Caution! This is how dietary supplements endanger breast cancer patients

Caution! This is how dietary supplements endanger breast cancer patients

During Breast Cancer Awareness Month 2025, an important topic will be discussed: the interactions between breast cancer therapies and nutritional supplements. Many patients would like to support their well-being during their treatment with additional vitamins, minerals or herbal preparations. But caution is advised here, because combining cancer drugs with nutritional supplements can have unforeseeable consequences. The cancer information service of the German Cancer Research Center warns that interactions have not been sufficiently investigated and that the effectiveness of therapies can be impaired. It can happen that nutritional supplements accelerate the breakdown of medications in the liver or block their absorption in the body, which can disrupt the entire treatment. A balanced diet is usually enough to provide all the necessary nutrients, so additional supplements are often unnecessary.

Essential information clarifies that dietary supplements are not tested medicines and are therefore not subject to the same rigorous testing as therapies. An oversupply of certain nutrients can even be harmful to your health. The use of antioxidants such as vitamins C and E is viewed particularly critically. These can reduce the effectiveness of radiation therapy because they intercept the free radicals that contribute to the destruction of malignant cells. Further dangerous interactions occur with plant substances such as St. John's wort, which can accelerate the breakdown of the commonly used drug tamoxifen, which can significantly limit its effectiveness, according to [MRN News].

Scientific findings and recommendations

A recent study delved further into the topic, showing that women who took antioxidant supplements during their chemotherapy or radiation treatment had a worse prognosis. More than 2,000 women surveyed without metastases were studied, and the results were alarming: these women were more likely to have relapses and die during treatment. Therefore, scientists recommend taking antioxidants carefully during therapy. Antioxidants from foods such as cooking oils, fruit and vegetables, on the other hand, are considered unproblematic and should be given preference. The Cancer Information Service recommends, as a rule, consuming the antioxidants ingested through food and avoiding high-dose preparations, as does the Cancer Information Service.

Important information for patients

It is crucial for breast cancer patients to speak openly with their medical team about taking supplements. The exchange enables optimal coordination of all therapeutic approaches and helps to clarify possible risks and interactions. If several drugs or dietary supplements are taken at the same time, the risk of mutual influences that can affect therapy increases. In the worst cases, this can even lead to treatment failure or poisoning. These risks should not be underestimated, as the risk is particularly high if several medications are taken or if there are existing illnesses, reports Brstkrebs Deutschland.