Kefir, a probiotic mixture of kefir grains mixed with raw milk or water that has various health benefits, may also have anticancer properties, a study published in Medical Oncology has shown.

Probiotics, in particular lactic acid bacteria (LAB), are thought to stimulate the immune system, and data from several studies have suggested that kefir may positively affect apoptosis, proliferation, and the anti-oxidative process in cancer.

Kefir has immunomodulatory and anti-inflammatory effects, which are thought to be contributing factors in cancer. Kefir’s bioactive peptides may increase macrophage production and phagocytosis and nitric oxide formation. TNF-α and cytokines such as interleukin (IL)-5, IL-6, IL-1β, and IL-12 are increased, and IL-8 is decreased, which lead to an improvement of inflammatory responses. Kefir can also suppress the T helper-2 immune response and activate T helper-1 immune responses, inducing an anti-allergy effect.

Kefir’s anticancer activity stems from its ability to decrease TGF-α, TGF-β, and Bcl2, and increase Bax, which leads to the induction of apoptosis. Low levels of TGF-α and TGF-β have antiproliferative effects in cancerous cells. Kefir can cause DNA cleavage by activating Ca/Mg dependent endonucleases, and induce ROS-mediated apoptosis.

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The anti-oxidative effects of kefir are demonstrated by its ability to increase levels of glutathione peroxidase and decrease levels of malondialdehyde. Kefir can also bind to 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide radicals and also inhibit linoleic acid peroxidation, exerting an anticarcinogenic effect by acting as an antioxidant.  

Methyl methanesulfonate, sodium azide, and aflatoxin B1, factors that increase mutagenicity, may be better controlled by the high levels of butyric, palmitic, palmitoleic, and oleic acids, and conjugated linoleic acid isomers that are found in kefir.