Diets and Metabolic Therapies: Introduction

What are these therapies?

Several types of diets and metabolic therapies are available:

• Diets generally recommended for reducing risk of cancer or recurrence
• Diets used as treatments for some types of cancer
• Diets or approaches such as fasting used to alter your metabolism

What are the benefits of using these therapies?

Many people with cancer make improving their diet a part of their treatment approach, and with good reason. Good evidence shows that what you eat can reduce your risks of cancer or recurrence. Your diet can also help you manage side effects and symptoms throughout your cancer experience. 

Following an individualized, health-supportive eating plan together with your primary treatment is a good idea. The American Institute for Cancer Research has concluded that a plant-based, whole-foods diet is the most prudent dietary pattern to adopt for reducing the risks of cancer and possibly cancer recurrence.¹American Institute for Cancer Research. Cancer Prevention Recommendations. From World Cancer Research Fund/American Institute for Cancer Research. Diet, Nutrition, Physical Activity and Cancer: A global Perspective.Continuous Update Project Expert Report 2018. Viewed January 6, 2022.

Much less evidence supports using specific diets for cancer treatment. Although a few diets have shown benefit, others show little or no benefit or may even be harmful. 

Metabolic therapies aim to control or alter cancer’s growth by changing your metabolism. These approaches include fasting and a ketogenic diet.

Are they safe?

Consult your healthcare team about any dietary changes you are making or considering, especially if you are dealing with changes in your appetite, digestive function, or body weight, or if your cancer directly affects your digestive system. If you need additional support, consult a certified oncology dietician nutritionist. You can ask your physician for a referral.

Browse diets and metabolic therapies

Upcoming reviews

While we create reviews for each of these specific diets, we share brief assessments.

• Alkaline diet: The American Institute for Cancer Research has concluded that the acidity or alkalinity of foods is not important, but some oncologists find that acidosis is associated with impaired immunity, reduced glutathione and reduced insulin sensitivity—all body terrainthe internal conditions of your body, including nutritional status, fitness, blood sugar balance, hormone balance, inflammation and more factors connected to cancer. The alkalinity of foods can contribute to acidosis: “A diet rich in fruits and vegetables and low in animal protein and sodium chloride [salt] reduces acid load.”²Pizzorno J. Acidosis: an old idea validated by new research. Integrative Medicine (Encinitas). 2015 Feb;14(1):8-12.
• Gerson diet: A review of evidence regarding this approach along with other cancer therapies or as a cure did not find convincing evidence of benefit.
• Gonzalez diet: A small study of people with pancreatic cancer—typically with very poor survival—found substantially longer survival on this diet, although this finding was not repeated in a much larger study with some serious design flaws.
• Intermittent fasting: Not only what you eat but when you eat can affect your health. Regularly restricting or eliminating food intake for several hours or longer can lower insulin resistance, improve your response to chemotherapy, and reduce some side effects of cancer treatments. It may also reduce your risk of recurrence.
• Living foods diet (raw foods diet): A review did not find clinical evidence of benefit from a living foods diet among people with cancer.
• Macrobiotic diet: This approach based on a traditional Japanese diet has been supported by a few reports of people claiming remarkable reversal of their cancer, but evidence to date does not support the use of this diet for reducing cancer risk or improving survival or quality of life.
• Paleolithic (Paleo) diet: This diet is linked to lower mortality either from cancer or from all causes, and also with lower risk of colorectal adenomas.
• Vegan diet: A vegan diet was linked to a 15% lower incidence of total cancer in a combined analysis of several studies.