Fasting and Chemotherapy: Increase Efficacy, Reduce Side Effects

A Functional Guide to Supporting Cancer Patients

Chemotherapy can be life-saving, but for many patients, its side effects can feel overwhelming. The toll on the body is significant, from nausea and fatigue to long-term health impacts. What if there was a way to make chemotherapy more effective and tolerable? Fasting is a practice that is gaining attention due to its potential to enhance chemotherapy's efficacy while reducing its adverse effects.

QUICK REFERENCE

• A Functional Guide to Supporting Cancer Patients
• What Does the Research Say?
• The Science Behind Fasting and Chemotherapy: A Two-Fold Protection
• Deep Dive: Autophagy and Mitochondrial Function
• Additional Research Findings: Human vs. Animal Studies
• Human Pilots Studies: Why They Matter
• Human Case Study Series
• Clinical and Patient Experience
• How Fasting Can Support Chemotherapy Patients: Practical Benefits
• Risks and Considerations
• Role of the Oncology Nutrition Consultant
• Personalized Fasting Protocols
• Nutritional Support During Non-Fasting Periods
• A Patient-Centric Approach: How to Fast Safely Around Chemotherapy
• Combination Therapies: Fasting and Beyond
• Myths vs. Facts About Fasting and Chemo
• Is Fasting Right for You?
• FAQs
• Discussion

What Does the Research Say?

Recent studies suggest fasting for short periods surrounding chemotherapy treatments can improve outcomes in cancer patients. This approach, known as "short-term fasting," leverages the body's natural protective mechanisms to bolster healthy cells while making cancer cells more vulnerable to treatment. (1)

Key Findings:

• Fasting 24-36 hours before and after chemotherapy makes cancer cells more sensitive to treatment. The body's healthy cells become more resistant to the toxic effects of chemotherapy, reducing side effects like nausea and fatigue.
• Animal studies have shown that short-term fasting can slow tumor growth, sometimes as effectively as chemotherapy drugs alone. When combined with chemotherapy, fasting has been shown to shrink tumors even further.
• Human pilot studies suggest that fasting can reduce the blood toxicity of chemotherapy, speed up recovery, and potentially lessen the suppression of bone marrow, which is critical for maintaining immunity during treatment.

The Science Behind Fasting and Chemotherapy: A Two-Fold Protection

Chemotherapy targets rapidly dividing cells—a hallmark of cancer. Unfortunately, it also attacks healthy cells that divide quickly, such as those in the digestive tract, hair follicles, and bone marrow, leading to various side effects. Fasting shifts the body's energy metabolism and triggers a "protective mode," wherein healthy cells slow their division and bolster their defense mechanisms. (2)

Here's What Happens:

1. Cancer Cells Become More Vulnerable: Fasting inhibits the cancer cell's ability to produce protective proteins, making them more susceptible to chemotherapy.
2. Healthy Cells Become More Resistant: Healthy cells increase the production of protective proteins and reduce their division rate, minimizing chemotherapy's impact.
3. Fasting Reduces IGF-1 Levels: Insulin-like Growth Factor 1 (IGF-1) is a critical hormone that promotes cell growth. High levels of IGF-1 are associated with cancer progression, but fasting lowers IGF-1 levels, further protecting healthy cells while depriving cancer cells of growth signals. (3, 4)

Deep Dive: Autophagy and Mitochondrial Function

When fasting, the body enters autophagy, a natural process that helps clear damaged cells and regenerate healthier ones. Autophagy is critical in cancer treatment because it can help remove potentially harmful or cancerous cells while supporting the body's resilience to chemotherapy. (5) This is particularly important for mitochondria, the powerhouses of cells, which play a pivotal role in how cancerous and healthy cells respond to stress. (6)

Fasting improves mitochondrial function by reducing oxidative stress and inflammation. In healthy cells, fasting gives the mitochondria a break, allowing them to repair themselves and increase their resistance to chemotherapy. Meanwhile, cancer cells, which rely heavily on abnormal energy production pathways, struggle to adapt during fasting, making them more likely to be damaged by the chemotherapy drugs. (7)

Additional Research Findings: Human vs. Animal Studies

A deeper look into the differences between human and animal studies on fasting and chemotherapy helps us understand the broader implications of this practice and where the research might lead next.

Animal Studies: What We've Learned So Far

A 2012 study by Dr. Valter Longo and colleagues at the University of Southern California examined the effects of short-term fasting in mice implanted with breast cancer, melanoma, or glioma cells.

Results Showed:

• Short-term fasting (24-36 hours) alone delayed tumor growth to a similar extent as chemotherapy.
• Fasting stopped cancer cells from producing protective proteins from their mutated genes, while healthy cells made more protective proteins. As a result, side effects decreased as the healthy cells stopped dividing and were less attacked by the chemotherapy.
• When fasting was combined with chemotherapy drugs like doxorubicin or cyclophosphamide, tumors in fasting mice shrank to less than half the size of those in mice that received chemotherapy alone. (8)

However, while these results are promising, it's essential to recognize the limitations of animal studies. Mice, for example, have much faster metabolic rates and different cellular processes than humans, so translating these findings into human treatments requires careful analysis. Animal models give us an early glimpse into the mechanisms at play. Still, they can't capture human biology's complexity nor reflect individual variability in cancer types, stages, or patient health conditions.

Human Pilots Studies: Why They Matter

Human studies on fasting and chemotherapy, like the 2015 pilot study in breast cancer patients, are smaller and more cautious due to ethical concerns and the potential risks of fasting. These early-stage trials help researchers evaluate the safety and feasibility of fasting before more extensive, more definitive studies can be conducted.

In this study, seven out of 13 patients with HER2-negative stage II/III breast cancer on (neo)-adjuvant TAC (docetaxel/doxorubicin/cyclophosphamide) were randomized to fast 24 hours before and 24 hours after chemotherapy. Those fasting could only have water, coffee, or tea with no other added ingredients.

The Study Found:

• Fasting reduced hematological toxicity, meaning less damage to blood cells, from chemotherapy.
• Higher red blood cell and platelet levels indicate faster recovery from DNA damage and less suppression of bone marrow activity.
• The fasting group reported fewer side effects like nausea, diarrhea, and fatigue. (3)

The findings are promising, but more extensive randomized clinical trials are needed to confirm these results across a more diverse patient population and different types of cancer.

A review of short-term fasting and fasting-mimicking diets combined with chemotherapy found nine additional pilot studies investigating different types of cancers, including lung, ovarian, prostate, and colorectal cancer. Researchers are looking for the pathological response, quality of life assessments, optimal fasting duration, and how it impacts specific side effects at different grades and stages. (9)

Researchers must also weigh the potential benefits of fasting against the risks, such as malnutrition or dehydration, which can be particularly dangerous in cancer patients already facing compromised immune systems and nutrient deficiencies.

Human Case Study Series

In 2009, a case series was published in Aging, documenting ten cancer patients who followed a water-only fast before and after chemotherapy. The fasting period ranged from 48 hours to 140 hours before chemotherapy and from 5 hours to 56 hours after chemotherapy.

Key Outcomes Included:

• All ten patients reported significant reductions in nausea, vomiting, and fatigue during chemotherapy cycles when they had fasted.
• Four patients who fasted throughout their treatment experienced a lower severity of side effects compared to those who did not fast. (10)
• The mechanism may involve reducing growth factors, anabolic hormones, and mitogenic hormones.

Clinical and Patient Experience

In addition to clinical studies, Clinician and patient experiences and testimonials provide potent insights into the benefits of fasting.

I have seen a profound difference in improved tolerance among my clients when they can adhere to a fasting schedule around their chemotherapy infusions, and many of them fare pretty well in terms of outcome.

While anecdotal, my and my client’s experiences align with similar reports from patients who have tried fasting. Such testimonials can guide individuals considering fasting, helping them feel more confident and informed about their choices.

How Fasting Can Support Chemotherapy Patients: Practical Benefits

Here's a quick summary of the key benefits that fasting can offer during chemotherapy, according to current research:

• Increased Sensitivity: Cancer cells become more susceptible to chemotherapy, potentially making treatments more effective.
• Reduced Side Effects: The severity of common side effects, including nausea, vomiting, diarrhea, and fatigue, is reduced.
• Enhanced Recovery: After treatment, patients rebound faster, particularly in higher blood cell counts and less bone marrow suppression.
• Decreased Toxicity: Healthy tissues have decreased toxicity, including protection from DNA damage and reduced organ stress.

Risks and Considerations

While the benefits of fasting are encouraging, it's essential to approach it cautiously, especially during cancer treatment. Not every patient will be a good candidate for fasting, and it's critical to consider the risks involved. (2)

Who Should Be Cautious?

• Elderly or underweight patients may struggle to maintain their energy levels during fasting. For these individuals, the risk of malnutrition may outweigh the benefits.
• Patients with diabetes or other blood sugar regulation issues need to be particularly cautious, as fasting can lead to dangerously low blood sugar levels.
• Those undergoing high-dose chemotherapy or with advanced cancer may be at greater risk for complications from fasting, as their bodies are already under significant stress.

Potential Complications

• Dehydration is a common concern during fasting, especially in patients already at risk due to chemotherapy. Drinking plenty of water and managing electrolyte balance is critical.
• Low blood sugar can lead to dizziness, fatigue, or even fainting, particularly in patients already weakened by their treatment. A modified fasting regimen that includes light nourishment may be necessary for these patients.

Role of the Oncology Nutrition Consultant

Patients interested in fasting must work closely with an oncology nutrition consultant or practitioner trained in the metabolic approach to cancer to ensure the fasting process is safe and effective. A nutritionist can provide personalized advice tailored to each patient's unique health status, treatment plan, and lifestyle.

Personalized Fasting Protocols

A thorough assessment of the patient's overall health and creating a customized fasting plan that fits their needs can help mitigate risks. Including shorter fasting windows (12-16 hours) for those new to fasting or longer fasts (up to 36 hours) for those who tolerate it. The patient's response to fasting is closely monitored, and adjustments are made as needed. (11)

Nutritional Support During Non-Fasting Periods

What a patient eats between fasting periods is as important as the fast. It's highly recommended that patients consume nutrient-dense, anti-inflammatory foods that support the body's healing processes and help replenish depleted nutrient stores. Foods rich in antioxidants, lean proteins, and healthy fats are ideal for promoting recovery.

A Patient-Centric Approach: How to Fast Safely Around Chemotherapy

While the research is promising, fasting is not for everyone, especially those undergoing chemotherapy. Patients considering fasting should always consult their oncologist and a nutrition professional before making any changes to their treatment plan. Here are some critical guidelines for those interested in giving it a try:

• Start Small: Begin with shorter fasting periods (12-24 hours) before and after chemotherapy, gradually increasing the duration as tolerated.
• Stay Hydrated: Drink plenty of water, herbal teas, or black coffee during fasting. Electrolyte balance is crucial, especially when fasting for extended periods.
• Listen to Your Body: Fasting should not lead to extreme discomfort or fatigue. Patients should pay attention to how their body responds and adjust accordingly.

Combination Therapies: Fasting and Beyond

One exciting area of research is combining fasting with other cancer treatments, such as immunotherapy or radiation therapy. Preliminary studies suggest that fasting may enhance the effects of these treatments by improving the immune system's ability to target cancer cells and reducing radiation damage to healthy tissue. (12)

As more extensive clinical trials are conducted, fasting may one day become a standard part of cancer treatment protocols. However, more research is needed to identify the best fasting strategies for different cancers, patient populations, and chemotherapy regimens.

Myths vs. Facts About Fasting and Chemo

Fasting during chemotherapy can seem daunting, and a couple of myths may deter patients from trying it. Let's clear up some common misconceptions:

Myth: "Fasting will weaken me and make me less able to tolerate treatment."

Fact: As demonstrated earlier, short-term fasting has been shown to protect healthy cells and reduce side effects. Many patients report feeling better and recovering faster from chemotherapy. An individualized fasting and nutritional support plan will likely yield better outcomes than skipping breakfast before your first treatment. I don't recommend this strategy!

Myth: "I can't fast because I'll become malnourished."

Fact: While fasting for prolonged periods can cause malnutrition and might not benefit all patients, medically supervised short-term fasting is generally safe and may enhance your body's response to chemotherapy.

Is Fasting Right for You?

Fasting offers exciting potential as an adjuvant for chemotherapy, enhancing its efficacy and reducing side effects. Still, as with most areas of cancer care, it's not a one-size-fits-all solution. (13) If you're considering fasting, it's essential to consult with your healthcare team, including your oncologist and a functional nutritionist, to develop a personalized plan that meets your unique needs.

Fasting could be a powerful tool in your cancer treatment journey if you carefully balance the risks and benefits. With more research on the horizon, the future of fasting in cancer care looks promising. The key is staying informed, listening to your body, and working closely with your healthcare team to find your best approach.

FAQs

References:

1. de Groot S, Pijl H, van der Hoeven JJM, Kroep JR. Effects of short-term fasting on cancer treatment. J Exp Clin Cancer Res 2019;38:209. doi: 10.1186/s13046-019-1189-9.
2. Ferro Y, Maurotti S, Tarsitano MG, Lodari O, Pujia R, Mazza E, et al. Therapeutic Fasting in Reducing Chemotherapy Side Effects in Cancer Patients: A Systematic Review and Meta-Analysis. Nutrients. 2023 Jun 8;15(12):2666. doi: 10.3390/nu15122666.
3. de Groot S, Vreeswijk MP, Welters MJ, Gravesteijn G, Boei JJWA, Jochems A, et al. The effects of short-term fasting on tolerance to (neo) adjuvant chemotherapy in HER2-negative breast cancer patients: a randomized pilot study. BMC Cancer. 2015;15:652. doi: 10.1186/s12885-015-1663-5.
4. Koppold-Liebscher D, Kessler CS, Steckhan N, Bähr V, Kempter C, Wischnewsky M, et al. Short-term fasting accompanying chemotherapy as a supportive therapy in gynecological cancer: protocol for a multicenter randomized controlled clinical trial. Trials. 2020;21:854. doi: 10.1186/s13063-020-04700-9.
5. Caccialanza R, Cereda E, De Lorenzo F, Farina G, Pedrazzoli P; AIOM-SINPE-FAVO Working Group. To fast, or not to fast before chemotherapy, that is the question. BMC Cancer. 2018 Mar 27;18(1):337. doi: 10.1186/s12885-018-4245-5.
6. Antunes F, Erustes AG, Costa AJ, Nascimento AC, Bincoletto C, Ureshino RP, et al. Autophagy and intermittent fasting: the connection for cancer therapy? Clinics (Sao Paulo). 2018 Dec 10;73(suppl 1):e814s. doi: 10.6061/clinics/2018/e814s.
7. Nencioni A, Caffa I, Cortellino S, Longo VD. Fasting and cancer: molecular mechanisms and clinical application. Nat Rev Cancer. 2018 Nov;18(11):707-719. doi: 10.1038/s41568-018-0061-0.
8. Lee C, Raffaghello L, Brandhorst S, Safdie FM, Bianchi G, Martin-Montalvo A, et al. Fasting cycles retard growth of tumors and sensitize a range of cancer cell types to chemotherapy. Sci Transl Med. 2012 Mar 7;4(124):124ra27. doi: 10.1126/scitranslmed.3003293.
9. Kikomeko J, Schutte T, van Velzen MJM, Seefat R, van Laarhoven HWM. Short-term fasting and fasting mimicking diets combined with chemotherapy: a narrative review. Ther Adv Med Oncol. 2023 Mar 22;15:17588359231161418. doi: 10.1177/17588359231161418.
10. Safdie FM, Dorff T, Quinn D, Fontana L, Wei M, Lee C, et al. Fasting and cancer treatment in humans: A case series report. Aging (Albany NY). 2009 Dec 31; 1:988-1007 . doi: 10.18632/aging.100114.
11. Thompson S, Madsen LT, Bazzell A. Impact of Fasting on Patients With Cancer: An Integrative Review. J Adv Pract Oncol. 2023 Nov;14(7):608-619. doi: 10.6004/jadpro.2023.14.7.5.
12. de Gruil N, Pijl H, van der Burg SH, Kroep JR. Short-Term Fasting Synergizes with Solid Cancer Therapy by Boosting Antitumor Immunity. Cancers (Basel). 2022 Mar 9;14(6):1390. doi: 10.3390/cancers14061390.
13. Elkefi S, Asan O. The Impact of Patient-Centered Care on Cancer Patients' QOC, Self-Efficacy, and Trust Towards Doctors: Analysis of a National Survey. J Patient Exp. 2023 Jan 17;10:23743735231151533. doi: 10.1177/23743735231151533.