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Submitted by Dr S. Patel on 5 February 2019
Supplement capsules in a spoon in sharp focus against soft focus of vegetables and fruits

Cancer patients often self medicate with vitamins and mineral supplements and other dietary supplements during the course of cancer treatment. Dr. Shital Raval examines the commonly suggested supplements and herbs and the associated risks.

During cancer treatment, eating right is extremely important in order to sustain the side-effects of cancer drugs as well as combat weight loss. Many patients find it difficult to eat, possibly due to loss of appetite, nausea, vomiting, etc. or eat a well-balanced nutritious meal. Hence compensating for the poor diet with vitamins and mineral supplements becomes the self-chosen path for most patients.

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For some patients, supplements are prescribed by their Oncologist for specific deficiencies such as Calcium or Vitamin D for Breast cancer and Prostate cancer patients with weak bones. Many patients also opt to start on herbal supplements or nutritional health pills which are readily sold over the counter. Since herbal and dietary supplements are termed “food” by the FDA in most countries, they are not subjected to testing and labeling standards as prescription drugs. Hence patients need to be aware of the adverse effects of supplements and how it can affect the outcome during cancer treatment.

Adverse Effects of Supplements Can Include:

  • Adverse reactions on skin and soft tissues during radiation
  • Lowering of the efficacy of chemotherapy drugs
  • Counter-interacting with chemotherapy drugs in the liver
  • Affecting the dose of chemo drugs by altering absorption in the digestive tract
  • Causing toxicity
  • Interfering with medications for Diabetes and Cardiovascular comorbidities

The benefits of a few selected supplements such as Vitamin D, green tea, curcumin etc. is greatly encouraged in Integrative and traditional medicine. As research continues to throw more light on which supplements are okay to use, the safest way ahead would be to take precaution and keep your doctor in the loop regarding any or all supplements you are considering while your cancer treatment is underway.

Here is a look at some of the common supplements popularly taken by cancer patients that directly interfere with chemotherapy treatment:

  • Curcumin, also known as turmeric spice is a yellow colored root used vastly in Indian cooking. Curcumin has gained great popularity in recent times as having anti-cancer properties. However, it can disrupt the toxicity balance of chemotherapy drugs and must be avoided during cancer treatment.
  • Fish oils used vastly for decreasing inflammation has found (study in Jama Oncology, June issue) to reduce chemotherapy’s effectiveness by increasing resistance within cancer cells.
  • Valerian root is a plant that seems to aid in helping patients sleep and relieve stress. Many doctors are now discouraging patients from using it as it interferes with chemotherapy drugs.
  • Green tea extract (EGCG) is known for its antioxidant effects and touted as an anti-cancer agent. Taking EGCG is contraindicated in Multiple myeloma patients taking the drug Bortezomid due to its adverse side-effects.
  • Aloe vera juice is a plant with anti-inflammatory properties and claims to balance the immune system and cure cancer. There is currently no evidence to prove that. It can unfortunately also cause diarrhea due to its laxative action and thereby reduce absorption of chemotherapy drugs.
  • CoQ10 is another antioxidant that reduces the free radicals in the body but can also interfere with chemotherapy and must be used under caution.
  • Essiac tea is a herbal mix of some herbal roots and barks, claiming to have pain-relieving action. It has known to interfere with the effectiveness of chemo drugs by affecting the liver, kidney and the colon.
  • St John’s wort is a plant that people often used to treat depression during cancer. However, it can interact and change how certain cancer drugs such as docetaxel, imatinib etc. work.
  • Omega 3 and 6 are essential fatty acids that oxygenate your cells and prevent cancer. A recent study says that fish oil supplements can reduce effectiveness of chemotherapy in mice with cancer.

Here are supplements that interfere with treatment indirectly by instigating adverse side-effects:

  • Echinacea is a herb said to boost immunity and fight cancer. Beware that it can lead to some severe side-effects like constipation, dizziness and liver damage if used for more than 8 weeks.
  • Garlic extract is branded for preventing cancer and detoxifying the liver. However, patients with low blood pressure should avoid taking it.
  • Glutamine is often taken for relief from chemotherapy side-effects such as diarrhea and mucositis but it is contraindicated in patients who take anti-seizure drugs.
  • Medicinal mushrooms like maitake, reishi etc. are traditionally used in Chinese medicine and known for their inflammation and tumour fighting properties. However, patients on diabetic or blood thinning medications should avoid taking them to prevent risk of bleeding.
  • Soy and soy products like tofu, edamame are a great source of protein but experts warn that soy supplements (pills and isoflavone powders) may not be so healthy. In addition, there continues to be confusion on whether phytoestrogens found in soy can increase one’s risk of breast cancer.
  • Vitamin C, D3 and E. Unless there is a real deficiency, excess levels of vitamins can cause toxicity and increase risk of complications. Evidence on whether anti-oxidants are helpful to cancer patients is uncertain.
  • Melatonin is an enzyme naturally produced by the brain to induce sleep at night. It is used to reduce unwanted symptoms from cancer treatment but can also cause several side-effects if used long term.
  • Artemisinin or Wormwood is a plant that can supposedly disable cancer cells, but has reported to cause liver problems in patients who have taken high doses of it.
  • B17 or commonly misnamed as Vitamin B17 is actually a supplement and not a vitamin at all. Peddled as the latest cancer cure via fake whatsapp messages, it can in fact have a poisonous effect on the body due to its ability to make cyanide inside the stomach.

In general, it is best to procure nutrients from foods instead of supplements. Consuming a well-balanced, plant-based diet is recommended for cancer patients during treatment. Supplement may be prescribed by your doctor in cases of deficiencies found in your blood reports.

Patients must ask their doctor before they plan to take any supplements on their own during the course of treatment.

After the course of the cancer treatment has been completed, survivors are free to take supplements of their choice.

References:

  1. Vitamins and diet supplements. https://www.cancerresearchuk.org/about-cancer/cancer-in-general/treatment/complementary-alternative-therapies/individual-therapies/vitamins-diet-supplements
  2. Natural supplements for cancer patients: 7 to avoid. December 2015. https://www.cancercenter.com/discussions/blog/natural-supplements-for-cancer-patients-7-to-avoid/
  3. Supplements to avoid during chemotherapy. May 2018. https://health.ucsd.edu/news/features/pages/2018-05-11-otc-supplements-to-avoid-during-chemotherapy.aspx
  4. Food and drink to avoid during cancer treatment https://www.cancerresearchuk.org/about-cancer/cancer-in-general/treatment/cancer-drugs/how-you-have/taking-medicines/foods-drinks-avoid
  5. Soy and Breast Cancer. https://www.oncologynutrition.org/erfc/hot-topics/soy-and-breast-cancer/
  6. 31 powerful herbs and supplements for treating and preventing cancer naturally. https://www.consciouslifestylemag.com/supplements-and-herbs-for-cancer-fighting/
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