The relationship between dietary supplements, botanicals and cancer treatment is complex. Some supplements may offer benefits, and others pose risks. While certain compounds show promise in reducing cancer risk or symptoms, no supplement has been proven to cure or prevent cancer. In some cases, supplements can interfere with treatments or even increase cancer risk.
[Read: Where to Go for Cancer Treatment.]
Can Dietary Supplements Cure Cancer?
There is no scientific evidence that any supplement cures cancer.
“Emphatically, supplements do not cure cancer. There is no strong evidence to support that any supplement can cure cancer,” says Nigel Brockton, Vice President of Research at the American Institute for Cancer Research (AICR). He warns that stories claiming supplements have cured a person’s cancer are not evidence that supplements are effective. The Food and Drug Administration (FDA) warns against fraudulent cancer treatment claims often promoted online.
While no single nutrient is a “silver bullet” for cancer, some supplements may support health by boosting immunity or reducing inflammation. However, they should not replace conventional cancer treatments or a balanced diet and lifestyle.
Research is ongoing to evaluate vitamins, minerals and botanicals that may help prevent, treat or reduce cancer symptoms. These answers are not always easy to tease out.
“There are over 55,000 supplements on the market and because there is no standardization, they all vary in composition so the research is extremely challenging,” says RDN Krystal Zuniga, a board-certified specialist in oncology nutrition. “The greatest concern is that supplements can interfere with medical treatments — either decrease the effectiveness of the drugs, cause side effects or affect the metabolism of the drugs.”
High-dose dietary supplements are not recommended for cancer prevention.
“Supplements are designed to fill nutrient gaps, not to treat or prevent cancer,” says Zuniga. This recommendation applies to all doses and formulations of supplements unless they have been advised by a qualified health professional who can assess potential risks and benefits.
[READ: What Is Chemotherapy and How Does It Work?]
What Supplement Is Believed to Cure Cancer?
No supplement or botanical can cure cancer but there are a few that are associated with reducing risk in certain types of cancers. When used properly, certain dietary supplements may help reduce discomfort caused by certain conditions or medicines, or they might help you feel better.
There is evidence that consuming calcium supplements may decrease the risk of?colorectal cancer, but it’s not a cure.
“The only supplement for which there is strong evidence for a beneficial effect is calcium supplements to reduce colorectal cancer,” says Brockton. Calcium can bind substances (bile acids and free fatty acids), which can reduce their toxic effects on the colorectum. “However, these are not recommended to the general public because diets high in calcium may increase prostate cancer risk,” says Brockton.
Overall, experts advise, it’s best to eat a healthy diet rather than rely on dietary supplements to protect against cancer. The World Cancer Research Fund’s Cancer Prevention Recommendations advice is not to use supplements for cancer prevention.
There’s some research evaluating the following supplements, but more research is needed before they can be recommended:
— Omega-3 and Omega-6 fatty acids: Linked to a lower risk of various cancers.
— Vitamin D: Deficiency has been linked to some cancers.
— Curcumin (turmeric extract): Shows potential anti-inflammatory and anti-cancer properties.
— Green tea extract (EGCG): May slow cancer cell growth.
— Medicinal mushrooms: Some mushrooms, like turkey tail, contain beta-glucans that support immune function and may slow tumor growth.
[READ: Surprising Breast Cancer Risk Factors]
Can Supplements Increase Cancer Risk?
Many supplements give you a much higher dose of nutrients than you would normally get from eating food alone. In some cases, these high doses can be harmful.
Supplements can also react with cancer treatment. Several scientific studies have shown that taking supplements reduced how well a treatment worked.
— Beta-carotene: Shown to increase lung cancer risk in smokers.
— Vitamin E and selenium: May increase prostate and skin cancer risks, respectively.
— Collagen supplements: Generally safe, but poor sourcing can lead to contamination with heavy metals.
Can protein supplements cause cancer? Unlikely. Whey and plant-based protein powders are generally safe, but processed protein powders with artificial additives, excessive sugar or heavy metals may have risks.
Additionally, certain ingredients commonly found in supplements, such as artificial colors, hydrogenated oils (also called trans fats) and titanium dioxide (a common ingredient in toothpaste beauty products, and other items), have been linked to health issues ranging from gut inflammation to increased cancer risk.
Some high-dose supplements, such as beta-carotene (an antioxidant the body converts to vitamin A), may increase cancer risk or interfere with treatment.
“Beta-carotene increased the risk of lung cancer in smokers as seen in two clinical supplement trials that had to be stopped early due to finding a higher incidence of the cancer that they were intended to prevent,” says Brockton. Certain supplements can interact with cancer treatments, affecting drug metabolism or effectiveness:
— Antioxidants (vitamins C and E) may reduce the effectiveness of some chemotherapy drugs.
— Vitamin K, turmeric and ginger can interfere with blood thinners, increasing clotting risk.
— St. John’s Wort may reduce the effectiveness of certain cancer medications.
Are Dietary Supplements Safe?
While many supplements are safe when used correctly, they are not regulated like prescription drugs. The FDA can only take action against misleading claims after a product is already on the market.
“Dietary supplements can pose risks, especially for individuals undergoing cancer treatment,” says Zuniga. Side effects from dietary supplements happen most often if people take high doses or use them instead of prescribed medications. Some people believe that mega-doses of certain vitamins can prevent or cure diseases. However, no scientific studies have proven this to be true. Large doses of some vitamins or minerals can be dangerous.
It’s a common belief that natural is safer or better than man-made substances. Not only is this not always true, but some natural products can be harmful — even if used as directed — and present risks. Unknown ingredients, mislabeling and containing little of the active ingredients are just a few of the concerns about supplements.
Despite what a supplement maker claims, dietary supplements or botanicals are not intended to treat, diagnose, cure or relieve the effects of diseases.
If you do use supplements, here are some safety tips to follow when shopping for them:
— Choose supplements from reputable brands with third-party testing (USP, Consumer Labs, NSF).
— Avoid products that claim to cure diseases.
— Be cautious of mislabeled products and unregulated botanical supplements.
[READ: Why Are More Younger People Getting Cancer?]
Choose Whole Foods Over Supplements
A diet rich in whole foods and a measured amount of protein is more effective in reducing cancer risk than supplements.
Cancer puts extra stress on the body demanding additional protein.
“Cancer treatments can kill healthy cells, so in general, we increase protein intake to 1-1.5 grams/kilogram of body weight and even higher with muscle wasting,” says Zuniga.
Whole foods provide essential vitamins, minerals, fiber and antioxidants that work together to support health.
“Many people perceive supplements as a shortcut to compensate for a poor diet. There is also often a feeling of ‘Well, it can’t do any harm.’ Unfortunately, both of these common beliefs are misguided,” says Brockton.
The dietary guidance for cancer prevention is similar to MyPlate and the recommendations from the Dietary Guidelines for Americans. In general, a plant-forward, whole-food diet is recommended:
— Eat plenty of fruits, vegetables, beans, nuts, lean protein, healthy fats and whole grains.
— Limit red meat, alcohol, sugar-sweetened beverages and ultra-processed foods.
— Avoid processed meats.
“The AICR/WCRF Cancer Prevention Recommendations offer the best evidence-based diet for reducing cancer risk and improving outcomes post-diagnosis,” says Brockton.
Bottom Line
“For cancer survivors, during or after treatment, we do not recommend taking supplements,” advises Brockton.
Current research does not support dietary supplements as a primary method to prevent or treat cancer. Conventional treatments — surgery, chemotherapy, radiation and immunotherapy — remain the most effective options. Supplements may provide supportive benefits but should never replace standard care.
Consult a healthcare provider or a registered dietitian specializing in oncology for personalized recommendations. Cancer patients should consult their healthcare provider before taking any supplements.
“Taking a once daily multivitamin that does not exceed the recommended levels of nutrients is perfectly acceptable,” says Zuniga. Personalized medical advice is crucial for safe and effective supplementation.
To learn more about specific supplements, visit the Integrative Medicine Service database at Memorial Sloan Kettering Cancer Center.
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Cancer Supplements: Do They Work? originally appeared on usnews.com
