during cancer treatment: interactions and harms, Evidence-based integrative oncology, Misinformation and unproven therapies and the tags complementary, supportive-care.
Shares Unproven diet claims (alkaline, juice, 'anti-cancer' diets), Dietary supplements during cancer treatment: interactions and harms, Evidence-based integrative oncology, Misinformation and unproven therapies and the tags complementary, supportive-care.
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