Recently, I was asked if it was safe to take nutritional supplements while undergoing cancer treatment? The answer is not so simple. I answered this question with yes and no! The reason I “hedged” is because some supplements might interfere with chemotherapy, while others may help the body defend against tumors.
Some doctors say patients should hold off during chemo, while others say supplements may have cancer-fighting properties and help reduce treatment side effects.
Is it safe to take dietary supplements during active cancer treatment?
For most doctors, this is a gray area. Some doctors tell their patients to hold off, at least while undergoing chemotherapy, but some practitioners in complementary or integrative medicine support the use of certain dietary supplements during active cancer treatments. This is because certain nutritional supplements, such as vitamin D, mushroom extracts, green tea and curcumin, may have cancer-fighting properties and may reduce treatment side effects. What’s important to remember is that if supplements are used, they should be taken along with and not substituted for standard cancer treatment. It’s also safer when patients tell their doctors about supplements they use.
Estimates vary, but studies suggest up to 87 percent of women treated for breast cancer take dietary supplements, indicating that many cancer patients use supplements whether it’s recommended by their doctors or not. Patients being treated for cancer often take supplements without telling their oncologists because often times, the question simply isn’t get asked. And even if it is, the majority of oncologists will tell you not to take supplements during active cancer treatment. One of the reasons is that doctors generally have little to no education about nutrition and supplements during their residency training. Patients may actually know more than their doctors about supplements because of their research. Doctors fear that supplements will interfere with chemotherapy by decreasing the effectiveness of the drugs, causing side effects or affecting the metabolism of the drugs.
A article in Current Oncology Reports (Sept, 2014) listed common dietary supplements and their pros and cons for cancer patients, including the following:
- Curcumin – Contained in the spice turmeric, curcumin has been shown to have cancer-inhibiting action. It is not advised for patients with gallbladder disease, because it may worsen symptoms by stimulating gallbladder contractions.
- Glutamine – glutamine may help relieve chemotherapy side effects such as mouth sores and diarrhea. It also might reduce nerve pain from certain drugs. But, glutamine may interact with medications that are used to prevent seizures.
- Maitake mushrooms – These mushrooms are a staple in Eastern medicine. They have been used to treat high blood pressure and diabetes. There is also evidence that suggests these mushroom extracts may have tumor-fighting properties. Mushroom extracts should not be used for patients on medications to lower blood sugar or those who take the blood-thinning drug warfarin, because of increased risk of bleeding.
- Fish oil – By reducing inflammation, fish oil may potentially slow cancer progression. A study in JAMA Oncology (June, 2014) suggests fish oil may reduce the effectiveness of chemotherapy by possibly by increasing resistance within cancer cells., so patients currently on chemotherapy might do better going off fish oil.
- Probiotics – During chemotherapy, probiotics can help treat diarrhea and other GI side effects.
- Milk thistle – The active part of milk thistle seed, silymarin, may protect the liver from toxic effects of chemotherapy.
- Antioxidant supplements – such as vitamins A, C and E, and beta-carotene – given in high doses, during cancer treatment, may actually hurt patients on chemotherapy.
All cancer patients should have their vitamin D levels tested and if levels are low, they should work with their doctor or dietitian who is familiar with cancer therapies on a supplementation plan to return them to a normal range during treatment. Evidence suggests people with vitamin D deficiency don’t do as well in terms of cancer survival and symptoms. Some cancers can cause a very low level of vitamin D, which can affect immunity and response to therapy. Vitamin D levels above 50 nanograms per milliliter, in the high-normal range, have been shown to reduce the risk of recurrence of breast cancer in survivors.