Keto Diet and Cancer: What's the Latest Research?

We’re familiar with the keto diet as a popular approach for weight loss. But is there also evidence that this ultra-low-carb diet may be effective in helping to treat cancer, in conjunction with standard therapies? Like most of us, I have close friends who are battling cancer, and unfortunately, some who have lost this battle. More than a few have done their best to follow a keto diet in hopes that it will help to treat or at least slow down the progression of the disease.

Keto is short for ketogenic — a type of diet that has been used for over 100 years in children with uncontrolled seizures. This classic ketogenic therapeutic diet is a very-high-fat, extremely low-carbohydrate, lower-protein diet. Carbohydrates are typically our body’s main source of energy but because the ketogenic diet is so low in carbohydrates, fats become the primary fuel for the body. When we burn fat for energy, we produce compounds called ketone bodies – which is why it’s called the ketogenic diet.

Many people think they’re doing keto when they’re still eating plenty of protein-rich foods, which means they’re really just following a low carb diet. This can still be beneficial, but it’s not technically ‘keto.’

Although carbohydrate and protein limits can vary, the general rule of thumb for a keto diet is a maximum of 20 grams of carbohydrate daily or about 5% of total calories. Keto diets for cancer treatment are often lower, ranging from 5% to as low as 0.1% carbohydrate, with protein around 5-15%, and fat making up the rest, typically 80 to 90% or greater.

Explaining the Theory Behind the Keto Diet for Cancer Treatment 

The theory behind the keto diet as a treatment for cancer starts with the premise that our cells metabolize sugar for energy. So restricting sugar, or glucose, in theory, may help to starve cancer cells.

Research suggests that there might something to this theory. A promising study supports the idea that the keto diet could be used as a complementary approach to standard cancer therapies. Researchers from the University of Texas at Dallas restricted blood sugar levels in mice with lung cancer by giving them a ketogenic diet and also a diabetes drug that helped to reduce blood sugar levels. Both components of the study – diet as well as medication – showed potential benefits individually, and the combination of the two was even more effective.

“While these interventions did not shrink the squamous cell carcinoma tumors, they did keep them from progressing, which suggests this type of cancer might be vulnerable to glucose restriction,” said Dr. Jung-Whan “Jay” Kim, the corresponding author of the study and an assistant professor of biological sciences at UT Dallas.

The Science Behind the Keto Diet and Cancer Treatment

Director of the Sandra and Edward Meyer Cancer Center at Weill Cornell Medical College Dr. Lewis Cantley is a professor of cancer biology in medicine and a leading cancer researcher. Dr. Cantley discovered a critical enzyme called Pi3K that helped scientists understand the connection between cancer and insulin, and how cancer genes cause cancer in our bodies. He continues to study extensively on how the keto diet influences cancer cells.

All cells need glucose as a source of energy, and normal cells use mitochondria to convert glucose into energy. Cancer cells, however, use a different, and faster, process to metabolize sugar. In fact, glucose tests are commonly used to determine where tumors are located in the body. Glucose is labeled so that it can be detected on scans, then injected into the body where it goes straight to the site of the tumor because the cells are quite literally gobbling up the sugar.

So it makes sense that restricting cancer cells’ access to sugar may help cancer treatments be even more effective.

But as Dr. Cantley explains, a reduction in blood sugar is just one of at least five different ways that the keto diet may be effective in combating cancer, in conjunction with evidence-based treatment plans that often include some combination of chemotherapy, radiation therapy, and surgery:

1. Reduced blood glucose levels. Reducing the availability of circulating blood sugar means a reduction in the fuel source for cancer cells.
2. Reduced insulin levels. Insulin is an anabolic hormone – this means that it makes cells grow, including cancer cells. Lowering insulin levels can mean slower tumor growth.
3. Lower levels of IGF-1. Insulin-like growth factor 1, or IGF-1, is a hormone that is a protein growth signal for cancer. A lower-carb diet means lower levels of insulin, which means less IGF-1 and therefore potential for reduced cancer risk and reduced tumor growth.
4. Lower the tumor’s ability to produce VEG-F. VEG-F (vascular endothelial growth factor) is a protein that is involved in the growth of blood vessels to supply food and oxygen to tumors. Interfering with VEG-F means an interruption in the tumor blood supply.
5. Less visceral fat. This is the abdominal fat deep below the skin, stored around organs like the liver, intestines and pancreas. High amounts of visceral fat are linked to a host of health issues, including cancers like colorectal, postmenopausal breast cancer, pancreatic, uterine and esophageal cancer. Less visceral fat inherently lowers our risk for these types of cancers.

Why Keto Isn’t Standard Oncology Protocol (Yet)

The science seems so compelling that it’s easy to ask, “Why isn’t the keto diet part of standard cancer treatment?” Part of the answer lies in the fact that most research to date has been in animals and lab settings, not in humans. Multiple human studies are currently underway, but it will be several years before the findings from many of these are published.

“The keto diet is notoriously hard for many people to follow, even for those without cancer, and without solid evidence that there’s a real benefit, the benefits of prescribing the diet may not outweigh the potential downfalls,” said Dr. Elizabeth Lapeyre, a board-certified obstetrician and gynecologist with Ochsner Health in New Orleans who specializes in cancer survivorship. ”Many patients who follow a keto diet generally say they feel better, however, so I don’t rule it out as an option to complement traditional treatment,” Lapeyre said. “For those who chose to follow a keto diet, nutritional counseling with a dietitian is essential.”

Certain medications, as well as nausea from cancer treatments, can make it even more challenging to follow a strict ketogenic diet. Not to mention, food can be one of few sources of comfort, joy and familiarity to us during trying times. 

The keto diet is so limited in carbs, which means it’s also low in nutrient-rich whole grains, fruits, and even most vegetables – all of which are linked to a reduction in cancer risk. And as I’ve seen with friends and clients who’ve tried the diet, it can also be challenging to consume enough calories on a keto diet to keep weight on during cancer treatment.

Incorporating the Keto Diet A Part of Cancer Therapy

Targeting peoples’ glucose levels – or insulin or ketone levels – to inhibit the growth of cancer cells is a vastly different approach from trying to target cancer cells directly. The idea that we can work with our own systems, activating more of or dialing back on compounds that we already have in our bodies, is a fascinating complementary approach to cancer treatment.

Given the preliminary science, approaches like following the keto diet aren’t in any way intended to replace traditional therapies, but to accompanythem. While conventional treatments like surgery, chemotherapy and radiation are still the primary methods of treating tumors, science is exploring complementary treatments that may also help slow or stop the growth of cancer cells.

If you’re considering the keto diet or any other type of holistic, adjunct approach, always be open with your physician, registered dietitian and your entire oncology care team.

Ultimately, the best approach is to find a long-term plan that’s sustainable and not a ‘diet’ specifically. The keto diet may not be for you, but many of us can still benefit from dialing back our carbs and sugars. And we don’t have to strive for perfection; even the most moderate nutritional improvements can boost our whole-body wellness.

Editors note: This article was originally published on December 2, 2019. Be inspired to live your strongest, healthiest life! Subscribe to Molly's podcast FUELED | wellness + nutrition for the latest trends and research related to your body and mind.