Cancer Treatment: Supplement Warning for Patients
Cancer patients are being urged to disclose all supplement leverage to their oncology teams, as growing evidence suggests certain vitamins and minerals may interfere with treatment efficacy and, in some cases, increase cancer risk. The warning comes as the U.S. Dietary supplement market continues to expand, reaching a value of approximately $63.65 billion in 2024 and projected to exceed $124 billion by 2033, according to industry estimates.
Experts at the Winship Cancer Institute of Emory University emphasize the critical require for open communication between patients and their medical providers regarding supplement use. “9 out of 10” of their patients inquire about supplements, according to integrative oncologist Laura Wright, ND. The concern isn’t necessarily with foundational health practices like obtaining vitamin D through sunlight, but with the often-unregulated composition and potential interactions of commercially available supplements.
While some patients turn to supplements to manage treatment-related symptoms like fatigue, nausea, and constipation, or to bolster their immune systems, research indicates potential harms. Vitamin D is currently a heavily studied supplement in relation to cancer prevention and treatment. However, high doses of antioxidant supplements – including vitamins A, C, E, and beta-carotene – have been linked to increased instances of gastrointestinal cancers, such as stomach, colon, and esophageal cancers, in certain populations, according to recent studies. Conversely, obtaining these vitamins through food sources appears to reduce the risk of various cancers.
Specific supplements also present unique considerations. Folic acid, while helpful in reducing the toxicity of the chemotherapy drug methotrexate, may elevate the risk of prostate cancer in men. Iron supplements can alleviate fatigue caused by anemia resulting from chemotherapy and radiation. Fiber supplements, like psyllium, can aid manage constipation induced by cancer medications.
The Emory Winship Cancer Institute stresses the importance of understanding the contents of supplements and their potential interactions with cancer treatments. The institute’s approach to cancer care prioritizes a team-based strategy focused on the patient’s overall well-being, beginning with foundational health elements. The medical oncology team or a registered dietitian will review a patient’s supplement list, considering existing research and potential conflicts with their treatment plan.
The National Cancer Institute acknowledges that some patients seek dietary supplementation for issues like fatigue and sleep problems, particularly as a response to chemotherapy side effects. However, the agency emphasizes the need for a careful, integrative approach to cancer treatment, where supplements are considered only when conventional treatments are insufficient.