What are supplements?

Simply put, supplements are anything you take to boost your body’s level of vitamins, minerals, hormones, or other nutrients.

You might hear them called dietary supplements because they are intended to supplement, or add to, the nutrients you get from food and drink. ³

Supplements come in many forms, including tablets, capsules, gummies, liquids (including teas), and powders.

Supplements are very popular. One study showed that more than 80 percent of adults in the United States take supplements. But only 24 percent take them because tests showed they were lacking in a certain vitamin, mineral, or other nutrient. ⁵ In other words, many people are taking supplements they may not need.

Are supplements harmless?

“What can it hurt?” you might think. After all, getting the vitamins, minerals, and other nutrients you need must be especially important when you have cancer. However, there are important reasons to talk with your cancer care team about supplements.

• Supplements vary in quality. Some are made in clean, controlled laboratories, and others are not. In the United States, supplements are not regulated for safety or effectiveness before they go to market. ²
• Labels may not be accurate. Some supplements have clear, accurate labels. Others do not. Your supplement may contain substances that are not listed on the label. “You have to be wary about the quality of any products you get,” says Dr. White. “The bottle may say it contains the product you’re interested in, but you really have no idea what is in that bottle.” The herbal supplement PC-SPES, used by many patients with prostate cancer, was taken off the market after being found to contain the drugs DES, warfarin, indomethacin, and alprazolam, none of which were listed on the label. ⁴
• The same supplement may go by several different names. ³ This can be confusing and even lead to overdosing.
• Supplements can interact with medications and treatments. Substances in your supplement can interact with your regular medications or cancer treatments, making them less effective or even toxic.
• You may not need everything in the supplement. Even if everything is listed on the label, the supplement may contain substances you don’t need or that are harmful based on your age, sex, or other health conditions.
• Supplements can interact with medications and treatments. Substances in your supplement can interact with your regular medications or cancer treatments, making them less effective or even toxic.
• Your body might not be able to absorb the active ingredient. For example, curcumin is beneficial but very little enters enter your bloodstream unless it is combined with dietary fats or a compound found in black pepper. ⁶

How to talk with your health-care provider

“It’s incredibly important to stay honest and open about what you’re interested in, taking now, or want to try,” says Dr. White. “A lot of people are concerned about expressing things to their doctor. Some physicians are not as open to discussion as others, so this can be challenging, but I always recommend keeping the information exchange open on both sides.”

Ways to bring up supplements with your provider include asking:

• Will taking a supplement interfere with any of my current medications or treatments?
• Will my cancer or treatment lower my level of any necessary nutrients?
• Would taking a supplement help me stay healthier during treatment?
• Would taking a supplement boost my immune system? Is that a good idea right now?

If you already take supplements

A Harris poll of more than 2,000 U.S. adults found that more than one-third “didn’t think their health care provider was interested” in whether they took supplements or not. ¹ In fact, they are. To start the conversation, you might share something like I take ________________ and ___________________ for my health (e.g., calcium for bone health and vitamins for my eyesight). I also drink __________________________ tea (e.g., echinacea)

Supplements for specific symptoms

Enough scientific evidence exists for some dietary supplements to recommend taking them for specific symptoms and side effects, provided there are not specific reasons you should not be taking them.

Talk with your oncologist or other health-care provider before trying any of these. They may recommend a specific dose or formula.

*Please note that many of the comments in this column are not derived from results of clinical trials. Consult your doctor if you are taking any of these or other supplements.

Supplements and your treatment plan

Supplements contain powerful substances, including harmful ones. They also come in and out of vogue, often touted online by non-medical websites.

“Vitamin C is something many people are interested in and consume,” says Dr. White. “Nowadays, it seems to be mostly high dose IV vitamin C as opposed to pills. That’s not really a dietary supplement—that is more like a drug.”

“Social media has a big impact,” Dr. Abrams says. “Someone goes online and says, ‘This cured my cancer.’ Even laetrile, which was debunked in the 1960s, is back as ‘apricot pits’ or ‘vitamin B17.’”

How supplements can affect you

Some supplements can make your skin more sensitive. This can lead to severe skin reactions during radiation therapy.

• Some herbs make chemotherapy drugs less effective, like St. John’s wort, listed in the box. They can also cause side effects such as bleeding.
• Some herbs and natural compounds, including ginkgo and grapefruit, block the liver enzymes that break down chemotherapy drugs. This can lead to toxic effects.
• Taking antioxidants may make some chemotherapy drugs less effective. “Antioxidants fight free radicals, but the point of radiation and some chemotherapy is to create free radicals to kill cancer cells,” says Dr. Abrams.

“Foods with antioxidant properties are fine,” Dr. Abrams says. “People ask me, ‘Can I eat blueberries? They contain antioxidants.’ The answer is yes, because blueberries do not contain such large amounts that they will interfere with chemotherapy, and they contain many other health-building compounds.”

Can supplements cure cancer?

Are supplements effective at destroying cancer cells or shrinking tumors? Not that we know, according to Dr. Abrams. “For the most part, that idea is more wishful thinking than based in evidence. With many supplements, we simply do not have a body of evidence from placebo-controlled trials.”

Dr. White offers this advice: “If you hear that a supplement kills cancer cells, ask, ‘Did this happen in a petri dish? Did it happen in laboratory animals? Where are the studies showing that it works in humans?”

“I see many patients extrapolating from what happens in test tubes and animals to what happens in their bodies, particularly if they hope that supplements will cure their cancer,” says Dr. Abrams. “But the human body is more complex than cells in a laboratory dish.”

How to evaluate supplements

When considering any supplement, Dr. White says, “First ask, ‘What is the scientific evidence?’ If it is all anecdotal—personal stories—you don’t have much.”

Ask your oncologist if studies have shown the supplement or product is effective for your concern. Nurses and pharmacists can also help you find reliable information.

Questions to ask

• Do I take medications that lower the level of nutrients in my body? Do I need supplements to replace these nutrients?
• Does everyone on my cancer team know what supplements I take? Will my supplements affect my cancer treatment?
• Do my supplements contain high-quality ingredients? Are there any dangerous ingredients?
• Do high-quality research studies show this supplement works for my concern? Or, does an experienced health-care provider recommend it?
• Will the supplement affect other health conditions besides my cancer? How?
• Is a different medication or approach safer or more effective?

Resources

• Look for products with the NSF International, USP, or Consumer Laboratories seal.
• Check the U.S. Pharmacopoeia information on dietary supplements and food at https://qualitymatters.usp.org/topics/dietary-supplements.
• See the Dietary and Herbal Supplements guide at the National Center for Complementary and Integrative Health.
• Subscribe to ConsumerLab.com for reviews of supplements and other health products.
• Check the FDA Dietary Supplement Ingredient Advisory List, and sign up to get alerts when new ingredients are added.
• Check the FDA’s What’s New in Dietary Supplements page for the latest news and actions.
• Your Healing Journey: A Patient’s Guide to Integrative Breast Cancer Care Guide (PDF)
• Chemotherapy-Induced Peripheral Neuropathy (CIPN) Pocket Guide
• Physician Data Query (PDQ®), National Cancer Institute
• About Herbs (MSKCC)
• Natural Medicines database
• Search Wellkasa to find science on supplements and information on drug-supplement interaction.

References

1. DrWayneJonas.com. The state of supplements. [Infographic.] Available at https://healingworksfoundation.org/resource/the-state-of-supplements-inforgaphic/. Accessed November 10, 2021.
2. US Food and Drug Administration. What you need to know about dietary supplements. Available at https://www.fda.gov/food/buy-store-serve-safe-food/what-you-need-know-about-dietary-supplements. Accessed November 10, 2021.
3. American Institute for Cancer Research, LIVESTRONG Foundation, and Savor Health. Heal Well: A Cancer Nutrition Guide. December 2015. Available at Meals-to-Heal-Heal-Well-Nutrition-Guide.pdf Accessed November 9, 2021.
4. White J. PC-SPES: A lesson for future dietary supplement research. J Nat Cancer Inst 2002;94(17):1261-1263.
5. American Osteopathic Association. Poll finds 86% of Americans take vitamins or supplements yet only 24% have a confirmed nutritional deficiency. Available at https://thedo.osteopathic.org/2019/01/most-americans-take-vitamins-and-supplements-without-tests-indicating-deficiencies/. Accessed November 11, 2021.
6. Anand P, Kunnumakkara AB, Newman RA, Aggarwal BB. Bioavailability of curcumin: problems and promises. Mol Pharm 2007;4(6):807-818. doi:10.1021/mp700113r