Nutrition and Cancer: Does It Matter What Patients Eat During Treatment?

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The evidence that I looked at is clear; diet makes a big difference when patients are on chemotherapy and radiation

I see a lot of patients with cancer at my clinic. The vast majority tell me that their oncologist told them that it doesn’t matter what they eat during chemotherapy or radiation treatments. Some of these oncologists are so ingrained with this belief, and they give zero dietary advice because they are convinced that diet will not make a difference.

As a molecular biologist, I can make no sense of this rationale. During aggressive therapies such as chemotherapy and radiation, every cell in the body is under an enormous amount of stress. The metabolic demands on a patient’s cells are obviously increased so that they can survive in the presence of these toxins. If the metabolic demands are increased, then they clearly need nutrients to supply this demand. Since there is a big difference in the nutrient content of a Twinkie compared to an apple, logic dictates that this difference in nutrients would make a big difference when a patient’s cells are bathed in chemotherapy and radiation in an effort to kill cancer.

So this raises the question: Could the dietary advice of these oncologists be incorrect? They are very educated, and if they feel so passionately about role of diet (or lack thereof) in cancer then surely there must be a scientific reason for this. I decided to look at peer-reviewed research that studied how diets affected patients during chemotherapy and radiation.

Many studies have been done on humans and rats, which clearly show positive affects from diet during chemotherapy. When given a diet that is rich in nutrients, rats are able to tolerate significantly higher doses of chemotherapy and radiation.1,2  This is consistent with the ultimate goal of keeping cells strong so that chemotherapy can be better tolerated by the patient.

And then there’s the research done on fasting. One article in the journal The Oncologist explained the different mechanisms at work when caloric restriction enhances the effects of chemotherapy and radiation.3  The conclusion of their research is: “Caloric restriction by fasting is likely an effective method to potentiate the cytotoxicity of chemotherapy and radiation therapy because of the overlapping induction of molecular profiles, and it may also provide a beneficial means of improving the overall health and metabolic profiles of patients. At this time, clinical trials evaluating caloric restriction as a complementary therapy in the treatment of cancer are warranted.” Caloric restriction is a method where the patient maintains their nutrient status while decreasing the number of calories that they are ingesting. Pilot trials have been completed on the ketogenic diet and how it affects the quality of life in advanced cancer patients. The results clearly show that specific diets can improve quality of life in these patients.4

These are just a few examples of how different diets can impact one’s health during chemotherapy.

Diet alone is not a cure for cancer but when used properly it can help patients maintain their nutrient status during chemotherapy and radiation. I know that oncologists sincerely want the best for their patients and I have great respect for the work that they do. But I have come to the conclusion that their attitude about nutrition is not based on logic or scientific fact. The evidence that I looked at is clear; diet makes a big difference when patients are on chemotherapy and radiation. So in my opinion, oncologists who claim to be practising evidence-based medicine need to stop telling patients that it makes no difference, because this is not what the evidence shows. Oncologists do not get any training in nutrition and its role in cancer therapy. Their lack of training in nutrition becomes apparent when you consider their position on the subject despite the evidence showing that it can be an effective tool.6

The bottom line is that diet does make a difference as this is what the evidence shows. There is no question that a healthy balanced diet will make it easier for patients to tolerate chemotherapy and radiation. Even though many of these patients have low energy levels during chemotherapy, research indicates patients are willing and able to adhere to specific diets during chemotherapy.5 Anyone who eats a low quality diet will have lower energy and consequently a lower quality of life (recall the movie Supersize Me). This is common sense and this concept obviously applies to those who are undergoing chemotherapy and radiation.

It is not uncommon in my practice for patients to be going through chemotherapy and radiation with minimal side effects because they are nutritionally supported during this process. If you eat a high-quality diet under the supervision of a Naturopathic doctor (ND), then your cells with be better nourished to deal with the stresses of cancer and the aggressive treatments associated with cancer.


1)    Bounous G, Le Bel E, Shuster J, Gold P, Tahan WT, Bastin E. “Dietary protection during radiation therapy.” PubMed PMID: 807995.

2) Richard F. Branda, Zhuan Chen, Elice M. Brooks, Shelly J. Naud, Thomas D. Trainer, John J. McCormack, “Diet modulates the toxicity of cancer chemotherapy in rats,” Journal of Laboratory and Clinical Medicine, Volume 140, Issue 5, November 2002, Pages 358-368, ISSN 0022-2143.

3) Champ, Colin E., et al. “Nutrient restriction and radiation therapy for cancer treatment: when less is more.” The Oncologist 18.1 (2013): 97-103.

4) Schmidt, Melanie, et al. “Effects of a ketogenic diet on the quality of life in 16 patients with advanced cancer: A pilot trial.” Nutr Metab (Lond) 8.1 (2011): 54.

5) von Gruenigen, Vivian E., et al. “Feasibility of a lifestyle intervention for ovarian cancer patients receiving adjuvant chemotherapy.” Gynecologic oncology 122.2 (2011): 328-333.

6) Rock, C. L., Doyle, C., Demark-Wahnefried, W., Meyerhardt, J., Courneya, K. S., Schwartz, A. L., Bandera, E. V., Hamilton, K. K., Grant, B., McCullough, M., Byers, T. and Gansler, T. (2012), Nutrition and physical activity guidelines for cancer survivors. CA: A Cancer Journal for Clinicians, 62: 242–274. doi: 10.3322/caac.21142.

Dr. Adam McLeod is a former Naturopathic Doctor (ND) with a BSc. (Hon) in Molecular biology. He is also an International Best Selling Author.


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  1. C
    May 17, 19:42 Chris

    Very much appreciate your article …… great that you looked into the research on this …. it does seem like common sense to give the body the best nutritional basis possible for dealing with the extra stress of radiation + chemotherapy, but quite a few doctors I have encountered (in my family + among my circle of friends + acquaintances) simply have not been exposed to nutritional theories + information in their medical training.
    I assume + hope that this might be slowly changing ….. but unless an older doctor has developed a personal interest in nutrition, they might not know that much about it.

    In my humble opinion ….. based on growing up in a medical family + having heard the private opinions of many doctors from the 1950’s to 2018 ….. a doctor suggesting that it does not matter what one eats ….. cancer treatment or not …… is simply not very informed on the subject.

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  2. M
    July 18, 02:28 Michael N. Lumpkin

    Wonderful article. The importance of diet has been highlighted quite well here. Thanks Dr. Adam for posting this very informative article. And as you are a molecular biologist and a doctor yourself, not just people but even those who are in the field of medicine are more likely to trust you and your research. Hopefully, the oncologists ignorant of the importance of diet also come across this article and start advising patients on the benefits of diet.

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  3. C
    September 24, 20:53 Cody

    Great article! Food is medicine, Diet alone is not a cure for cancer but it sure helps heal the body.

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