Evaluation of vitamin‐producing and immunomodulatory lactic acid bacteria as a potential co‐adjuvant for cancer therapy in a mouse model

To evaluate a mixture of selected lactic acid bacteria (LAB) (a riboflavin‐producer, a folate‐producer and an immunomodulatory strain) as co‐adjuvant for 5‐fluorouracil (5‐FU) chemotherapy in cell culture and using a 4T1 cell animal model of breast cancer. The viability of Caco‐2 cells exposed to 5‐FU and/or LAB was analysed. Mice bearing breast tumour were treated with 5‐FU and/or LAB. Tumour growth was measured. Intestinal mucositis (IM) was evaluated in small intestine; haematological parameters and plasma cytokines were determined. The bacterial mixture did not negatively affect the cytotoxic activity of 5‐FU on Caco‐2 cells. The LAB mixture attenuated the IM and prevented blood cell decreases associated with 5‐FU treatment. Mice that received 5‐FU and LAB mixture decreased tumour growth and showed modulation of systemic cytokines modified by both tumour growth and 5‐FU treatment. The LAB mixture by itself delayed tumour growth. The mixture of selected LAB was able to reduce the side‐effects associated with chemotherapy without affecting its primary anti‐tumour activity. This bacterial mixture could prevent the interruption of conventional oncologic therapies by reducing undesirable side‐effects. In addition, this blend would provide essential nutrients (vitamins) to oncology patients.