Herceptin (trastuzumab) is a monoclonal antibody used to treat HER2/neu overexpressing (HER2+) breast cancer. HER2/neu has a role in the signaling pathways leading to cell growth and differentiation, which accounts for the reputation of aggressiveness of this type of breast cancer. Herceptin binds selectively to the HER2 protein, thereby reducing cancer cell growth and proliferation. Herceptin normally is administered intravenously alone or in combination with a chemotherapy regimen. There are a few foods and spices that have been shown to amplify the effects of Herceptin, thereby increasing its effectiveness.

Herceptin and other similar monoclonal antibodies can result in side effects such as flu-like symptoms (fever, nausea, vomiting, diarrhea, increased cough, headache), low white blood cell count, anemia, increased infections, muscle pain, and lung and heart damage. There are some foods that support heart health while also being associated with lower risk of breast cancer or its recurrence. Other foods could have the opposite effect.

Foods that amplify the anti-cancer effects of Herceptin

The following foods are good sources of compounds that have been found to amplify the effects of Herceptin against HER2-overexpressing breast cancer:

Arctic char
Bell peppers
Bok choy
Broccoli & broccoli sprouts
Brussels sprouts
Cabbage, white or green
Carrots, purple or black
Cherries, especially sour or tart
Currants, black
Flaxseed & flaxseed oil
Green tea

Hot peppers
Lake trout
Olive oil, extra-virgin
Passion fruit
Plums, purple or red
Raspberries, black
Rice, black or purple
Salmon, wild
Sweet potatoes, purple
Walnuts & walnut oil

Olive oil, parsley, celery, green tea and cruciferous vegetables have been shown to counteract Herceptin resistance in the laboratory.

Foods that counteract Herceptin's toxic side effects

Flaxseed has been found to protect the lungs. The foods below have been found to support heart health while also protecting against breast cancer:

Arctic char
Canola oil
Collard greens
Flaxseed oil
Lake trout

Mustard greens
Olive oil
Salmon, wild
Turnip greens

Breast cancer patients receiving chemotherapy at the same time as Herceptin should also incorporate appropriate food choices for the drugs used (e.g., Taxol or Adriamycin).

Foods, supplements & drugs that could interfere with Herceptin treatment

Grapefruit should be avoided during Herceptin and chemotherapy treatment because of potential grapefruit-drug interactions.

Although we do not recommend supplementation with CLA (conjugated linoleic acid), we want to advise those who do so to avoid the t10,c12-CLA isomer (referred to on some supplement labels as Trans-10, Cis-12). The t10,c12 CLA isomer can damage the heart and was found to enhance mammary tumor development in two separate animal experiments.

Many women undergoing treatment for breast cancer develop abnormally low iron levels. Since blood counts usually are monitored periodically, these women will be identified and treated. However, based on the available evidence, women on Herceptin who are not iron-deficient should avoid iron supplements (including those in multivitamins), as well as sources of heme iron (from non-plant foods) such as red meat, shellfish, or any type of liver. The body absorbs heme iron more effectively than nonheme iron from plant sources such as spinach and dry beans. Tumeric contains curcumin, which has been shown to be an iron chelator, which may be helpful in reducing iron stores. However, curcumin supplements are not recommended.

Anti-anemia drugs based on erythropoietin have been shown to reduce the effectiveness of Herceptin. Erythropoietin controls the body's red blood cell production and is the basis for drugs such as epoetin alfa (Procrit), epoetin beta (Mircera), and darbepoetin alfa (Aranesp). These drugs should not be avoided if they are necessary to treat chemotherapy-related anemia, thereby eliminating the need for a blood transfusion. However, based on the available evidence, they should be used as sparingly as possible during Herceptin treatment.

The Chinese medicine Si-Wu-Tang has been shown to interfere with the effectiveness of Herceptin.

Foods detrimental to heart health

The following foods have been found to be potentially detrimental to heart health as well as being associated with increased risk of breast cancer and should be limited or avoided:


Liver, any type
Milk, whole
Partially-hydrogenated soybean oil and other sources of trans fats
Processed meats
Salt, excessive

Additional comments

We caution against taking curcumin, epigallocatechin-3-gallate (EGCG), 3,3'-diindolylmethane (DIM), indole-3-carbinol (I3C), or CLA in supplement form because of the possibility of unintended consequences. Safe and effective dosages for these supplements during Herceptin treatment or chemotherapy have not been established. There is some evidence that taking anti-oxidant vitamin supplements could potentially enable early-stage HER2-positive tumor cells to survive when they otherwise would die.

Breast cancer patients and survivors with HER2/neu-overexpressing breast cancer should eat a wide variety of the foods on our recommended list and limit or avoid those on our avoid list, in addition to emphasizing the foods and spices on the lists above. Please also see our article on how to optimize your breast cancer diet for information on what to eat during all stages of treatment and recovery.

Below are links to recent studies on Herceptin. For a more complete list of studies, please click on the tag Herceptin.