Improving Cancer Outcomes by Enhancing Gut Microbiome Health

Cancer is the second leading cause of death in the U.S., with one in four deaths being cancer related. While medical advances in surgery, chemotherapy, radiation, and immunotherapy have improved survivability by 26 percent since 1991, there is even more opportunity to improve quality of life and outcomes when the gut microbiome is considered in addition to traditional treatment. An integrative approach can prevent, halt, and reverse cancer cell growth, and while there are many factors to consider in cancer prevention and treatment, gastrointestinal (GI) health should always be addressed.

The development of cancer often takes years and no-doubt requires a variety of mechanisms for full-blown disease to occur. But, when it comes to the gut microbiome, pathogens, gut barrier and immune dysfunction, and microbial toxins have all been identified as triggers in the development of various cancers.

While more research is necessary, the gut microbiome indeed seems to be a significant contributor of cancer development in numerous ways. When creating a plan for those with cancer, it’s important to provide adequate fuel in the form of fiber and resistant starch, for the commensal bacteria to create SCFAs like butyrate. Butyrate supplies 70 percent of the energy needs for healthy colonocytes and may cause apoptosis in cancer cells. In addition, when digestible carbohydrates were replaced with resistant starch in mice with pancreatic cancer, tumor growth was slowed, and the microbiome was favorably altered. The lack of butyrate, on the other hand, has been shown to cause cancer cell proliferation.

Along with providing adequate fiber, cancer patients should limit dietary sugar intake since many cancers are known to thrive on glucose and glycolysis. I generally recommend patients obtain 40 percent of their calories from carbohydrates with limited to no intake of refined carbohydrates like breads, pastas, cereal- and gluten-containing grains, sugar in any form, and I encourage less than two servings of fruit per day.

Fasting is another strategy gaining traction for cancer prevention and therapy. As reported in Recent Results in Cancer Research, caloric restriction and various types of fasting have shown promise in preventing malignancy and can enhance traditional cancer therapies. It is well documented that cancer cells are susceptible to nutrient deprivation and targeting the metabolites and growth factors that fuel cancer cells with a fasting regimen can decrease their ability to adapt and survive during traditional cancer treatment. When humans are in the fasted state, glucose, insulin, leptin, and insulin growth factor-1 levels are low and glucagon, ketones, and adiponectin levels are high. Fasting essentially drives healthy cells into a mode that protects them from anticancer drugs while simultaneously increasing the sensitivity of cancer cells to those same drugs, thus serving as an adjunct to traditional cancer therapy. In addition, as previously stated, fasting has a positive effect on the gut microbiome.

While strict caloric restriction and water fasting have both shown positive effects when it comes to cancer treatment, they can also have detrimental consequences like severe weight loss and muscle wasting and they are difficult for patients to follow. Periodic fasting and the fasting mimicking diet (FMD), however, provide the valuable benefits of fasting without unfavorable effects and they are more easily implemented by cancer patients.

The FMD is a five-day vegan program that allows patients to consume food during the fast, but at a reduced calorie level. As reported in Nature Reviews. Cancer, the FMD does not result in the severe weight loss that is seen with strict caloric restriction and there are no adverse effects on the immune and endocrine systems. In addition, cancer patients can maintain their normal diet between FMD cycles allowing for more freedom with nutritional intake. In a small human trial of 34 participants with breast or ovarian cancer, use of the FMD for 36 to 48 hours before chemotherapy and lasting until 24 hours after chemotherapy resulted in maintained quality of life and reduced fatigue with no adverse effects.

Fasting and the FMD are not stand-alone therapies for cancer patients, but rather work in conjunction with traditional treatment to improve outcomes. Fasting and the FMD should not be recommended to those who are malnourished, frail, or at risk for malnutrition. It is crucial to provide adequate nutrients and if possible, encourage patients to participate in moderate physical activity to help maintain and/or increase muscle mass to maximize the effects of fasting and the FMD. In addition, it is suggested that patients wait a minimum of 24 hours between a single chemotherapy session and the resumption of the normal diet related to the regrowth signals of refeeding.

Editor’s Note: This is an excerpt from the e-book, Nutrition Foundations for the Gut Microbiome. To access the full text, click here.