Cancer Therapy Interactions With Foods and Dietary Supplements (PDQ®): Integrative, alternative, and complementary therapies - Patient Information [NCI]

Cancer Therapy Interactions With Foods and Dietary Supplements (PDQ®): Integrative, alternative, and complementary therapies - Patient Information [NCI]

This information is produced and provided by the National Cancer Institute (NCI). The information in this topic may have changed since it was written. For the most current information, contact the National Cancer Institute via the Internet web site at http://cancer.gov or call 1-800-4-CANCER.

General Information

Over one-third of adults with cancer in the United States use some form of complementary and alternative medicine (CAM). CAM medical products may include dietary supplements, herbal products, and special teas. Taking anticancer drugs and CAM together may cause adverse outcomes.

When dietary supplements, herbs, or other forms of CAM are taken with an anticancer drug, there is a risk they will change the way the cancer drug works. They may change how the cancer drugs are absorbed, distributed in the body, and excreted, causing effects that are not expected.

Specific enzymes and factors help drugs work in the body. The cytochrome P450 superfamily of enzymes play a major role in the metabolism of many cancer drugs. The transport protein, P-glycoprotein, is another factor involved in how cancer drugs work in the body. If a dietary supplement impacts a cytochrome P450 enzyme or P-glycoprotein, the cancer drug will not work like it should and the patient will not receive the full benefits of the drug.

Research on dietary supplements and cancer drugs is limited, but there is evidence for adverse effects and reactions. This summary covers some of those possible effects between foods or dietary supplements and cancer drugs.

Antioxidants

Questions and Answers About Antioxidants

What are antioxidants?

Antioxidants are natural or man-made substances found in foods and dietary supplements that protect cells from the damage caused by free radicals (unstable molecules made by oxidation during normal metabolism). Free radicals may play a part in cancer, heart disease, stroke, and other diseases of aging.

Some common dietary antioxidants include the following:

  • Vitamin C (ascorbate).
  • Vitamin E.
  • Flavonoids (such as soy isoflavones, green tea catechins).
  • Beta-carotene.
  • Glutathione.
How are antioxidants given or taken?

Antioxidants found in fruits, vegetables, and dietary supplements are taken by mouth.

Have any laboratory or animal studies been done on antioxidants and drug interactions?

See the Laboratory/Animal/Preclinical Studies section of the health professional version of Cancer Therapy Interactions With Foods and Dietary Supplements for information on laboratory and animal studies done using antioxidants.

Have any studies been done on antioxidants and drug interactions in people with cancer?

One study looked at antioxidant dietary supplement use before and after diagnosis in postmenopausal breast cancer survivors. This study found an increased risk of death and a reduced chance of staying cancer free when antioxidant dietary supplements were used during chemotherapy and radiation therapy. Another study found similar results for people with breast cancer who used antioxidant dietary supplements before and during chemotherapy.

Clinical trials of people with head and neck cancer who took vitamin E supplements looked at a compound in the supplements known as alpha-tocopherol. Researchers studied alpha-tocopherol to see if it decreased adverse effects from chemotherapy and radiation therapy. Although some clinical trials reported that alpha-tocopherol may reduce damage to the body caused by radiation therapy, other clinical trials found there was a higher risk of cancer coming back.

Have any side effects or risks been reported from antioxidants?

Antioxidant dietary supplements that are taken while being treated with chemotherapy or radiation therapy may reduce the chance of staying cancer free. Some patients take antioxidants because they think the supplement will protect and repair healthy cells damaged by cancer drugs. There is not enough evidence on antioxidant supplements to know if they are safe and effective as a complementary therapy when taken with standard cancer treatment.

Are antioxidants approved by the U.S. Food and Drug Administration (FDA) for use as a cancer treatment in the United States?

FDA has not approved the use of antioxidants as a treatment for cancer or any other medical condition.

Antioxidants are available in the United States in food products and dietary supplements. FDA does not approve dietary supplements as safe or effective. The company that makes the dietary supplements is responsible for making sure that they are safe and that the claims on the label are true and do not mislead the consumer. The way that supplements are made is not regulated by FDA, so all batches and brands of antioxidant supplements may not be the same.

Herbs

Questions and Answers About Ginseng

What is ginseng?

Ginseng is a root that has been used as a dietary supplement in traditional Asian medicine. People take ginseng for the following health benefits:

  • To improve one's focus and quality of life.
  • To build up the immune system.
  • To help with health problems such as heart disease, depression, and anxiety.
How is ginseng given or taken?

Ginseng is a dietary supplement that is taken by mouth.

Have any laboratory or animal studies been done on ginseng and drug interactions?

See the Laboratory/Animal/Preclinical Studies section of the health professional version of Cancer Therapy Interactions With Foods and Dietary Supplements for information on laboratory and animal studies done using ginseng.

Have any studies been done on ginseng and drug interactions in people with cancer?

A case study found that a young man who was treated with an anticancer drug took ginseng as part of an energy drink was diagnosed with liver damage. More research is needed to find out if the ginseng or something else in the energy drink caused the liver damage.

Have any side effects or risks been reported from ginseng?

The most common side effect is poor sleep. Other side effects from taking ginseng supplements include the following:

  • Menstrual problems.
  • Breast pain.
  • Fast heart rate.
  • High or low blood pressure.
  • Headache.
  • Loss of appetite.
  • Digestive problems.
Is ginseng approved by the U.S. Food and Drug Administration (FDA) for use as a cancer treatment in the United States?

FDA has not approved the use of ginseng as a treatment for cancer or any other medical condition.

Ginseng is available in the United States as a dietary supplement. FDA does not approve dietary supplements as safe or effective. The company that makes the dietary supplements is responsible for making sure that they are safe and that the claims on the label are true and do not mislead the consumer. The way that supplements are made is not regulated by FDA, so all batches and brands of ginseng supplements may not be the same.

Questions and Answers About Scutellaria baicalensis/Wogonin

What is Scutellaria baicalensis?

Scutellaria biacalensis is a plant used in traditional Chinese medicine to treat medical conditions such as diarrhea, hepatitis, infections, and inflammation. Scutellaria biacalensis is also known as wogonin, Chinese skullcap, or Huang Qin.

How is Scutellaria biacalensis given or taken?

Scutellaria biacalensis is a dietary supplement that is taken by mouth.

Have any laboratory or animal studies been done on Scutellaria biacalensis and drug interactions?

See the Laboratory/Animal/Preclinical Studies section of the health professional version of Cancer Therapy Interactions With Foods and Dietary Supplements for information on laboratory and animal studies done using Scutellaria biacalensis.

Have any studies been done on Scutellaria biacalensis and drug interactions in people with cancer?

No clinical trials or other studies in people with cancer have been published in peer-reviewed scientific journals to support the safety or effectiveness of Scutellaria biacalensis.

Have any side effects or risks been reported from Scutellaria baicalensis?

Information about side effects or risks from taking Scutellaria baicalensis is not available because there have been no clinical trials or other studies done in people with cancer. Some research has shown that Scutellaria biacalensis may change the anticancer effects of certain drugs.

Is Scutellaria biacalensis approved by the U.S. Food and Drug Administration (FDA) for use as a cancer treatment in the United States?

FDA has not approved the use of Scutellaria biacalensis as a treatment for cancer or any other medical condition.

Scutellaria biacalensis is available in the United States as a dietary supplement. FDA does not approve dietary supplements as safe or effective. The company that makes the dietary supplements is responsible for making sure that they are safe and that the claims on the label are true and do not mislead the consumer. The way that supplements are made is not regulated by FDA, so all batches and brands of Scutellaria biacalensis supplements may not be the same.

Questions and Answers About St. John's Wort

What is St. John's wort?

St. John's wort (Hypericum perforatum) is a flowering plant that has been used to help with sleep issues, lung and kidney problems, and wound healing. Today, it is often used for depression.

How is St. John's wort given or taken?

St. John's wort is a dietary supplement. The flowers from the St. John's wort plant can be taken in the form of tablets, teas, capsules, or extracts.

Have any laboratory or animal studies been done on St. John's wort and drug interactions?

See the Laboratory/Animal/Preclinical Studies section of the health professional version of Cancer Therapy Interactions With Foods and Dietary Supplements for information on laboratory and animal studies done using St. John's wort.

Have any studies been done on St. John's wort and drug interactions in people with cancer?

Studies have found that patients who took St. John's wort while receiving anticancer drugs had lower levels of the drugs in their blood. Anticancer drugs may be less effective if taken with St. John's wort.

Have any side effects or risks been reported from St. John's wort?

St. John's wort can interact with how other medicines are absorbed in the body. These interactions can cause side effects, including the following:

  • Sensitivity to sunlight.
  • Trouble sleeping.
  • Anxiety.
  • Dry mouth.
  • Dizziness.
  • Digestive problems.
  • Fatigue.
  • Headache.
  • Problems with sexual function.

St. John's wort can interact with medicines for depression causing unsafe levels of serotonin, a chemical substance found in the brain. When serotonin increases to a certain level, it can be dangerous.

Is St. John's wort approved by the U.S. Food and Drug Administration (FDA) for use as a cancer treatment in the United States?

FDA has not approved the use of St. John's wort as a treatment for cancer or any other medical condition.

St. John's wort is available in the United States as a dietary supplement. FDA does not approve dietary supplements as safe or effective. The company that makes the dietary supplements is responsible for making sure that they are safe and that the claims on the label are true and do not mislead the consumer. The way that supplements are made is not regulated by FDA, so all batches and brands of St. John's wort supplements may not be the same.

Questions and Answers About Thunder God Vine

What is thunder god vine?

Thunder god vine, also known as Tripterygium wilfordii Hook F, is an herb used in traditional Chinese medicine to help with inflammation and lessen immune responses. Two ingredients in thunder god vine—triptolide and celastrol—are being studied for anticancer effects.

How is thunder god vine given or taken?

Thunder god vine is a dietary supplement that can be taken by mouth. It can also be applied to the skin.

Have any laboratory or animal studies been done on thunder god vine and drug interactions?

See the Laboratory/Animal/Preclinical Studies section of the health professional version of Cancer Therapy Interactions With Foods and Dietary Supplements for information on laboratory and animal studies done using thunder god vine.

Have any studies been done on thunder god vine and drug interactions in people with cancer?

No clinical trials or other studies in people with cancer have been published in peer-reviewed scientific journals to support the safety or effectiveness of thunder god vine.

Have any side effects or risks been reported from thunder god vine?

Thunder god vine can cause many side effects, including the following:

  • Digestive problems.
  • Abnormal heart rate.
  • High blood pressure.
  • Low blood count.
  • Kidney problems.
  • Low bone density.
  • Infertility.
  • Menstrual cycle changes.
  • Rash.
  • Diarrhea.
  • Headache.
  • Hair loss.
Is thunder god vine approved by the U.S. Food and Drug Administration (FDA) for use as a cancer treatment in the United States?

FDA has not approved the use of thunder god vine as a treatment for cancer or any other medical condition.

Thunder god vine is available in the United States as a dietary supplement. FDA does not approve dietary supplements as safe or effective. The company that makes the dietary supplements is responsible for making sure that they are safe and that the claims on the label are true and do not mislead the consumer. The way that supplements are made is not regulated by FDA, so all batches and brands of thunder god vine supplements may not be the same.

Foods

Questions and Answers About Grapefruit

What is grapefruit?

Grapefruit is a fruit in the citrus family. Grapefruit and fruits similar to grapefruit, such as Seville oranges, pomelos, and limes, are known to interact with anticancer drugs. The seeds from the fruit contain furanocoumarin that may cause adverse effects.

How is grapefruit given or taken?

People eat grapefruit or take it as a dietary supplement (in the form of an extract made from the seeds). Some people drink grapefruit juice.

Have any laboratory or animal studies been done on grapefruit and drug interactions?

See the Laboratory/Animal/Preclinical Studies section of the health professional version of Cancer Therapy Interactions With Foods and Dietary Supplements for information on laboratory and animal studies done using grapefruit.

Have any studies been done on grapefruit and drug interactions in people with cancer?

A small randomized trial found that less of the anticancer drug etoposide reached the bloodstream in people who drank grapefruit juice than it did in people who did not drink grapefruit juice. However, studies with the anticancer drugs imatinib, sunitinib, and nilotinib have shown that drinking grapefruit juice increased the amount of anticancer drug that reached the bloodstream.

Have any side effects or risks been reported from grapefruit?

Grapefruit can interact with many medicines used to treat a variety of health problems. Grapefruit juice and the furanocoumarin in grapefruit seeds have been known to interact with some anticancer drugs.

Is grapefruit approved by the U.S. Food and Drug Administration (FDA) for use as a cancer treatment in the United States?

FDA has not approved the use of grapefruit as a treatment for cancer or any other medical condition.

Grapefruit is available in the United States in food products or as a dietary supplement. FDA does not approve dietary supplements as safe or effective. The company that makes the dietary supplements is responsible for making sure that they are safe and that the claims on the label are true and do not mislead the consumer. The way that supplements are made is not regulated by FDA, so all batches and brands of grapefruit seed extracts may not be the same.

Questions and Answers About Green Tea

What is green tea?

Green tea comes from the Camellia sinensis plant. Green tea has been used to lower cholesterol and improve weight loss, mental alertness, and digestive symptoms.

The health benefits studied in green tea are thought to be from compounds called polyphenols. Polyphenols are a group of plant chemicals that include catechins (antioxidants that help protect cells from damage). Catechins make up most of the polyphenols in green tea.

How is green tea given or taken?

People usually drink green tea or take it as a dietary supplement in the form of a dried herb or an extract.

Have any laboratory or animal studies been done on green tea and drug interactions?

See the Laboratory/Animal/Preclinical Studies section of the health professional version of Cancer Therapy Interactions With Foods and Dietary Supplements for information on laboratory and animal studies done using green tea.

Have any studies been done on green tea and drug interactions in people with cancer?

Clinical research with people is limited. A case study of a patient with metastatic renal cell carcinoma who drank green tea while he received an anticancer drug reported worse symptom control. The symptoms improved when he stopped drinking the green tea.

Have any side effects or risks been reported from green tea?

Risks and side effects result from drinking large amounts of green tea (more than 8 cups per day). In rare cases, green tea extracts taken in pill form have caused damage to the liver. Green tea may interact with other medicines. Studies have not determined whether green tea is safe or effective when used with anticancer drugs.

Is green tea approved by the U.S. Food and Drug Administration (FDA) for use as a cancer treatment in the United States?

FDA has not approved the use of green tea as a treatment for cancer.

The FDA Division of Drug Oncology Products recommends that green tea extract be taken with food by participants in clinical trials and that liver function tests be considered during treatment.

Green tea is available in the United States in food products and dietary supplements. FDA does not approve dietary supplements as safe or effective. The company that makes the dietary supplements is responsible for making sure that they are safe and that the claims on the label are true and do not mislead the consumer. The way that supplements are made is not regulated by FDA, so all batches and brands of green tea supplements may not be the same.

About This PDQ Summary

About PDQ

Physician Data Query (PDQ) is the National Cancer Institute's (NCI's) comprehensive cancer information database. The PDQ database contains summaries of the latest published information on cancer prevention, detection, genetics, treatment, supportive care, and complementary and alternative medicine. Most summaries come in two versions. The health professional versions have detailed information written in technical language. The patient versions are written in easy-to-understand, nontechnical language. Both versions have cancer information that is accurate and up to date and most versions are also available in Spanish.

PDQ is a service of the NCI. The NCI is part of the National Institutes of Health (NIH). NIH is the federal government's center of biomedical research. The PDQ summaries are based on an independent review of the medical literature. They are not policy statements of the NCI or the NIH.

Purpose of This Summary

This PDQ cancer information summary has current information about cancer therapy interactions with foods and dietary supplements in people with cancer. It is meant to inform and help patients, families, and caregivers. It does not give formal guidelines or recommendations for making decisions about health care.

Reviewers and Updates

Editorial Boards write the PDQ cancer information summaries and keep them up to date. These Boards are made up of experts in cancer treatment and other specialties related to cancer. The summaries are reviewed regularly and changes are made when there is new information. The date on each summary ("Updated") is the date of the most recent change.

The information in this patient summary was taken from the health professional version, which is reviewed regularly and updated as needed, by the PDQ Integrative, Alternative, and Complementary Therapies Editorial Board.

Clinical Trial Information

A clinical trial is a study to answer a scientific question, such as whether one treatment is better than another. Trials are based on past studies and what has been learned in the laboratory. Each trial answers certain scientific questions in order to find new and better ways to help cancer patients. During treatment clinical trials, information is collected about the effects of a new treatment and how well it works. If a clinical trial shows that a new treatment is better than one currently being used, the new treatment may become "standard." Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.

Clinical trials can be found online at NCI's website. For more information, call the Cancer Information Service (CIS), NCI's contact center, at 1-800-4-CANCER (1-800-422-6237).

Permission to Use This Summary

PDQ is a registered trademark. The content of PDQ documents can be used freely as text. It cannot be identified as an NCI PDQ cancer information summary unless the whole summary is shown and it is updated regularly. However, a user would be allowed to write a sentence such as "NCI's PDQ cancer information summary about breast cancer prevention states the risks in the following way: [include excerpt from the summary]."

The best way to cite this PDQ summary is:

PDQ® Integrative, Alternative, and Complementary Therapies Editorial Board. PDQ Cancer Therapy Interactions With Foods and Dietary Supplements. Bethesda, MD: National Cancer Institute. Updated <MM/DD/YYYY>. Available at: https://www.cancer.gov/about-cancer/treatment/cam/patient/dietary-interactions-pdq. Accessed <MM/DD/YYYY>.

Images in this summary are used with permission of the author(s), artist, and/or publisher for use in the PDQ summaries only. If you want to use an image from a PDQ summary and you are not using the whole summary, you must get permission from the owner. It cannot be given by the National Cancer Institute. Information about using the images in this summary, along with many other images related to cancer can be found in Visuals Online. Visuals Online is a collection of more than 3,000 scientific images.

Disclaimer

The information in these summaries should not be used to make decisions about insurance reimbursement. More information on insurance coverage is available on Cancer.gov on the Managing Cancer Care page.

Contact Us

More information about contacting us or receiving help with the Cancer.gov website can be found on our Contact Us for Help page. Questions can also be submitted to Cancer.gov through the website's E-mail Us.

General CAM Information

Complementary and alternative medicine (CAM)—also called integrative medicine—includes a broad range of healing philosophies, approaches, and therapies. A therapy is generally called complementary when it is used in addition to conventional treatments; it is often called alternative when it is used instead of conventional treatment. (Conventional treatments are those that are widely accepted and practiced by the mainstream medical community.) Depending on how they are used, some therapies can be considered either complementary or alternative. Complementary and alternative therapies are used in an effort to prevent illness, reduce stress, prevent or reduce side effects and symptoms, or control or cure disease.

Unlike conventional treatments for cancer, complementary and alternative therapies are often not covered by insurance companies. Patients should check with their insurance provider to find out about coverage for complementary and alternative therapies.

Cancer patients considering complementary and alternative therapies should discuss this decision with their doctor, nurse, or pharmacist as they would any type of treatment. Some complementary and alternative therapies may affect their standard treatment or may be harmful when used with conventional treatment.

Evaluation of CAM Therapies

It is important that the same scientific methods used to test conventional therapies are used to test CAM therapies. The National Cancer Institute and the National Center for Complementary and Integrative Health (NCCIH) are sponsoring a number of clinical trials (research studies) at medical centers to test CAM therapies for use in cancer.

Conventional approaches to cancer treatment have generally been studied for safety and effectiveness through a scientific process that includes clinical trials with large numbers of patients. Less is known about the safety and effectiveness of complementary and alternative methods. Few CAM therapies have been tested using demanding scientific methods. A small number of CAM therapies that were thought to be purely alternative approaches are now being used in cancer treatment—not as cures, but as complementary therapies that may help patients feel better and recover faster. One example is acupuncture. According to a panel of experts at a National Institutes of Health (NIH) meeting in November 1997, acupuncture has been found to help control nausea and vomiting caused by chemotherapy and pain related to surgery. However, some approaches, such as the use of laetrile, have been studied and found not to work and to possibly cause harm.

The NCI Best Case Series Program which was started in 1991, is one way CAM approaches that are being used in practice are being studied. The program is overseen by the NCI's Office of Cancer Complementary and Alternative Medicine (OCCAM). Health care professionals who offer alternative cancer therapies submit their patients' medical records and related materials to OCCAM. OCCAM carefully reviews these materials to see if any seem worth further research.

Questions to Ask Your Health Care Provider About CAM

When considering complementary and alternative therapies, patients should ask their health care provider the following questions:

  • What side effects can be expected?
  • What are the risks related to this therapy?
  • What benefits can be expected from this therapy?
  • Do the known benefits outweigh the risks?
  • Will the therapy affect conventional treatment?
  • Is this therapy part of a clinical trial?
  • If so, who is the sponsor of the trial?
  • Will the therapy be covered by health insurance?

To Learn More About CAM

National Center for Complementary and Integrative Health (NCCIH)

The National Center for Complementary and Integrative Health (NCCIH) at the National Institutes of Health (NIH) facilitates research and evaluation of complementary and alternative practices, and provides information about a variety of approaches to health professionals and the public.

NCCIH Clearinghouse
Post Office Box 7923 Gaithersburg, MD 20898–7923
Telephone: 1-888-644-6226 (toll free)
TTY (for deaf and hard of hearing callers): 1-866-464-3615
E-mail: info@nccih.nih.gov
Website: https://nccih.nih.gov

CAM on PubMed

NCCIH and the NIH National Library of Medicine (NLM) jointly developed CAM on PubMed, a free and easy-to-use search tool for finding CAM-related journal citations. As a subset of the NLM's PubMed bibliographic database, CAM on PubMed features more than 230,000 references and abstracts for CAM-related articles from scientific journals. This database also provides links to the websites of over 1,800 journals, allowing users to view full-text articles. (A subscription or other fee may be required to access full-text articles.)

Office of Cancer Complementary and Alternative Medicine

The NCI Office of Cancer Complementary and Alternative Medicine (OCCAM) coordinates the activities of the NCI in the area of complementary and alternative medicine (CAM). OCCAM supports CAM cancer research and provides information about cancer-related CAM to health providers and the general public via the NCI website.

National Cancer Institute (NCI) Cancer Information Service

U.S. residents may call the Cancer Information Service (CIS), NCI's contact center, toll free at 1-800-4-CANCER (1-800-422-6237) Monday through Friday from 9:00 am to 9:00 pm. A trained Cancer Information Specialist is available to answer your questions.

Food and Drug Administration

The Food and Drug Administration (FDA) regulates drugs and medical devices to ensure that they are safe and effective.

Food and Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993
Telephone: 1-888-463-6332 (toll free)
Website: http://www.fda.gov

Federal Trade Commission

The Federal Trade Commission (FTC) enforces consumer protection laws. Publications available from the FTC include:

  • Who Cares: Sources of Information About Health Care Products and Services
  • Fraudulent Health Claims: Don't Be Fooled
Consumer Response Center
Federal Trade Commission
600 Pennsylvania Avenue, NW
Washington, DC 20580
Telephone: 1-877-FTC-HELP (1-877-382-4357) (toll free)
TTY (for deaf and hard of hearing callers): 202-326-2502
Website: http://www.ftc.gov

Last Revised: 2021-08-09


If you want to know more about cancer and how it is treated, or if you wish to know about clinical trials for your type of cancer, you can call the NCI's Cancer Information Service at 1-800-422-6237, toll free. A trained information specialist can talk with you and answer your questions.


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