A low-carb diet might prevent some types of tumors from rapidly growing—at least in mice, new research finds.

In a recent Canadian study, 70 percent of mice on a high-carb western-like diet developed tumors, while only 30 percent of the low-carb group grew tumors. The details of the diets: The high-carb mice consumed a diet of 55 percent carbs, 23 percent protein, and 22 percent fat; the low-carb group ate a diet of 15 percent carbs, 25 percent fat, and 60 percent protein.

The diet connection

How might diet affect tumors? “Normal cells can function using energy from both fat and sugar [carbohydrates],” says study coauthor Gerald Krystal, Ph.D., professor at the University of British Columbia. “But cancer cells depend more heavily on glycolysis, a process that breaks down only sugar, for energy.”

The theory: When your blood sugar spikes after a high-carb meal, your cancer cells have a feast, allowing them to rapidly multiply. (Researchers have shown this finding using human cancer cells isolated in a lab setting.) Experts, including Krystal, speculate that depriving the body of carbohydrates allows normal cells to live off body fat, but kills cancer cells, since they can break down energy from blood sugar only.

Could this affect people?

The million-dollar question: Does the carb/cancer connection apply to humans? “A mouse’s blood sugar can drop by as much as half when on a low-carb diet,” says Eugene Fine, M.D., researcher at the Albert Einstein College of Medicine, who peer-reviewed the paper. “When you put a human on a low-carb diet, the blood sugar levels drop, but still stay well within the normal range.” This doesn’t invalidate the findings, he says. “Most cancer research involves interpreting results from mice studies—and these results are very promising.”

Human research on the topic is limited. A 1995 Case Western Reserve University case report on two children with brain cancer showed that 8 weeks of a high-fat, low-carb ketogenic diet resulted in 22 percent less tumor metabolism, which means that the tumor had stopped growing.

But still, this is only two people. “Unfortunately, it’s difficult to conduct dietary clinical trials in people,” says Dr. Fine. Oncologists aren’t usually on board since there isn’t a lot of research on diet and cancer and they’re not trained in administering diets to begin with. Not to mention, researchers can only test people in the final stages of cancer—it could be more effective before the cancer progresses.

Frankly, diet isn’t likely to be a clean-cut cure for cancer, but researchers think it has potential—Dr. Fine’s group at Einstein completed a study of carbohydrate restriction for one month as cancer therapy in humans. If published, he believes that these results will support the idea that low-carb diets can complement cancer drugs as therapy.

What can you do to prevent cancer?

Are there other nutritional strategies that could help prevent cancer? Consider increasing your vitamin D intake. In a Creighton University study, women who supplemented their diets with 1,000 international units of vitamin D every day had a 60 percent to 77 percent lower incidence of all cancers over a 4-year period than the placebo group. “I don’t think the effect is limited to women,” Joan Lappe, Ph.D., and lead study author told us in 8 Ways to Prevent Any Kind of Cancer. “Vitamin D is necessary for the best functioning of the immune system—it causes early death of cancer cells.” Take a daily vitamin D supplement with 1,100 to 2,000 IU