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Researchers are learning how diet may affect cancer risk. Getty Images
  • Maintaining blood sugar levels can be helpful for your overall health.
  • Early research also points to the benefits of keeping blood sugar levels low to help fight cancer.
  • Past research has found that certain tumors may rely on high glucose levels.

Keeping blood sugar levels even throughout the day may help you avoid afternoon energy crashes. It might also ward off or help you manage diabetes.

Now, early research published in the journal Cell Reports suggests that restricting your blood sugar might also help combat certain cancerous tumor growths.

Researchers from the University of Texas at Dallas restricted blood sugar levels in mice by feeding them a ketogenic diet — one that’s high in fat, moderate in protein, and low in carbs — and by giving them a diabetes drug that prevents the kidneys from reabsorbing glucose in the blood.

The combination of the diet and diabetes drug didn’t shrink the lung and esophageal cancers in the mice, but it did keep them from progressing.

“Both the ketogenic diet and the pharmacological restriction of blood glucose by themselves inhibited the further growth of squamous cell carcinoma tumors in mice with lung cancer,” Jung-Whan “Jay” Kim, PhD, corresponding author of the study and an assistant professor of biological sciences at UT Dallas, said in a press release.

Both elements actually showed promise independent of one another, too.

“The key finding of our new study in mice is that a ketogenic diet alone does have some tumor-growth inhibitory effect in squamous cell cancer,” Kim said. “When we combined this with the diabetes drug and chemotherapy, it was even more effective.”

However, Kim and his colleagues report that the keto diet and drug combination had no effect on non-squamous cell cancers.

The research is in the extremely early stages. It’s unclear if these results could be replicated in humans.

But it joins a growing body of evidence finding that certain diets, including the keto diet, may act as a complementary therapy for some people undergoing cancer treatment.

This finding in particular suggests certain tumors might be susceptible to glucose restriction.

It helps confirm earlier research by Kim and colleagues. Their 2017 study indicated that a certain type of cancer called squamous cell carcinoma (SCC) was particularly reliant on glucose to sustain itself and survive.

As part of their research, Kim and investigators also took blood samples from 192 people who had SCC of the lung or esophagus, plus blood samples from 120 people with lung adenocarcinoma, another type of cancer.

They measured the blood glucose levels in the samples and divided them by whether they were above or below 120 mg/dL, a common clinical measure of diabetes in blood sugar.

“Surprisingly, we found a robust correlation between higher blood-glucose concentration and worse survival among patients with squamous cell carcinoma,” Kim said.

“We found no such correlation among the lung adenocarcinoma patients. This is an important observation that further implicates the potential efficacy of glucose restriction in attenuating squamous-cell cancer growth,” he said.

In other words, people who had SCC and a high blood glucose level had worse survival rates compared to people who had other types of cancer.

This secondary finding indicates that blood glucose levels may also have an impact on the progression of cancer. Managing blood glucose levels during treatment may be an effective way to enhance conventional methods of cancer treatment.

“Manipulating host glucose levels would be a new strategy that is different from just trying to kill cancer cells directly,” Kim said. “I believe this is part of a paradigm shift from targeting cancer cells themselves. Immunotherapy is a good example of this, where the human immune system is activated to go after cancer cells.”

Cancer treatment and care have seen a shift in recent years.

While conventional treatments like surgery, chemotherapy, and radiation are still the primary means for eliminating cancerous tumors, researchers are seeking out complementary methods that may help stop the growth of cells, or even help defeat them.

These methods aren’t thought of as a way to replace traditional therapies like radiation. Instead, they’d be an additional aid in the fight against cancer.

In fact, one 2014 study already identified the keto diet “as an adjuvant therapy to conventional radiation and chemotherapies.”

In addition to helping regulate blood sugar levels, a keto diet could selectively induce metabolic oxidative stress in cancer cells. This could help make the cells more sensitive to treatments like chemotherapy and radiation.

“Ketogenic diets are known to interfere with tumor growth in more ways than one,” said Dr. William Li, author of “Eat to Beat Disease: The New Science of How Your Body Can Heal Itself.” “Reducing glucose takes away a fuel source for cancer cells. Unlike healthy cells, abnormal cancer cells have difficulty adapting metabolically to a low glucose situation, compromising their ability to survive.”

Li further explained, “But a ketogenic diet also triggers a chain reaction of at least three other cancer-fighting mechanisms. Less glucose means cells produce less IGF-1, a protein growth signal for cancer. Ketogenic diets also lower the tumor’s ability to produce another growth signal called VEGF. Tumors use this signal to grow a private blood supply. By cutting off the tumor blood supply, an effect called anti-angiogenesis, cancer cells become starved and can’t grow.”

But the ketogenic diet shouldn’t be considered standard care, says Quintin Pan, PhD, deputy scientific director at University Hospitals Seidman Cancer Center. It’s too early to know if the benefits outweigh possible risks.

“The anticancer benefits of a keto diet for cancer patients remain an open question and need to be addressed in a controlled clinical trial,” Pan told Healthline.

Pan also points out that the keto diet specifically is notoriously difficult to maintain.

People undergoing cancer treatment should always talk with their doctor before trying a new strict diet and discuss potential issues that may arise for them. Many people receiving chemotherapy are nauseous; they may not be able to stick with a very strict diet.

“Strict adherence to a keto diet is challenging, especially for cancer patients. And also, keto diets may lead to potential health risks,” Pan said. “It is important for cancer patients to have a conversation with their clinician team, doctor, and dietitian before starting on a keto diet.”

While there still needs to be more research, some experts are advising certain patients to see if the keto diet is right for them.

Elena Villanueva, DC, a functional holistic medicine expert and founder of Modern Holistic Health, says some treatment facilities are beginning to use the diet because of anecdotal reports and preliminary data that show promising signs.

“For those battling with cancer and for those who are in remission, the adaptation of a healthy ketogenic diet is showing many benefits,” she said. “Several oncology centers around the country have implemented ketogenic diets combined with standard cancer treatments because of the anticancer effects from eliminating sugars from the diet.”

If you’re undergoing cancer treatment, talk with your oncologist or healthcare provider before changing your diet in any manner.

Your doctor may refer you to a registered dietitian who has special training in oncology nutrition. The keto diet may be one of the options available to you, but it’s not a replacement for traditional cancer therapy like chemotherapy or radiation.

Additionally, it’s best to work with a professional who can make sure you’re able to maintain the keto diet and stay healthy.