A new study found that high-fat, low-carb diets like the ketogenic diet helped boost certain cancer treatments in mice.

Keto diets didn't help without the drugs, however, suggesting diet is only one part of the equation.

The first human trial of a similar diet-and-drug combo is set to begin in the fall.

The research aligns with other findings about how tumors thrive on sugar.

Cancer researchers may have just found a groundbreaking new way to make cancer-zapping drugs more effective.

In a recent study, a team of doctors put mice with cancer on low-carb, high-fat ketogenic diets while administering a treatment called a PI3K inhibitor that's designed to kill tumors. The results, which were reported in the journal Nature last week, showed that pairing that treatment with a keto diet significantly improved the cancer-busting effects of the medication.

"We could basically arrest the growth of the tumor," Siddartha Mukherjee, the study's lead co-author and an oncologist at Columbia University's Irving Medical Center, told Business Insider.

Mukherjee, who wrote the Pulitzer Prize-winning book "The Emperor of All Maladies: A Biography of Cancer," said he'd like to see cancer doctors taking a more holistic approach to treatment overall, and that diets like the keto plan could play a key role.

"We hope very much that we would see, in the future, a much more careful assessment of what diet means and how diet can affect chemotherapy," he said.

This fall, Mukherjee's team plans to try the diet-plus-drug combo out in people.

Mice on a high-fat diet

The 18 doctors and researchers behind the study come from Weill Cornell Medicine, Columbia University, and New York-Presbyterian hospital. The team also included Lewis Cantley, who's been studying cancer treatments and diet for decades.

The experiment worked like this: doctors put the rodents on a keto diet, which forces the body to rely on fats for fuel by strictly limiting carbohydrates and sugar as energy sources.

Then the researchers administered the PI3K inhibitor drugs. PI3K (short for phosphoinositide-3-kinase) is an enzyme that's linked to cancer growth in cells. PI3K inhibitors are a relatively new type of drug — only two are FDA-approved so far — designed to turn off PI3K pathways that fuel cancer cell growth. When it works, the treatment essentially kills the enzyme, which prevents the disease from spreading, leading tumors to die.

The problem is that when patients take PI3K drugs, their blood-sugar levels often spike in response. That, in turn, activates PI3K enzymes all over again, and the cancer continues to spread.

"It's like hitting the gas and the brake at the same time," study author Benjamin Hopkins, who worked in Cantley's lab, told Business Insider.

The new study suggests that a keto eating plan could help mitigate that effect. In mice, the diet reliably controlled blood sugar and insulin levels, lowering them on average 90%, and thus improved the PI3K drug's ability to keep a mouse's cancer from spreading. Results varied depending on what kind of cancer the mice had (pancreas, breast, endometrial, bladder cancers, and a leukemia were all tested), but for some mice, going keto doubled their lifetimes.

The researchers also tried using a couple of drugs designed to control blood-sugar levels, but found that the keto diet worked best.

The finding could be a game changer for the emerging class of PI3K drugs, which has often performed poorly in trials because of the problematic blood sugar spikes.

The research team is now preparing for its first small-scale trial of the keto-based technique in people, which is slated to start in October. The first human test subjects will be a group of around 40 patients with lymphomas and endometrial cancers, Mukherjee said. The medication used will be an FDA-approved PI3K-inhibitor called copanlisib, manufactured by Bayer under the brand name Aliqopa.

Food as medicine

For centuries, clinicians have known that what we eat is a critical component of our health.

Ancient Greek physician Hippocrates is often credited with coining the phrase "let food be thy medicine, and medicine be thy food," but he probably never actually said that.

The keto diet is a high-fat plan. Butter, meats, eggs and leafy greens are all acceptable. Shutterstock

Nonetheless, it's an approach Mukherjee and his colleagues hope to bring medical attention back to.

"We now know through a variety of mechanisms that diet can also have a profound effect on human physiology," Mukherjee said. "It should really be thought about as something that can potentially act in conjunction with medicine."

The low-sugar keto diet has already been found useful for some other health conditions. It can help control epileptic seizures that are not responsive to anti-epileptic drugs, and also helps patients with Type 2 diabetes lose weight and manage their blood sugar. Since cancer cells have been found to thrive on sugar as fuel, it makes sense that a treatment designed to cut back on sugar and control blood-sugar levels might have potential for cancer treatment, too.

But a word of caution is in order. Just because keto diets were shown to have promise for mice with cancer in a lab doesn't mean there are any definite implications for people. And the results also don't suggest that you can prevent cancer by cutting sugar and carbs from your diet — there hasn't yet been any conclusive research on what keto diets might do for healthy people long-term.

In fact, the study suggested that keto diets can, in some cases, hurt cancer treatment. Mice who followed the high-fat keto plan without the PI3K inhibitor drugs on board saw no benefit to treating their cancers, and in mice with leukemia, the keto plan caused their tumors to grow faster than normal.

"You have to be very careful and not use pop knowledge that 'oh, sugar's bad,'" Mukherjee said.

Still, the keto diet certainly warrants more research for its potential to help cancer patients maintain the low insulin levels that are a key part of successful treatment.