Objective  To observe the effect of ketogenic diet on the growth of human colon cancer cells in nude mice and to determine its possible mechanisms.

  Methods  A total of 24 male BALB/C nude mice were injected subcutaneously with the tumor cells of the colon cancer cell line HCT116. These animals were randomized into two feeding groups. One group was fed with a ketogenic diet (KD group; n=12), and the other group was given a standard diet (SD group; n=12) ad libitum. Experiments were completed upon attaining a target tumor volume of 600 mm3 to 700 mm³. The two diets were compared based on body weight, serum glucose, ketone body, insulin, tumor growth, and survival time, which is the interval between tumor cell injection and attainment of target tumor volume.

  Results  The tumor growth was significantly more delayed in the KD group than in the SD group. Tumors in the KD and SD groups reached the target tumor volume at 33.8 ± 6.7 days and 24.8 ± 3.1 days, respectively. The ketone body in the KD group was elevated with a slight reduction in serum insulin, and the difference in serum glucose in the two groups was insignificant. Importantly, the KD group had significantly larger necrotic areas and less vessel density than the SD group.

  Conclusion  The application of an unrestricted ketogenic diet delayed tumor growth in a mouse xenograft model. Further studies are needed to address the mechanism of this diet intervention and its effect on other tumor-relevant functions, such as invasive growth and metastasis.