The ketogenic diet has exploded in popularity over the last few years. Hordes of people are using it to lose body fat, overcome metabolic diseases, improve their endurance performance, attain steady energy levels, make their brain work better, and control seizures. And increasing numbers of researchers and personal experimenters are even exploring the utility of ketogenic diets in preventing and/or treating cancer. After all, back in the early part of the 20th century, Warburg discovered an important characteristic of most cancer cells: they generate their energy by burning glucose. If a particular cancer loves glucose, what happens if you reduce its presence in your body and start burning fat and ketones instead?
It’s taken a while, but the research community is finally beginning to take a few swings at this and similar questions.
So, what do we know?
First, let’s just go through a few recent human studies and case studies.
A Bayesian approach to studying the effects of ketogenic diets in humans and animals with high grade glioma (a brain cancer) found an “overall survival-prolonging effect.”
In gliomas, an analysis of available case studies using ketogenic diets found increased overall or progression-free survival. These were not randomized controlled trials, however, so they say nothing definitive.
A recent review paper gives a good overview of the current state of ketogenic diet and cancer research, finding that:
Ketosis targets tumor metabolism.
Ketosis improves effectiveness of conventional therapies.
Ketosis has favorable effects of anti-cancer gene expression.
One thing you might notice is that there are no studies showing that standalone ketogenic diets cure cancer. There aren’t very many randomized controlled trials in general.
What there are are studies showing that ketogenic diets are safe and potentially effective adjuvant treatments—treatments that supplement conventional cancer treatments. You don’t see keto “defeating” cancer alone. You see keto enhancing the effect of chemotherapy. You see keto enhancing the effect of radiation. You see keto protecting normal cells and increasing the vulnerability of cancer cells to conventional treatment.
That’s not to say that keto can’t beat cancer. Maybe it can. But the clinical research simply isn’t there to say one way or the other.
Where keto seems even more promising is in prevention of cancer.
Keto and Cancer Prevention
Diabetes is a disease of carbohydrate intolerance. It’s a disease in which carbohydrate consumption results in elevated blood sugar, exaggerated insulin response. The way most people with diabetes eat leads to chronically high levels of insulin and blood sugar. Yeah, yeah, I know about all the badass Primal eaters who are “technically” diabetic but keep their blood sugar pristine and insulin minimized by watching what they eat, exercising regularly, and just generally leading a healthy lifestyle—but those people aren’t a large enough a group to have an effect on the category known as (and studied as) “diabetics.” Most people with diabetes unfortunately keep eating the same junk that got them there.
What does research say about the cancer rate of most people with diabetes? It’s usually higher.
One of the most consistent risk factors for many types of cancer is having diabetes and experiencing all the metabolic fallout that entails—high fasting insulin, insulin resistance, elevated blood glucose. Cancers of the liver, pancreas, breast, endometrium, bladder, and kidney all have strong associations with type 2 diabetes. This should come as no surprise. Not only do many cancers thrive on glucose as fuel, the high insulin levels typical of people with diabetes and insulin resistance increase the availability of growth factors that promote cancer growth.
Meanwhile, therapies that are known to reduce the symptoms of diabetes—lower fasting insulin, increase insulin sensitivity, normalize blood sugar, etc—tend to lower the risk of cancer. A perfect example is metformin.
Metformin activates AMPK, the same autophagy pathway activated by exercise, fasting, polyphenol consumption, and reduced calorie intake. It lowers blood sugar, increases insulin sensitivity, and extends the lifespan of type 2 diabetics.
Now, not all cancers are linked to diabetes. For example, diabetes doesn’t increase the risk of gastric cancer. That’s because it’s linked to bacterial infection, not elevated blood sugar. And that’s why taking metformin doesn’t reduce the risk of gastric cancer. This actually supports my hypothesis that, when diabetes does not increase the risk of a cancer, neither does metformin reduce it—like gastric cancer. Diabetes doesn’t increase it, so metformin doesn’t reduce it. That’s the mechanism in play.
Nor do all cancers burn glucose exclusively. Some thrive in a ketogenic environment.
There is a mutation called BRAF V600E in certain cancer cells that allows them to utilize ketone bodies to stimulate growth. About 50% of melanoma, 10% of colorectal cancer, 100% of hairy cell leukemia, and 5% of multiple myeloma cases exhibit the ketone-utilizing BRAF V600E mutation. Indeed, a cancer cell’s inability to break down and metabolize ketone bodies is the best predictor of whether a ketogenic diet can even help against a given cancer.
But if we’re talking prevention. If we accept that not developing diabetes—all else being equal— probably reduces the risk of getting cancer, then using ketosis to improve all the same symptoms linked to diabetes should also reduce the risk of getting cancer. And if it doesn’t reduce the risk, it probably won’t hurt. I mean, is there a doctor alive who claims that increasing insulin sensitivity, lowering hyperinsulinemia, and losing body fat will increase the risk of cancer?
A Few Takeaways To Consider
As I see it—and this is not medical advice—the most promising use of ketogenic diets in cancer are as follows.
Adjuvant therapy: Using ketosis to enhance the efficacy of conventional therapies like chemotherapy and radiation, increasing the susceptibility of cancer cells to treatment and increasing survival of healthy host cells.
Prevention: Using ketosis (whether intermittently or long term) to lower fasting blood glucose, reduce diabetes risk (or resolve extant diabetes), and improve your ability to burn fat and not rely on exogenous glucose so much should in theory reduce your risk of most cancers.
Whatever you do, if you’re an actual cancer patient, discuss this with your doctor.Make sure your particular variety of cancer isn’t partial to ketones. Make sure it’s one of the cancers that actually craves glucose. If you end up with a cancer that thrives on ketone bodies, and you go deep into perpetual ketosis, you could be making an enormous mistake.
But the bottom line is that, assuming you don’t already have one of the cancers known to utilize ketones, going into ketosis from time to time isn’t going to hurt—and it will probably help reduce the risk of cancer.
I’m going to close this post with an anecdote from one of my employees. His father passed away a dozen years ago from multiple myeloma, a type of white blood cell cancer. This was before he worked at Primal Nutrition; he was just getting involved in alternative forms of health and nutrition research. What struck him most, particularly in retrospect, was how his father’s appetite changed during his battle with cancer. He began craving candy—Reese’s peanut butter cups, Hershey’s kisses, Now-and-Laters, and all other kinds. As he says it, looking at his dad’s snack drawer was like looking at the archetypal bag of Halloween candy.
I don’t know if this is evidence of anything. Can cancer actually tap into your specific appetites? Can it change how you perceive and desire specific foods? Was his father actually being programmed by his cancer to over-consume sugar?
What I do know is that no one needs garbage candy. A few seconds of momentary gustatory pleasure, followed by regret and the incessant need to repeat—is it worth it? Is it worth the off chance that eating lots of sugar feeds and promotes cancer? Don’t do it, folks. I know my longtime readers are right there with me. I know you guys who’ve been here from the beginning are probably getting egged on Halloween because you’re giving out collagen packets and mini-kettlebells. But if you’re new to this site and way of eating in general—maybe a co-worker passed my info along to you, maybe you’re trying to make a big change in the way you eat and live—avoiding the obviously terrible-for-you stuff like candy and baked goods is the biggest change you can make. And not just for cancer.
So, do I want you to walk away from this post thinking that keto is a cancer cure? No. I’m a fan of ketosis, and I think almost everyone should spend time in that metabolic state, but I don’t consider it to be magical. The jury is definitely still out. Does ketosis look like a strong candidate for improving efficacy of various therapies in certain cancer patients? Yes. Can keto improve health markers shown to reduce a person’s risk of getting cancer in the first place? Yes.
The keys to good health are generally speaking pretty consistent.
Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.