Thinking about supplements during cancer treatment? Read this first

Article written in collaboration with Stacy D. D'Andre, M.D.

During cancer treatment, individuals often look for additional ways to support their health, including the use of nutritional supplements. There are many tools that support good health, and some—such as physical activity, adequate sleep, social connection, and healthy nutrition—are well documented. Information about the benefits of nutritional supplements is more varied. We are frequently exposed to health advice from friends, family, social media, and the internet. While some of this information is accurate and evidence-based, much of it is not. Medical misinformation is often shared based on personal stories, anecdotes, or questionable evidence, and may sound convincing despite lacking scientific support. In some cases, this misinformation includes recommendations for supplements or other substances that are not only ineffective, but potentially harmful.

One area with significant conflicting information is the role of dietary supplements. Because healthy nutrition provides a wide range of nutrients that help restore strength, rebuild tissue, and support overall well-being, it may seem logical that taking these nutrients in high doses as supplements would provide additional benefits. However, in most cases, the best approach is to work with your healthcare team to optimize your nutrition through food sources rather than supplements.

Taking nutritional supplements—especially high-dose vitamins and minerals—may actually be harmful. Some dietary supplements can increase the risk of bleeding, which is particularly dangerous if you are having surgery. Others may interact with prescription medications. Certain supplements, including high-dose vitamins and minerals, can interfere with cancer treatments such as chemotherapy or radiation therapy. Some supplements use the same pathways into cells as chemotherapy drugs, which may reduce the effectiveness of treatment or increase side effects to toxic levels. Antioxidant supplements may protect both healthy and cancer cells, potentially decreasing the effectiveness of chemotherapy or radiation therapy. While antioxidant-rich foods typically do not interfere with cancer treatments, supplements often contain much higher doses and may cause problems.

That said, if you have a diagnosed vitamin or mineral deficiency, supplementation may be appropriate. Your healthcare provider can check laboratory values to determine your specific needs and prescribe supplements that are safe and unlikely to interfere with chemotherapy or radiation therapy.

Be sure to discuss all medications, supplements, vitamins, minerals, and other substances you are taking with your healthcare provider. Many cancer centers have registered dietitians and other specialists who can provide accurate, evidence-based guidance on nutrition and supplement use.

Learn more:

Mayo Clinic Minute Video: Are supplements safe for cancer patients?

National Cancer Institute: Complementary and Alternative Medicine

Herbs at a Glance | NCCIH

Meet others talking about managing cancer in the Mayo Clinic Connect Cancer: Managing Symptoms support group online forum.

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