Of mice and men and low-carbohydrate diets


We know from prior research that mice that have prostate cancer and are fed a no-carbohydrate ketogenic diet (NCKD) have smaller prostate cancer tumors and live longer than mice that are fed the mouse equivalent of a standard “Western” diet.

Humans, however, have a very hard time trying to live on an NCKD (which is 84 percent fat, 0 percent carbohydrate, and 16 percent protein). So Masko et al. compared the impact of diets with 10 and 20 percent carbohydrate to an NCKD in the same mouse model of prostate cancer.

They used a total of 150 male severe combined immunodeficient (SCID) mice that were initially fed as much as they wanted of a “Western” diet. Most of the mice (n = 140) were then injected with prostate cancer cells to start the formation of tumors. Two weeks later these 140 mice were randomized to one of three types of diet: the NCKD, a 10 percent carbohydrate diet, or a 20 percent carbohydrate diet. Ten mice were not injected with tumors and were fed on a 12 percent low-fat diet as a “control” arm for reference. All the mice were killed when their tumors reached a volume of  1,000 mm3.

The results of the study showed that:

  • All mice given the three low-carbohydrate diets were significantly lighter than those on the low-fat diet, even though they consumed more calories.
  • Among the three low-carbohydrate diets, the NCKD-fed mice were significantly lighter than the 10 or 20 percent carbohydrate diet mice.
  • Tumors were significantly larger in the 10 percent carbohydrate diet group on days 52 and 59, but at no other point during the study.
  • Diet had no effect on the mice’s survival.

Now the application of data from mouse models to people is fraught with all sorts of scientific problems, and there is no guarantee at all that what happens in mice will also happen in man. (Pace John Steinbeck!) However, it does seem interesting that — in mice — two different low-carbohydrate diets had an effect on prostate cancer-specific mortality that was similar to that of the NCKD diet.

Of course whether most men diagnosed with prostate cancer could actually manage to stay on a 10- or 20-percent carbohydrate diet for 20+ years is a whole different question.

In another study that appeared today — which is not specific to prostate cancer — Fung et al. have demonstrated that low carbohydrate diets based on high levels of plant-derived proteins and fats are associated with longer overall survival than low carbohydrate diets based on animal-derived fats and proteins. This is, of course, the type of diet advocated by Dr. Dean Ornish — and is no doubt wonderful for those who take joy in a diet high in lentils and beans.

Thirty years from now we may be worrying ourselves over issues like whether diet A (high in plant-based proteins and fats and low in carbohydrates) can offer a similar quality of life to diet B (high in animal-based proteins and fats and low in carbohydrates) and whether any loss of quality of life can be justified by a 10 percent mean increase in survival (from 85 to 93.5 years at time of death) for men with a history of prostate cancer.

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