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Diet, Cancer and Chemotherapy

Updated: May 13, 2021

How the work of Dr Valter Longo may dramatically improve the experience of at least some patients undergoing chemotherapy.

It’s almost exactly a year since my partner was diagnosed with breast cancer. She had a mastectomy in January 2019 and shortly after that began 6 months of chemotherapy. What I most wish today is that I’d discovered the work of Dr Valter Longo before she had to endure that, but as so often is the case we only really start preparing for things after they’ve happened.

I came across Dr Longo’s work by chance. An offhand comment in a conversation about read an article ( by Decca Aitkenhead in which she talks about her own experience with breast cancer and its treatment. Her experience with her first round of chemo exactly mirrored that of my partner. We spent a few hours sitting in the hospital while they slowly pushed the drugs into her and then went home. The next day things seemed ok and we went for a short walk and she began to feel a bit ill. By the evening she was being sick and stayed that way for most of the next week. While my partner did that every three weeks for most of the next six months, Decca Aitkenhead describes a very different experience. Prior to her second round of chemotherapy she ate nothing for 72 hours and then didn’t eat for a further 24 hours afterwards and the sickness just didn’t come. The course of chemo was still debilitating, you can’t add that much toxicity to your body and not feel it’s effect, but the immediate aftermath of each round was eliminated. I had to know more.

Dr Valter Longo is a scientist specialising in cellular biology and the biology of aging. His work began with laboratory work on yeasts looking to understand the process of aging within simple single celled organism and it was here that he first made the connection between restricting food intake and longevity. He went on to work on mice and it was here that he discovered that periods of severe fasting significantly increased the efficacy of chemotherapy. For example, among mice with a highly aggressive type of cancer, 20% of those in which the cancer had fully spread, and 40% with a more limited spread, were completely cured after fasting in conjunction with chemotherapy. In neither case did a single mouse treated with chemotherapy alone survive. Reproducing this work in clinical trials has been harder, not because of a lack of efficacy but because the medical establishment was reluctant to take his work seriously. When he did eventually get a small number of patients and their oncologists signed up to a preliminary study it took years to complete, in part because the patients often found fasting for 96 hours impossible. It was this difficulty and the fact that oncologists aren’t that keen on their patients going without food for so long that led Dr Longo to develop what he calls the fasting mimicking diet, a diet that allows patients to eat while offering the benefits of fasting.

For cancer patients undergoing chemotherapy fasting offers very specific benefits. After about 36 hours the body switches from utilising glucose to feeding from its fat reserves, a state known as ketosis. In this state cells in the body are somewhat stressed and go into a protective state and so are less susceptible to the toxic effects of the chemotherapy. However the cancer cells are still trying utilise glucose and so lack this protection leading, Dr Longo asserts, to chemotherapy having less side effects and greater efficacy. But it’s not just cancer patients who might benefit from periodic fasting of this sort. Dr Longo suggests that it might provide all of us with a number of health benefits as well as serving to reduce risk factors for some of the diseases common to affluent westerners; diabetes, coronary heart disease and auto-immune conditions. These benefits seem to derive from a general reduction in body fat, particularly visceral fat, better tolerance to insulin, and the effects of autophagy. Autophagy is a condition in which the body consumes its own tissues. It doesn’t sound great until one understands that the body eats damaged tissues first and Longo suggests this process is going on at the cellular level where, for instance, damaged proteins are reabsorbed. During fasting the body also seems to produce more stem cells leading to rapid rebuilding once feeding is resumed and so the fasting provides, or perhaps augments, a renewal mechanism for the body.

Dr Longo’s work on cancer is perhaps more developed than his work on other conditions and throughout his book ‘The Longevity Diet’ he repeatedly warns against using his findings about particular diseases outside of clinical trials. However much of the book is concerned with longevity more generally and the role diet plays. Here he leans not just on his own laboratory work, but also on clinical trials, epidemiological studies and his own research into cultures and communities where there’s an abnormally high percentage of centenarians. He’s used this work to develop what he calls the longevity die, its low in protein, low in animal fat and high in vegetables. What separates this from other diet books is the rigorous approach he takes to assembling the evidence from a variety of sources prior to making a recommendation. Having seen cancer up close and personal over the past year I’m certainly going to be adopting some of his recommendations and attempting a few five days fasts where I shall be cheating and actually eating thanks to Dr Longo’s Fast Mimicking Diet.


Bruce Bell is a fully trained 5 Element Acupuncturist working in the Midsomer Norton / Radstock area, and also from a clinic on the edge of Bath.

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