Fasting and Keto to Improve Cancer Treatment, Reduce Side Effects?

Has fasting and the ketogenic diet gone mainstream in the treatment of cancer?

Does the early, published research support this novel approach as a plausible standard of care to complement and improve conventional therapy and reduce its often deleterious side effects?

Mainstreaming of Fasting and Keto for Cancer

CURE magazine bills itself as the largest-circulated consumer magazine in the U.S. dedicated to cancer survivors and their caregivers. Its latest cover story is titled Early Evidence Shows Fasting, Keto Diet May Make Chemo and Some Other Cancer Treatments More Effective and Easier to Tolerate.

It was remarkable to see such extensive coverage on lifestyle approaches that may improve certain cancer treatments and lower their toxicity, thereby helping mitigate some conventional treatment side effects.

What the animal-based (mice) research suggests:

  • Fasting decreases the toxicity of cancer treatments and may increase their efficacy.
  • A ketogenic diet, which deprives the body of carbohydrates, may increase the efficacy of certain cancer treatments.
  • Cancer cells and healthy cells respond differently to fasting. Healthy cells shut down their growth-promoting pathways soon after food intake stops, then shifts focus to cell repair.

What fasting does:

  • Depletes stored carbohydrates. Normal cells can adjust to this by running mostly on two fat-derived energy sources: fatty acids and ketones.
  • Deprives cancer cells of sugars, starches, and insulin that energize them.
  • Increases capacity for healthy cells to endure stressors such as chemotherapy or radiation therapy, while reducing nutritional support to tumors, therefore making them weak and vulnerable, with more difficulty to rapidly reproduce.

Most of the mouse studies to date have assessed fasting’s effect on chemotherapy or radiotherapy, but at least one study has found that a low-calorie fasting- mimicking diet (FMD) plus simple vitamin C can slow the progression of KRAS-mutated colon cancer.

[See Glenn Sabin’s Anticancer Foods List]

Another study, this one published in the prestigious journal Nature, found that both fasting and a FMD increased and extended the efficacy of the hormonal treatments tamoxifen and Faslodex (fulvestrant) in mouse models of hormone-receptor-positive breast cancer.

Fasting and Keto as Standard Care

Does the current body of literature support a ketogenic diet to complement standard cancer care? In a word, no. The body of evidence—peer-reviewed and published—neither irrefutably proves causality of fasting and keto to improve overall treatment outcomes, nor cites it as an effective tool to prevent the often deleterious symptoms of cancer therapies.

Immersed in this remarkable area of study, I’ve listened to the pioneer Dr. Thomas Seyfried lecture on ketogenics and fasting, followed the impressive work of Dr. Valter Longo, a top expert in the field, and taken an interest in the in-vivo animal research, including this systemic review and meta-analysis.

Roles of caloric restriction, ketogenic diet and intermittent fasting during initiation, progression and metastasis of cancer in animal models: a systematic review and meta-analysis

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I’ve now seen enough emerging data and shared clinical observations to unequivocally state: If I were to undergo active cancer treatment of any kind, I would not hesitate to incorporate a dairy-free, pescatarian keto-based diet with fasting.


Keto and Fasting is Not for Everyone

If you are dealing with a cancer challenge in the here and now—and about to undergo treatment; or in the middle of a treatment regimen—then you likely cannot wait for definitive published research proving the efficacy of keto and fasting.

If you are in a nutritionally sound place and healthy weight, and your oncologist and/or registered dietician clears you to fast, then I see no real downside as an adjuvant to standard therapy.

The reason for clearing it with your oncologist is because ketogenic diets and fasting are not for everyone: Cachexia is a wasting syndrome that can affect those with chronic illness; it typically includes weight loss, anorexia, asthenia, and anemia. Included in conditions that typify wasting is Sarcopenia, characterized by a decline of skeletal muscle and reduced muscle strength and physical performance.  All therapies involved in a healing journey must be considered by the team in order to consider outcomes and track efficacy.

I’ve had the same diet for over 25 years; written about it here. There are no plans to change it. For the past two years, intermittent fasting has been part of my life and I plan to continue to incorporate it. But implementing a 17-18 hour fasting routine was not implemented as an adjuvant to cancer therapy; it was for reasons such as weight management, shifting body composition, and to rest my digestive system—I simply feel more alert, energetic, and cognitively sharper as a result of intermittent fasting.

If I were ever to undergo standard cancer treatment, I would definitely apply keto and fasting, adjusting my current diet—a dairy-free pescatarian (cold water, high omega 3 fish such as salmon, cod, halibut, mackerel)—to a version of keto.  (Here’s an excellent article on pescatarian keto. There are dairy items listed as well—easily avoided.)

In Conclusion

Not surprisingly, companies are not throwing large sums of money at research projects that involve investigating diet and fasting as a preventative measure, as an adjuvant cancer therapy, or for cancer supportive care (ex., dietary and lifestyle approaches to reduce cancer therapy side effects). This is because these tend to not be easily patented and profitable commercialized products or services.

However, for those who are dealing with active cancer—not in a position to wait for published reviews—keto and fasting is a relatively low risk adjunct with the potential for measurable benefits. As long as you are healthy enough for the fasting aspect and get clearance from your oncologist, there is not much downside to incorporating this potentially potent lifestyle change while undergoing active cancer treatment.

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