Highlights
Curcumin is the key active ingredient of the common spice Turmeric. Piperine, the key ingredient of Black pepper is often included in Curcumin formulations to improve its bioavailability. Many breast cancer patients are treated with a standard of care hormonal therapy called Tamoxifen. Along with such standard of care treatments, breast cancer patients often tend to look out for natural supplements like Curcumin (from Turmeric) with strong anti-inflammatory, antioxidant and anti-cancer properties to either improve their immunity, treatment efficacy, quality of life or reduce treatment side-effects. However, some of these supplements can end up harming the treatment. A clinical study discussed in this blog found such an undesired interaction between Tamoxifen drug treatment and Curcumin which is extracted from Turmeric. Taking Curcumin supplement while on Tamoxifen therapy can reduce the levels of the active metabolite of Tamoxifen and interfere with the therapeutic impact of the drug in breast cancer patients. Hence, one should avoid including Curcumin supplements as part of the breast cancer patients’ diet if undergoing Tamoxifen treatment. Also, it is important to personalize nutrition to the specific cancer and treatment to reap maximum benefits from nutrition and be safe.
Tamoxifen For Breast Cancer
Breast cancer is the most commonly diagnosed cancer and one of the leading causes of cancer-related death in women globally. One of the most common subtypes of breast cancer is the sex hormone dependent, estrogen (ER) and progesterone (PR) receptor positive and human epidermal growth factor 2 (ERBB2, also called HER2) negative – (ER+/PR+/HER2- subtype). The hormone positive subtype of breast cancer has a good prognosis with a very high 5-year survival rate of 94-99% (Waks and Winer, JAMA, 2019). Patients diagnosed with hormone positive breast cancers are treated with endocrine therapy such as Tamoxifen for breast cancer prevention and recurrence, after their surgery and chemo-radiation treatments. Tamoxifen acts as a selective estrogen receptor modulator (SERM), where it inhibits the hormone receptors in breast cancer tissue to reduce the survival of the cancer cells and reduce risk of relapse.

Curcumin- The Active Ingredient of Turmeric
A cancer diagnosis brings about major lifestyle changes in individuals including a trend towards the use of natural plant-derived supplements that are known to have anti-cancer properties, boost immunity and general wellbeing. Results of recent studies have shown that more than 80% of cancer patients use supplements including complementary and alternative medicine (Richardson MA et al, J Clin Oncol., 2000). Curcumin, the active ingredient from the curry spice turmeric, is one such natural supplement that is popular among cancer patients and survivors for its anti-cancer and anti-inflammatory properties. Therefore, the likelihood of breast cancer patients taking Curcumin supplements (extracted from Turmeric) while on Tamoxifen therapy is high. Curcumin is known to have poor absorption in the body and therefore it is commonly used in a formulation with piperine, a component of black pepper, that helps increase its bioavailability significantly (Shoba G et al, Planta Med, 1998).
Foods to Eat After Cancer Diagnosis!
No two cancers are the same. Go beyond the common nutrition guidelines for everyone and make personalized decisions about food and supplements with confidence.
Curcumin (from Turmeric) & Tamoxifen Drug Interactions in Breast Cancer
The oral drug Tamoxifen is metabolized in the body into its pharmacologically active metabolites through the cytochrome P450 enzymes in the liver. Endoxifen is the clinically active metabolite of Tamoxifen, that is the key mediator of efficacy of tamoxifen therapy (Del Re M et al, Pharmacol Res., 2016). Some earlier studies done on rats had shown that there is a drug-drug interaction between Curcumin (from Turmeric) and Tamoxifen because Curcumin inhibited the cytochrome P450 mediated metabolism of tamoxifen conversion to its active form (Cho YA et al, Pharmazie, 2012). A recently published prospective clinical study (EudraCT 2016-004008-71/NTR6149) from the Erasmus MC Cancer Institute in the Netherlands, tested this interaction between Curcumin and Tamoxifen in breast cancer patients (Hussaarts KGAM et al, Cancers (Basel), 2019).
In this study they tested the effect of Curcumin alone and Curcumin with its bio-enhancer Piperine when taken concurrently with Tamoxifen in 16 evaluable breast cancer patients. Patients were given Tamoxifen for 28 days prior to the study to ensure steady-state levels of Tamoxifen in all the subjects. Patients were then administered 3 cycles in 2 randomly segregated groups with different sequence of the cycles. Tamoxifen was given at a constant dose of 20-30 mg during the 3 cycles. The 3 cycles included Tamoxifen alone, Tamoxifen with 1200 mg Curcumin taken three times daily, or Tamoxifen with 1200 mg Curcumin and 10 mg Piperine taken three times daily. Levels of Tamoxifen and Endoxifen were compared with and without Curcumin alone and with the addition of the bio-enhancer Piperine.
This study indicated that the concentration of the active metabolite Endoxifen decreased with Curcumin and further decreased with Curcumin and Piperine taken together. This decrease in Endoxifen was statistically significant.
Conclusion
In summary, if Curcumin supplement is taken along with Tamoxifen therapy, it can lower the concentration of the active drug below its threshold for efficacy and potentially interfere with the therapeutic impact of the drug. Studies such as these cannot be ignored, although in a small number of breast cancer patients, and provide a caution for women taking tamoxifen to choose the natural supplements they take carefully, that do not interfere with the cancer drug efficacy (therapeutic impact) in any way. Based on this evidence, Curcumin does not seem to be the right supplement to be taken along with Tamoxifen as it interferes with the therapeutic efficacy.
What food you eat and which supplements you take is a decision you make. Your decision should include consideration of the cancer gene mutations, which cancer, ongoing treatments and supplements, any allergies, lifestyle information, weight, height and habits.
The nutrition planning for cancer from addon is not based on internet searches. It automates the decision making for you based on molecular science implemented by our scientists and software engineers. Irrespective of whether you care to understand the underlying biochemical molecular pathways or not - for nutrition planning for cancer that understanding is needed.
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Personalized Nutrition for Cancer!
Cancer changes with time. Customize and modify your nutrition based on cancer indication, treatments, lifestyle, food preferences, allergies and other factors.
Cancer patients often have to deal with different chemotherapy side effects which affect their quality of life and look out for alternative therapies for cancer. Taking the right nutrition and supplements based on scientific considerations (avoiding guesswork and random selection) is the best natural remedy for cancer and treatment related side-effects.