Kefir also has varying degrees of benefit for different types of cancer.

Previous studies demonstrated that patients with breast cancer who took kefir extracts experienced a dose-dependent inhibition of MCF-7 cell growth, and also showed that kefir cell-free fraction has modulatory effects on the immune response in tumors and mammary glands.

Patients with leukemia who take kefir may experience increased apoptosis and decreased cell proliferation. Previous studies have shown that kefir may upregulate TGF-β1 while downregulating TGFα expression, a cytokine responsible for inducing cell proliferation and replication, in a time-dependent and dose-dependent manner


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Kefir may also suppress the HMV-1, SK-MEL, and TIG-1 morphological alterations in melanoma cell lines induced by UVC irradiation. Even after UVC irradiation of HVM-1 cells, application of kefir extract led to a reduction of intracellular reactive oxygen species, and may lead to the inhibition of UV damage.

Kefir may cause a declined polarization of mitrochondrial membrane potential (MMP) and reduced Bcl2 expression, which have been associated with apoptosis induction in gastric cancer cells. Data from a study showed that kefir halted the G1/S phase transition of the SGC7901 cell line, and downregulated bcl-2 and overexpressed bax, inducing apoptosis.

High levels acetic acid and lactic acid found in kefir may also have antioxidant effects which decrease DNA damage. In colorectal cancer (CRC) cell lines, kefir may cause cell cycle arrest in the G1 phase and decrease TGF-β1 and TGF-α, while upregulating Bax/Bcl2.

Prior studies have demonstrated that kefir may inhibit sarcoma tumor growth. Milk kefir inhibited tumor growth by 64.8% in mice-bearing sarcoma tumor cells, and soy milk kefir inhibited growth by 70.9%. Data from studies conducted in human patients with sarcoma have also supported the anticancer activity of kefir.

The authors of the review concluded that “according to the evidence in the literature, we can ascertain that kefir is one of the best therapeutic natural ingredients, applying its anticancer effect through different cellular and molecular pathways. Kefir is likely to be recognized for effective treatment of malignancies and as an anticancer agent in the near future.”

Reference

1. Sharifi M, Moridnia A, Mortazavi D, Salehi M, Bagheri M, Sheikhi A. Kefir: a powerful probiotics with anticancer properties [published online September 27, 2017]. Med Oncol. doi: 10.1007/s12032-017-1044-9