Cisplatin (Platinol) is a platinum-based chemotherapy drug that is used in combination with other drugs for advanced breast cancer and for triple negative disease (ER-/PR-/HER2-). Platinum-based drugs, or platins, cause crosslinking of DNA strands, thereby interfering with DNA repair and synthesis, and subsequently inducing apoptosis (programmed cell death) in cancer cells.g
While there is extensive research on the interaction of diet with chemotherapy drugs such as Adriamycin and Taxol (both used in early stage disease), little research is available for cisplatin. Therefore, while we are not able to produce an extensive article devoted to cisplatin, we present a brief summary of the available results to date here.

Overall diet during cisplatin treatment

It is important for breast cancer patients on cisplatin to avoid consuming foods or taking supplements that will lessen the cytotoxic impact of this drug (and any other drugs in the chemotherapy regimen) on cancer cells. Note that compounds that provide relief from chemotherapy side effects might also provide some protection to breast cancer cells. In fact, while various micronutrients found in fruits, vegetables and other foods have been shown to help protect against breast cancer development and metastasis, some micronutrients, especially in concentrated form, could enable breast cancer cells to survive chemotherapy.
The goal should be to eat a healthy diet that meets nutritional needs while avoiding harmful foods that can promote breast cancer. It is more important to avoid unhealthy foods (fast food, junk food, meals consisting mostly of highly refined carbohydrates, unhealthy fats (including most vegetable oils), red meat, and fried food) than to consume cancer-fighting foods. The purpose of food during chemotherapy is to enable patients to feel well enough to continue treatment, not to eliminate side effects that may in fact be associated with successful treatment.

Foods that enhance cisplatin's effects or safely reduce side effects

The following foods are good sources of compounds that have been shown to increase the anti-cancer effects of cisplatin and/or safely reduce its side effects:
Fruits and vegetables should be washed thoroughly before cooking or consuming. This includes the exterior of fruits with peels such as lemons.
Topical application of honey has been shown to be effective in reducing the severity of chemotherapy-induced oral mucositis.
Aspirin is the best choice of over-the-counter pain medications (assuming the gastrointestinal and other side effects can be tolerated) since aspirin has been shown to lower the concentration of cisplatin required to exert its cytotoxic action on tumor cells. On the other hand, the prescription painkiller Celebrex has been shown to reduce the effectiveness of cisplatin. The anti-diabetic drug metformin has been shown to increase the cytotoxic treatment effects of cisplatin.

Supplements for patients being treated with cisplatin

There is no supplement or combination of supplements that has been proven to reliably reduce the risk of breast cancer recurrence in women. Attempting to take advantage of the apparent treatment effects of micronutrients and other dietary components by using supplements carries the risk of adverse and paradoxical effects, including promoting breast cancer growth and metastasis.
What is known is that when a beneficial micronutrient is administered at low doses by consuming food, it is likely to have subtle chemopreventive effects, whereas when the same micronutrient is administered at high doses, it is more likely to have pharmacological effects, with mostly unknown results. Therefore, it is best to obtain beneficial compounds by consuming food, if possible. Supplements should be used if medically necessary or to make up for deficiencies that are difficult to correct through diet.
The following supplements generally have been found to be safe and beneficial for those being treated with cisplatin:
CoQ10 (if needed for heart health)100 to 400 mg/day
Fish oil (from wild-caught fish)1000 to 2000 mg/day
Vitamin D1000 to 2000 IU/day
Avoid taking supplements during the two days before, the day of, and the day after each chemotherapy treatment. Please consult your oncology team for advice concerning your situation and dosages. It might make sense to be tested for deficiency in vitamin D and plan for follow up to determine if your reading has reached a desirable level.

Foods that should be limited or avoided during cisplatin treatment

The following have been reported to interfere with the effectiveness of cisplatin:
Please note that, unlike salmon and the closely-related Arctic char, research suggests that herring, sardines, anchovies, mackerel, lake trout and similar fatty fish should not be consumed the day before through the day after a chemotherapy treatment. Such fish have been shown to incorporate two fatty acids (12-oxo-5,8,10-heptadecatrienoic acid (KHT) and hexadeca-4,7,10,13-tetraenoic acid (16:4(n-3))) which can induce resistance to platinum-based chemotherapy drugs. In addition, these fish should be consumed only in moderation during the remaining days of each cycle.

Supplements & other that should be avoided during cisplatin chemotherapy

The following supplements and other exposures have been found to interfere with the effectiveness of cisplatin. That is not to say that most other supplements are safe to take; there are no relevant scientific studies concerning the interactions between most supplements and cisplatin.
Many women develop abnormally low iron levels during cisplatin chemotherapy which must be treated. However, excess iron is also to be avoided since it has been shown to reduce the effectiveness of cisplatin. Curcumin (found in turmeric) has been shown to be an iron chelator (a compound that removes iron from the body) as well as a copper chelator. Turmeric might also protect the brain from chemotherapy, thereby possibly reducing chemo brain.
Please see our article on how to optimize your breast cancer diet for information on what to eat during all stages of treatment and recovery.