Just before UV irradiation, only the lower stage was given NKG Kefir. Immediately after, 5 minutes, and 10 minutes after ultraviolet irradiation, the active oxygen concentration in the cells was observed. As a result, it was found that the cells given NKG kefir had the concentration of reactive oxygen decreased with the passage of time. NKG Kefir has been found to have the effect of repairing and recovering cells from damage caused by ultraviolet light.