Natural supplements—the very words sound healthy. Many times, they are. Adding vitamins, minerals and other natural remedies to your daily regimen can boost some people’s immune system, energy level and overall health. But if you’ve been diagnosed with cancer, and especially if you are undergoing treatment, certain supplements may actually harm you. Some may even counteract anti-cancer treatments like chemotherapy. That’s why it is essential that patients always consult with their oncologists before taking any supplements.
It’s an important message many cancer patients don’t appear to hear enough. A 2005 study, published in the journal of the Multinational Association of Supportive Care in Cancer, found that 73 percent of the patients studied had taken herbal supplements within the past 30 days—and 25 percent of chemotherapy patients were taking products suspected of causing adverse reactions when used with chemo. Another big warning sign: The majority of the patients studied, 53 percent, had not consulted their doctors about their supplement use. “Supplements can be useful, when taken under the guidance of a trained health care professional,” says Daniel Kellman, Clinical Director of Naturopathic Medicine at Cancer Treatment Centers of America® (CTCA) in Newnan, Georgia. “But what many people, especially cancer patients, may not know is that some herbal remedies can actually work against them.”
“Many herbal medicines and other nutraceuticals,” Kellman explains, may interfere with how the liver metabolizes chemotherapy drugs. St. John’s wort, a popular plant-based supplement, is one common offender. Used for centuries to combat mild to moderate depression, this plant-based herb is known to increase the production of an enzyme that breaks down certain chemicals and toxins—including many of the agents used in chemotherapy drugs. Other natural supplements that may be detrimental to cancer patients undergoing treatment include:
- Grapefruit or grapefruit juice: A popular diet aid, grapefruit inhibits enzymes in the liver and can interfere with beta blockers.
- Acai berry: Highly touted for health benefits, this palm fruit may interfere with the effectiveness of certain chemotherapy and radiation treatments for the very reason it is celebrated—its antioxidant properties.
- Essiac: An herbal tea mixture that combines burdock root, slippery elm inner bark, sheep sorrel and Indian rhubarb root, it is often touted as an anti-inflammatory agent and pain reliever. But it also affects the liver’s metabolic processes, possibly inhibiting the effectiveness of chemotherapy.
- B17: Often called by the misnomer “vitamin B17,” this is not a vitamin but a supplement from food sources like laetrile, which is found in apricot and apple seeds. Derived from the apricot kernel and touted without proof as a cancer fighter, Kellman says B17 can “have a poisoning effect on the body” because of an inherent chemical ingredient, amygdalin, which turns into cyanide in the stomach.
- Graviola or soursop: A fruit of the graviola tree distinguished by its sweet flesh and flavor, soursop is used to make juice, candy and ice cream. Herbal healers in the Caribbean, Mexico and Central and South America use soursop fruit and graviola leaves to treat stomach ailments, fever, infections and other illnesses, but it has also been linked to unsubstantiated claims that it has anti-cancer properties. Kellman says soursop has not been studied in humans, and when used orally, it may actually be harmful, possibly leading to movement disorders such as Parkinson’s disease and to neurotoxicity when ingested as a tea made from the leaves and stems of the graviola.
- Green tea extract: Popular for its antioxidant effects, green tea is thought to help reduce cholesterol and blood pressure, facilitate weight loss and prevent tooth decay, among other uses. But Kellman says it can also interfere with the drug bortezomid (Velcade), commonly used to treat multiple myeloma.
Kellman also advises cancer patients to ignore commercial advertisements that promote the use of various supplements and vitamins, especially those irresponsibly marketed as cancer treatments, urging patients instead to seek the advice of a naturopathic provider or other health care professional trained in working with cancer patients.
Additional Reading: Find out which natural remedies may help cancer patients safely manage nausea.