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The health benefits of tea have been recognized for thousands of years. But if you’re on the breast cancer drug tamoxifen (Soltamox), tea’s natural compounds might affect how it works.
A MyBCTeam member was surprised by this and said, “I was not aware of herbal teas being an issue with this medication.”
If this surprises you too, here’s what you should know.
Tamoxifen is a hormonal therapy used to treat or prevent breast cancer. It blocks the effect of estrogen on breast cancer cells.
For tamoxifen to work, your liver needs to transform it into its active form. The active form is called endoxifen. Any food, drink, or drug that interferes with this process could make tamoxifen less effective.
A group of proteins in your liver called cytochrome P450 enzymes (or CYP enzymes) helps activate tamoxifen. These proteins also help your body break down the drug to eliminate it.
Specific CYP enzymes are involved in the process. For example, CYP2D6 is mainly responsible for converting tamoxifen to endoxifen. Another subgroup, CYP3A4, also plays a role in activating tamoxifen.
Substances that interfere with CYP enzymes may block the activation of tamoxifen. This effect makes the drug less effective, in theory.
Other substances speed up the metabolism of tamoxifen. And if your body gets rid of the drug too fast, it may not work as well.
Sometimes researchers use what’s known about tea compounds and CYP enzymes to help predict how drinking tea affects tamoxifen treatment. But these relationships don’t always play out in real human studies.
Besides water, green tea is one of the most consumed beverages in the world. People may drink green tea because they’ve heard it can:
Green tea and green tea supplements are popular among people with breast cancer.
That’s because they contain anticancer compounds called antioxidants. “I have green tea daily,” shared a member of MyBCTeam.
Antioxidants help guard against cell damage and inflammation. As a result, many researchers believe green tea may help protect against cancer and inflammatory conditions, like heart disease.
Epigallocatechin-3-gallate (EGCG) is the main antioxidant in green tea. Studies show EGCG promotes the destruction, or apoptosis, of abnormal cells in the body that may be cancerous.
Despite green tea’s likely health benefits, there’s not enough evidence to support claims that green tea can treat or prevent cancer.
EGCG (a natural compound in green tea) can change how your body handles some medicines. For example, green tea may lower how much of certain heart medicines your body absorbs. This doesn’t mean green tea is a “cancer treatment blocker,” but it’s a reminder that natural products can still affect medications.
However, EGCG was found to increase the action of tamoxifen when tested in a lab, potentially making the drug stronger. But a small human study looked at a green tea extract supplement in capsules, and it found no meaningful change in endoxifen levels in 14 people taking tamoxifen. That study was about a supplement, so it doesn’t perfectly match drinking brewed green tea, but it suggests green tea products may not strongly change tamoxifen levels for everyone.
Some interactions may happen because green tea affects how medicines are absorbed in the gut and sometimes how the liver breaks them down.
Brewed green tea (a normal cup) is different from green tea extracts in pills or powders. Extracts can be much stronger, so they may be more likely to cause side effects or interact with medicines.
Moderately brewed green tea is generally safe for most people. But it does contain caffeine. If you’re sensitive to caffeine’s effects, you may want to choose decaf or limit your intake.
If you use a green tea supplement, it can come with other risks. Supplements can be highly concentrated and may have substances in them that aren’t listed on the label. In some cases, green tea supplements may be harmful to the liver.
Always ask your healthcare team before including new products in your routine, even if they’re natural supplements.
Chamomile is a common ingredient in herbal tea. It’s often promoted as a relaxing or calming herb.
Some studies support the benefits of chamomile for anxiety and depression. When added to mouthwashes, it may help reduce irritation and swelling associated with radiation therapy and chemotherapy.
Even though chamomile is generally considered safe, there’s some evidence that it may interact with tamoxifen. Some lab studies (not strong human studies) suggest chamomile might affect enzymes that help your body process medicines, including tamoxifen.
We don’t have clear proof that a normal cup of chamomile tea changes how tamoxifen works in real life, but it’s still smart to be cautious with concentrated products.
A cup of chamomile tea probably isn’t strong enough to worry about in regard to the effects of tamoxifen. Some people worry chamomile could act a little like estrogen, but this isn’t well proven in humans. If you have breast cancer, it’s a good idea to check with your oncology team — especially before using chamomile in supplements or large amounts.
In addition, the most common side effect of chamomile is an allergic reaction. Chamomile is in the same family of plants as ragweed, so if you have an allergy, you should avoid it.
There’s also a possibility that chamomile will interact with other medications that are processed through the liver. You shouldn’t assume that chamomile is completely harmless, especially in a concentrated form.
Ginger is a spice that comes from the rhizome (underground stem) of the ginger plant. It’s been used in traditional medicine for thousands of years.
Ginger is especially popular for easing nausea and vomiting. Common uses include:
However, the evidence is mixed. In addition, ginger supplements may be helpful for menstrual cramps in some people.
Studies show that compounds in ginger root affect the action of several CYP enzymes. Theoretically, this could also impact the efficacy of tamoxifen. However, it’s unknown how ginger will affect your risk of breast cancer if taken with tamoxifen.
Ginger has been used safely in many clinical trials. The most common side effects include:
Ginger can make it harder for your blood to clot, increasing your bleeding risk. If you’re taking a ginger supplement, you may need to stop taking it before you have surgery.
Complementary and alternative medicines, like teas, can be especially intriguing for people with cancer. However, just because something is natural doesn’t mean it’s safe. So far, there isn’t any evidence that a dietary supplement can treat or prevent cancer.
Some clinicians suggest being careful with grapefruit and grapefruit juice while taking tamoxifen. The evidence that grapefruit clearly weakens tamoxifen is limited, but it’s still worth asking your oncology team what they recommend.
In addition, alcohol may worsen your side effects and affect your liver health. Alcohol itself is associated with a higher breast cancer risk. People with breast cancer should discuss safe limits for alcohol with their oncology team, regardless of their treatment plan.
Other foods and dietary supplements that might interfere with tamoxifen include:
Talk to your oncologist or a registered dietitian about which foods and drinks to eat or avoid during breast cancer treatment.
On MyBCTeam, people share their experiences with breast cancer, get advice, and find support from others who understand.
How does taking tamoxifen affect your food and beverage choices? Let others know in the comments below.
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Can you provide the same info about teas and their safety for people taking an aromatase inhibitor?
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I guess I wouldn't take them together, just like not taking antioxidants while on chemo or radiation. Everything we take into our bodies has a reaction to something in our bodies. No two people are… read more
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