Can a Low-Carbohydrate Diet Prevent or Treat Cancer?

Several lines of evidence point to the idea that restricting dietary carbohydrates may have beneficial effects in the prevention or treatment of cancer.

Cell cultures

Scientists often grow human or animal cells in lab dishes in order to study their reactions to various stimuli, such as nutrients or drugs. Cell cultures give us reliable information on how cells work, and their relative cheapness and short time frame of experiments make them a great resource, but since they don’t represent a whole organism animal or human, results must be cautiously interpreted.

In cell culture, increased uptake of sugar (glucose) increased important pathways linked to initiation of cancer and growth of cancer cells. Reduction of glucose uptake in cancer cells suppressed cancer-promoting pathways.

This makes sense due to the Warburg effect, which was discovered nearly 100 years ago by Otto Warburg. Cancer cells preferentially use glucose for energy in a process called anaerobic glycolysis. The PET scan, used to detect cancer, makes use of this effect by looking at tissues with increased glucose uptake, thus detecting cancer.

Curiously, Warburg’s original hypothesis that aerobic glycolysis itself could be the “origin of cancer cells” had not been proven directly. Our findings provide a hitherto-undescribed direct role of increased aerobic glycolysis in inducing the cancer phenotype, in which increased glycolytic activity regulates the canonical oncogenic pathways dynamically and reciprocally. These results may provide additional evidence for how hyperglycemia in diseases such as obesity and diabetes could provide a microenvironment that results in higher risk of some cancers. Additionally, our findings may explain how small molecules, such as metformin (used for treatment of diabetes and known to lower blood glucose levels), decrease the risk and mortality of several types of cancers. 


Animal studies

In mice, a low-carbohydrate, high-protein diet slows tumor growth and prevents cancer initiation. Mice that were implanted with tumor cells and fed the low-carbohydrate diet had slower tumor growth, and lower blood glucose and insulin. In mice bred for higher rates of spontaneous cancer, tumor incidence and insulin were lower on the low-carb diet.

Of interest, adding celecoxib, an anti-inflammatory drug, to a low-carbohydrate diet, markedly reduces metastasis. This may be for the same reasons that aspirin use is associated with less cancer.

A very low-carbohydrate ketogenic diet increases lifespan in mice. Among the changes noted in the mice fed the ketogenic diet was much lower tumor incidence; either the absence of carbohydrate in the diet, or the presence of ketones, meant less cancer.


Cancer has consistently been reported as rare to non-existent in peoples living in accordance with their traditional lifestyles, including Africans, American Indians, and Eskimos. Modern hunter-gatherer peoples eat far fewer carbohydrates, from 20 to 40% of calories, than do modern Americans, who eat 50% of calories as carbohydrates, on average. Hunter-gatherers also don’t eat highly processed carbohydrates, such as flour and sugar, which have been suggested to be uniquely involved in promoting cancer.

Insulin and IGF-1 (insulin-like growth factor) promote cancer, and a Western diet with high intake of refined carbohydrates, of the kind that promotes high blood sugar, in turn promotes insulin and IGF-1 signaling.

Obesity and diabetes are both associated with higher rates of cancer, and both obesity and diabetes are also associated with diets high in refined carbohydrates and sugar.

Thus, there are several reasons to think that a diet high in refined carbohydrates and/or sugar could promote cancer in humans.

Do low-carbohydrate (ketogenic) diets benefit cancer patients? This topic has engendered lots of controversy, with one side claiming that they could work wonders, the other side claiming a lack of solid evidence.

A review of human and animal studies on the ketogenic diet and cancer found:

The majority of animal studies (72%) yielded evidence for an anti-tumor effect of KDs. Evidential support for such effects in humans was weak and limited to individual cases, but a probabilistic argument shows that the available data strengthen the belief in the anti-tumor effect hypothesis at least for some individuals. Evidence for pro-tumor effects was lacking completely.

Good evidence in animal studies, weak evidence in humans, and no evidence of a pro-cancer effect.

Conclusion: A good case, but more evidence needed

If the reports of low to non-existent cancer among peoples living a traditional lifestyle without Western foods holds true, then that gives us reason to believe in the refined carbohydrate and cancer hypothesis. (I say “if”, because many of the reports are older and non-systematic, but still a phenomenon remarked upon by many doctors who lived among these peoples.)

Animal studies are another brick in the evidence wall, but of course rodents aren’t humans.

The fact that cancer cells feed on glucose, and that insulin promotes cancer growth, lead to the belief that cutting dietary carbohydrates can only help prevent or treat cancer. Certainly, there’s no evidence that cutting carbohydrates is harmful in that respect – or indeed, in any other respect.

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Leave a Comment:

Mary Rouche says February 18, 2018

I had no idea that I had type II diabetes. I was diagnosed at age 50, after complaining to my doctor about being very tired. There is no family history of this disease. I’m a male and at the time of diagnosis, I weighed about 215. (I’m 6’2″)Within 6 months, I had gained 30 to 35 pounds, and apparently the diabetes medicines (Actos and Glimiperide) are known to cause weight gain. I wish my doctor had mentioned that, so I could have monitored my weight more closely. I was also taking metformin 1000 mg twice daily December 2017 our family doctor started me on Green House Herbal Clinic Diabetes Disease Herbal mixture, 5 weeks into treatment I improved dramatically. At the end of the full treatment course, the disease is totally under control. No case blurred vision, frequent urination, or weakness
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BC says February 18, 2018

I wonder if some of the equivocal results in humans is due to the type of ketogenic diet, and suspect that too high protein intake (excess is converted to glucose which becomes food for cancer cells) would yield less than optical results. I think a KD that is mainly fat with carefully measured/monitored protein intake might yield the best cancer fighting results.

Drifter says February 19, 2018

This is a huge topic about which much could be said but two points to keep in mind. 1) The formal trials in hiumans AFAIK have ALL been in late stage patients with advanced cancer who failed conventional therapy. In other words the hardest of the hard cases, so to say that evidence is low, if evidence is based only on clinical trials, is not really meaningful. The best evidence would be likely to come from a thorough study of the individual patient outcomes from Doctors (e.g Winters and others) that have been actively applying metabolic therapies from the point on initial diagnosis. Additionally, much, perhaps most, of the benefit of metabolic therapies applies before a cancer would ever be detected, by increasing the body’s ability to eliminate early-stage cancers, so that would likely not be considered in current “evidence” either. And 2) all of the leading thinkers around optimizing ones metabolism to prevent cancer (e,g Seyfried, D’Agostino, Champ, Winters, and others) recommend other interventions in addition to diet and fasting, such as hyperbaric oxygen, intravenous vitamin C and various other things, as well as gradually introducing some conventional therapies in gradually increasing doses as needed when the cancer has been weakened by metabolic therapies. For example, Dr. Seyfried’s cancer cocktail being used in Turkey (apparently with good success) has four major components including diet/fasting, glycolysis inhibitors. hyperthermia, hyperbaric oxygen, and traditional chemo. This has apparently been successful even in late stage cancers, however per point one, Seyfried consistently emphasizes that prevention (he recommends fasting, another discussion for those of us who are already quite lean) is the best approach, which is a long way from being tested to the point of having mainstream “evidence”, so we’re going to have to do what seems best supported.

    P. D. Mangan says February 19, 2018

    I agree with all of that. In my article, I was mainly trying to avoid “ketogenic diet cures cancer – miracle cure” like I’m sure you’ve seen. I think cancer is a metabolic disease, prevention os best, and the ketogenic diet holds great promise.

      Drifter says February 19, 2018

      Yes, agree completely, and it’s unfortunate that things with a strong kernel of validity are often discredited by zealots who oversell them.

      Andy says April 8, 2018

      I did keto diet in June 2017 and lost weight quickly, blood sugars came down and a1c came down, but at the same time it was making me weak and sick. In 5 months on keto my life was turned upside down, I now walk with a kane. Biggest mistake of my life. My blood test shows my ferritin at 440, keto has to be responsible for it.

    Paul Rivas says February 20, 2018

    You make some very good points. It’s all about preventing the first inklings of cancer, which is why many of us use a vast array of supplements hoping for some kind of synergy. This is a frustrating process because there is no way to know for sure. We do know that inflammation and senescence play key roles in cancer development, so it’s a good idea to inhibit mTOR and reduce inflammation as much as possible.

Aboutlifting says February 22, 2018

Some studies suggest that cancer cells have the ability to change their metabolic pathway in case of lacking glocose…they would eat what is abundant. But it does make one wonder why people suddenly died of cancer one by one once sugar became mainstream..

Jean says February 23, 2018

Having read several articles similar to yours, when I was diagnosed with bowel cancer I immediately went on a ketogenic diet. I had been low carb for 7 years before that. I had part of the bowel removed, one lymph node had some cancer cells in it so was offered a 6 month course of chemotherapy. I maintained the ketogenic diet right through the course and the oncologists were impressed at how well I tolerated the chemo! I was subsequently scanned and tested and no cancer detected. Of course, this is just one case but how uplifting to have something that I could do to help myself! I am still ketogenic and hope not to have any recurrence – fingers crossed as well!

    P. D. Mangan says February 23, 2018

    Bravo, Jean, glad to hear of your success!

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