Nutrition & Food Science

Purpose – Kefir is a probiotic grown with milk, with a slightly sour flavor and has been consumed for thousands of years. Kefir grains contain bacteria and yeast. In the past, kefir was administrated as a drug against tuberculosis, cancer and gastrointestinal disorders. The purpose of this paper is to investigate the potential anticancer properties of kefir and its ability to affect natural killer cells' (NKCs') activity.

Design/methodology/approach – The assay of cytotoxic activity of NKCs by cytometric analysis was used, which included four stages: isolation of natural killers; quantification of target cells; incubation of natural killers with target cells at ratios of 12.5:1, 25:1 and 50:1 in CO2 incubator; and measurement of cells with flow cytometer. The same procedures were repeated, but the third stage was modified with the addition and incubation of 50, 75, and 100?µL kefir (of 24 hour culture with 3.5 per cent fresh milk) with K562 and leiomyosarcoma cells lines, and kefir and NK cells with K562 or LMS cell lines.

Findings – The results showed that kefir's cytotoxic activity without the presence of NKCs reached an average of 85 per cent in both cell lines. With the addition of NK cells in kefir, the cytotoxic activity further increased by 10 per cent. Kefir alone did not cause any statistically significant death in NK cells. Kefir seems to have significant cytotoxic action by itself without stimulating NK cells in a significant manner. However, further studies are needed to establish the role of kefir in the prevention and treatment of neoplasmatic diseases.

Originality/value – The paper provides information and new data, for nutritionists and clinical dietitians, about the effects of kefir in the prevention of cancer.