The use of any dietary supplement during the treatment of cancer isn't advisable unless under the direct consent and supervision of a medical professional. Dietary supplements can interact with medications, including chemotherapy drugs. This may make them less effective in treating cancer, potentially affecting your overall prognosis. Always give your doctor a list of the herbs and supplements you're using for your health.
Vitamin B-9, also known as folic acid, can interfere with methotrexate, a chemotherapy drug used in treating cancers of the breast, uterus, lung, head and neck as well as certain types of lymphoma and leukemia, notes the American Cancer Society. Since vitamin B complex often contains this nutrient, its use may compromise the efficacy of methotrexate. It may also adversely interact with other medicines similar to this drug.
Vitamin B-2, more commonly referred to as riboflavin, can deactivate doxorubicin, warns the University of Maryland Medical Center. Like folic acid, riboflavin is typically found in vitamin B complex, so its use could affect the outcome of treatment. Doxorubicin is often used in the treatment for cancers of the breast, ovary, thyroid, stomach, bladder and lung as well as certain types of leukemia and lymphoma. However, doxorubicin is known to deplete riboflavin from the body, so your doctor may recommend its use in certain situations.
Vitamin B-6 may be of benefit during chemotherapy, particularly with 5-fluorouracil and doxorubicin. The University of Maryland Medical Center explains this B vitamin may reduce side effects associated with chemotherapy. Fluorouracil is often used for cancer of the colon, rectum, head and neck.
Like doxorubicin, methotrexate may reduce the level of certain B vitamins in the body, notes the University of Maryland Medical Center. But instead of affecting riboflavin, methotrexate can deplete vitamin B-12 from the body, so your doctor may recommend taking this vitamin during your chemotherapy treatments. This, of course, is different than taking vitamin B complex. Don't self-prescribe any supplement during chemotherapy.