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Vitamin B12 is essential, and people who lack it, for example after stomach surgery or on long-term metformin or acid-suppressing tablets, need it replaced. Taken as an extra by people who are not deficient it has not been shown to prevent cancer or improve fatigue, and one study linked B12 supplements during chemotherapy with worse outcomes.
Memorial Sloan Kettering's About Herbs entry describes B12 as essential for nerve function, DNA synthesis and blood formation, with deficiency common after gastric surgery, with malabsorption, on proton pump inhibitors, H2 blockers or metformin, on strict vegan diets and in older people; deficiency causes anaemia and neurological problems and is treated with B12. For people who are not deficient the evidence is weaker. Studies of B vitamins for cancer prevention are mixed, and MSK notes that long-term supplementation may increase the risk of lung or colorectal cancer. Preliminary data suggest B12 may reduce aromatase-inhibitor joint and muscle symptoms, but an analysis found that taking B12 or iron supplements during chemotherapy was significantly associated with poorer outcomes, which needs further study. Folic acid above the upper intake limit can mask B12 deficiency. Gastrectomy, some bowel resections and long-term metformin are common in people with cancer, so checking B12 levels and treating a measured deficiency is good care; taking it without a reason is not.
A cofactor for methionine synthase and methylmalonyl-CoA mutase; absorption depends on stomach acid and intrinsic factor, which is why stomach surgery and acid suppression cause deficiency.
Query for this technology: (TITLE:"Vitamin B12 supplements" OR ABSTRACT:"Vitamin B12 supplements" OR TITLE:"Cyanocobalamin" OR ABSTRACT:"Cyanocobalamin" OR TITLE:"Cobalamin" OR ABSTRACT:"Cobalamin") 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 B12 supplements, not a curated reading list.
Shares Aromatase inhibitor, Dietary supplements during cancer treatment: interactions and harms, Evidence-based integrative oncology and the tags complementary, supportive-care.
Shares Dietary supplements during cancer treatment: interactions and harms, Evidence-based integrative oncology, Toxicity and quality of life are undervalued and the tags complementary, supportive-care.
Shares Aromatase inhibitor, Dietary supplements during cancer treatment: interactions and harms, Evidence-based integrative oncology, Toxicity and quality of life are undervalued and the tags complementary, supportive-care.
Shares Dietary supplements during cancer treatment: interactions and harms, Evidence-based integrative oncology, Toxicity and quality of life are undervalued and the tags complementary, supportive-care.
Shares Dietary supplements during cancer treatment: interactions and harms, Evidence-based integrative oncology, Toxicity and quality of life are undervalued and the tags complementary, supportive-care.
Shares Dietary supplements during cancer treatment: interactions and harms, Evidence-based integrative oncology, Toxicity and quality of life are undervalued and the tags complementary, supportive-care.
Shares Aromatase inhibitor, Dietary supplements during cancer treatment: interactions and harms, Evidence-based integrative oncology, Toxicity and quality of life are undervalued and the tags complementary, supportive-care.
Shares Dietary supplements during cancer treatment: interactions and harms, Evidence-based integrative oncology, Toxicity and quality of life are undervalued and the tags complementary, supportive-care.
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