Does sugar feed cancer?

Sugar does not directly feed cancer in the way the internet often claims, but it does indirectly. High blood sugar drives high insulin and high IGF-1, both of which promote cancer cell growth and survival. Lowering refined sugar and refined carbohydrates reduces those signals. The right framing is not "sugar causes cancer" but "chronic high insulin makes a tumors environment more favorable."

Can I do high-dose IV vitamin C alongside chemotherapy?

Yes, high-dose IV vitamin C is a common and well-studied integrative oncology adjunct, but timing matters. At pharmacologic doses (25 to 100 grams IV), vitamin C acts as a pro-oxidant that can selectively damage cancer cells. It is generally given on non-chemo days to avoid interfering with the oxidative mechanism of certain chemotherapies. Always coordinate with your oncology team.

Can melatonin help during cancer treatment?

Yes, melatonin has reasonable evidence as an adjunct in cancer care. Multiple meta-analyses show that high-dose melatonin (often 10 to 20 milligrams nightly) added to standard treatment may improve survival, reduce side effects, and help with sleep. It is generally well tolerated and inexpensive. We dose it based on your specific cancer type and oncologists input.

Should I worry about specific blood markers during treatment?

Yes. We watch lymphocyte counts (immune function), albumin (nutrition status), ferritin (inflammation), CRP (systemic inflammation), vitamin D (immune and outcome marker), glucose and insulin (metabolic environment), and HbA1c. Trends matter more than single readings. We aim to keep nutrition and immunity strong without interfering with the oncology plan.

Can integrative care help with chemotherapy side effects?

Yes, integrative care can meaningfully reduce common chemo side effects. Ginger and acupuncture help with nausea. Exercise reduces fatigue. Glutamine helps with mouth sores. Omega-3s preserve muscle. Melatonin and acupuncture help with sleep. The right combination depends on the chemo regimen and the patient. We tailor a plan cycle by cycle.

Does sugar feed cancer?

Sugar does not directly feed cancer in the way the internet often claims, but it does indirectly. High blood sugar drives high insulin and high IGF-1, both of which promote cancer cell growth and survival. Lowering refined sugar and refined carbohydrates reduces those signals. The right framing is not "sugar causes cancer" but "chronic high insulin makes a tumors environment more favorable."

Can I do high-dose IV vitamin C alongside chemotherapy?

Yes, high-dose IV vitamin C is a common and well-studied integrative oncology adjunct, but timing matters. At pharmacologic doses (25 to 100 grams IV), vitamin C acts as a pro-oxidant that can selectively damage cancer cells. It is generally given on non-chemo days to avoid interfering with the oxidative mechanism of certain chemotherapies. Always coordinate with your oncology team.

Can melatonin help during cancer treatment?

Yes, melatonin has reasonable evidence as an adjunct in cancer care. Multiple meta-analyses show that high-dose melatonin (often 10 to 20 milligrams nightly) added to standard treatment may improve survival, reduce side effects, and help with sleep. It is generally well tolerated and inexpensive. We dose it based on your specific cancer type and oncologists input.

Should I worry about specific blood markers during treatment?

Yes. We watch lymphocyte counts (immune function), albumin (nutrition status), ferritin (inflammation), CRP (systemic inflammation), vitamin D (immune and outcome marker), glucose and insulin (metabolic environment), and HbA1c. Trends matter more than single readings. We aim to keep nutrition and immunity strong without interfering with the oncology plan.

Can integrative care help with chemotherapy side effects?

Yes, integrative care can meaningfully reduce common chemo side effects. Ginger and acupuncture help with nausea. Exercise reduces fatigue. Glutamine helps with mouth sores. Omega-3s preserve muscle. Melatonin and acupuncture help with sleep. The right combination depends on the chemo regimen and the patient. We tailor a plan cycle by cycle.

TL;DR · 30-second take

Integrative cancer care adds metabolic and lifestyle therapies (fasting, exercise, targeted supplements, sleep optimization) to standard oncology treatment. The goal is to support the patient and weaken the tumors metabolic flexibility, while always working with (not replacing) your oncologists plan.

Integrative Cancer Care: The Metabolic Adjunct

What is integrative cancer care, and how is it different from "alternative" cancer care?

Integrative cancer care adds evidence-based metabolic and lifestyle therapies to standard oncology, not in place of it. Standard treatment (chemotherapy, radiation, immunotherapy, surgery) damages the tumors DNA. Integrative oncology, sometimes called Medicine 3.0, focuses on the tumors metabolism, the patients resilience, and recovery between treatments. Cancer cells are metabolically inflexible. They depend heavily on glucose (the Warburg effect, first described by Otto Warburg in the 1920s) and growth factors like IGF-1 to survive. Healthy cells are far more flexible. They can switch to running on ketones during a fast. That biological difference opens what oncology researchers call a "therapeutic window." Tools like fasting-mimicking diets (FMDs) and select metabolic therapies, used alongside chemotherapy under medical supervision, may weaken cancer cells while protecting healthy ones.

Important: Integrative care is not a replacement for oncology. It is an adjunct. Always work with your oncologist before making any changes during active treatment.

What does the research say about fasting and chemotherapy?

Dr. Valter Longo's lab at USC pioneered the science showing that short-term fasting can protect healthy cells from chemotherapy toxicity, an effect called "differential stress resistance."² The key idea: chemotherapy attacks fast-dividing cells (hair follicles, gut lining, bone marrow). Longo's research found that when mice and humans fasted before chemo:

Healthy cells detected the lack of food, dropped into a "shield mode," and shut down growth pathways to conserve energy. The chemo had less effect on them.
Cancer cells could not stop growing because of their oncogene mutations. They stayed active and absorbed more of the chemo.
The result: healthy cells were more resilient, while cancer cells became more vulnerable.

Clinical trials at USC, Leiden, and elsewhere have replicated parts of this finding in humans, showing reduced side effects and, in some studies, improved tumor response.³ The fasting-mimicking diet (FMD) is a structured 5-day low-calorie program (such as ProLon) designed to capture the benefits of fasting without total food restriction.¹

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How does Fishtown Medicine support cancer patients?

We act as a support team alongside your oncologist, not in place of them. Our role is to handle the metabolic and lifestyle layer.

Fasting and FMD timing. We help patients time a 48 to 72 hour fast, or a structured FMD like ProLon, around their infusion cycles, with full bloodwork monitoring.
Targeted nutrition. For certain cancers (most notably glioblastoma), shifting the body to run on ketones may starve glucose-dependent tumors. For most other cancers, we focus on lower-glycemic eating, adequate protein, and reducing inflammation.
Exercise as therapy. Exercise is one of the strongest "drugs" we have during cancer treatment. It increases blood flow to the tumor (which can improve drug delivery), boosts natural killer cell activity, reduces fatigue, and protects muscle mass during chemotherapy.
Sleep optimization. Quality sleep supports immune function, mood, and treatment tolerance. We work on circadian alignment, melatonin timing, and managing chemo-related insomnia.
Stress and mental health. A regular mindfulness practice and access to support are not optional during cancer treatment. We help connect patients to counseling and survivor groups.

What supplements and repurposed drugs are evidence-based?

We use specific tools to address growth pathways, always coordinated with the oncology team to avoid drug interactions.

Evidence-Based Treatment

Dr. Ash reviews the research - and applies it to your specific biology.

Book a Consultation

Agent	Mechanism	Evidence base
Metformin	Lowers glucose and insulin/IGF-1 signaling.	Large observational data in diabetics shows lower cancer incidence and mortality. Active randomized trials in several cancers.⁴
Melatonin (high dose)	Anti-angiogenic, immune-supporting, sleep aid.	Meta-analyses suggest improved survival and quality of life in some solid tumors when added to standard care.⁵
Berberine	AMPK activator (similar pathway to metformin).	Lab and small clinical data show metabolic benefits and lower glucose uptake in tumor cells.
High-dose IV vitamin C	Acts as a pro-oxidant at high concentrations.	Trials in pancreatic, ovarian, and other cancers show reduced toxicity from chemo and possible synergy. Timing matters.
Omega-3 (EPA/DHA)	Reduces cachexia (cancer-related muscle loss) and inflammation.	Multiple randomized trials show muscle preservation during chemotherapy.

Guidance from the clinic

"You are not a helpless passenger. You are the co-pilot."

I have your back: At Fishtown Medicine, the goal is not just to order tests and hand you a result. We interpret, explain, and advocate. You should feel like you have a Chief Medical Officer in your corner, fighting for clarity and access, not just checkboxes.

A common patient question: "Dr. Ash, my oncologist said diet does not matter." My response: "Your oncologist is excellent at targeting tumors. My job is making sure your body is in the best possible shape to handle the treatment and recover." Large institutions are slower to adopt nutritional and metabolic science because it does not fit a clean clinical trial pipeline. But the data on insulin and IGF-1 driving cancer growth is real and growing. We do not fight the oncologist. We complement their tools by making your body a more hostile environment for the tumor and a more resilient one for you.

Actionable steps for Philadelphians

Build your team.

Get an integrative partner. You need someone to monitor your labs (albumin, glucose, lymphocyte counts, vitamin D, ferritin) during treatment. We do this for our cancer patients in close coordination with their oncology team at Penn, Jefferson, Fox Chase, or other centers.
Move every day. A 20-minute walk during chemo cycles reduces fatigue and protects muscle. Local survivor fitness groups like "We Can Row Philly" make consistency easier.
Protect sleep. 7 to 9 hours, with melatonin if your oncology team approves. Sleep is when most repair and immune work happens.
Eat for muscle preservation. 1.0 to 1.2 grams of protein per pound of target body weight per day. Cachexia (cancer-related muscle loss) is a major driver of poor outcomes.

Starve what hurts you. Feed what heals you. Book your Warm Invitation Call

Scientific References

Vernieri C, Longo VD, et al. Cyclic Fasting-Mimicking Diet in Cancer Treatment: Preclinical and Clinical Evidence. Cell Metab. 2024.
Nencioni A, Caffa I, Cortellino S, Longo VD. Fasting and cancer: molecular mechanisms and clinical application. Nat Rev Cancer. 2018;18(11):707-719.
Safdie FM, et al. Fasting and cancer treatment in humans: A case series report. Aging (Albany NY). 2009;1(12):988-1007.
Christofides A, et al. The role of metformin in the management of patients with cancer. Curr Pharm Des. 2018;24(5):665-677.
Cao Y, et al. Light at night, melatonin and cancer risk: a systematic review and meta-analysis. Eur J Cancer Prev. 2019.

Fishtown Medicine | Treatments

2418 E York St, Philadelphia, PA 19125(267) 360-7927 hello@fishtownmedicine.comHSA/FSA Eligible

Frequently Asked Questions

Common Questions

Fasting during cancer treatment can be safe and may be beneficial, but only under medical supervision and only for the right patients. If you are cachectic (already losing weight unintentionally) or underweight, fasting is dangerous. For patients who are overweight or normal weight with strong nutritional reserves, supervised fasting around chemo cycles can reduce side effects and may improve treatment response. Always coordinate with your oncologist.

No, you should not avoid all carbohydrates during cancer treatment unless you are under specific guidance for a ketogenic protocol (most often used in glioblastoma). Most patients do best with a Mediterranean-style approach: lower-glycemic carbs (vegetables, legumes, berries, whole grains) plus adequate protein and healthy fats. Drastic carb restriction without medical supervision can drive weight loss and worsen muscle wasting.

Yes, exercise is safe and beneficial during chemotherapy for most patients. Multiple large studies and the American College of Sports Medicine guidelines confirm that regular movement during treatment reduces fatigue, depression, anxiety, and treatment-related muscle loss. The intensity and type should be tailored to your blood counts (especially platelets and hemoglobin) and your treatment cycle, but doing nothing is rarely the right answer.

Integrative care will not interfere with chemotherapy if it is coordinated with your oncology team. The risk shows up when patients take supplements, antioxidants, or "natural" therapies without telling their oncologist. Some antioxidants (high-dose vitamin E, NAC, certain mushroom extracts) can theoretically blunt the oxidative effects of certain chemotherapies. We always check the timing and the specific regimen.

Cachexia is cancer-related muscle and weight loss, and it is one of the strongest predictors of poor cancer outcomes. Up to 80% of advanced cancer patients develop some degree of cachexia, and it is responsible for a significant portion of cancer deaths. Preventing it requires a high protein intake (1.0 to 1.2 grams per pound), resistance training, and addressing inflammation. Once cachexia takes hold, it is much harder to reverse.

Deep-Dive Questions

The Warburg effect is the observation that cancer cells preferentially use glucose for energy through fermentation (glycolysis) rather than the more efficient mitochondrial oxidative phosphorylation, even when oxygen is available. This metabolic shift is now considered a hallmark of cancer. It is why PET scans (which use radioactive glucose) light up tumors, and it is the conceptual basis for ketogenic and metabolic therapy approaches in oncology.

IGF-1 (insulin-like growth factor 1) is a hormone that drives cell proliferation and inhibits apoptosis (programmed cell death). High IGF-1 levels are linked to higher rates of breast, prostate, and colon cancers. Insulin and IGF-1 share many signaling pathways, which is part of why poor metabolic health is associated with worse cancer outcomes. Lowering IGF-1 (through fasting, lower protein at certain phases, and exercise) is one of the few accessible levers in this pathway.

The fasting-mimicking diet (FMD), developed by Valter Longo, is a structured 5-day low-calorie, plant-based, low-protein eating protocol that puts the body into a fasting-like state without total food restriction. The most studied version is ProLon. The advantage over a true water fast is better tolerability, lower risk of muscle loss, and easier coordination with cancer treatment. Most clinical trial data on fasting in oncology is from FMD, not pure water fasting.

The ketogenic diet has the strongest evidence in glioblastoma (a type of brain cancer), where small trials show possible benefit when combined with standard treatment. Evidence is more mixed for other cancers. The risks include weight loss, muscle loss, and lipid changes, so a "ketogenic for cancer" plan should be supervised by clinicians familiar with both oncology and metabolic medicine. It is not a fit for every cancer or every patient.

Metformin is a diabetes drug that has gained significant attention in oncology for its potential anti-cancer effects through AMPK activation, lower insulin/IGF-1, and direct effects on cancer cell metabolism. Several randomized trials are ongoing in breast, colon, and prostate cancers. We sometimes use it off-label as an adjunct in patients with elevated insulin or pre-diabetes, with full informed consent and in coordination with the oncologist.

Exercise is sometimes called "chemotherapy" in functional medicine circles because it has measurable, drug-like effects on cancer biology. It boosts natural killer cells, improves blood flow to tumors (which can enhance chemo delivery), reduces inflammation, lowers insulin and IGF-1, and preserves muscle. Multiple large epidemiologic studies show that exercise during and after cancer treatment reduces recurrence and mortality, often by 25% to 40%.

Some medicinal mushroom extracts have moderate evidence as immune modulators in cancer. Turkey tail (PSK/Krestin) is approved as a cancer adjunct in Japan with decades of clinical use, especially in colorectal and gastric cancers. Reishi, lion's mane, and maitake have less robust data but show immune-supporting effects in lab and animal studies. Quality varies enormously between products, so source matters.

Differential stress resistance is the principle that healthy cells and cancer cells respond differently to a stressor like fasting. Healthy cells, when starved, drop into a protective shield mode and pause growth. Cancer cells, locked into growth by their mutations, cannot pause; they remain vulnerable. Pairing fasting with chemo on the right schedule may protect normal tissue while concentrating chemos effect on the tumor.

You can usually tell with one direct, respectful conversation. Bring a short list of what you are doing or considering (a fast around chemo cycles, melatonin, vitamin D, exercise, diet) and ask their thoughts. Many oncologists are open to integrative care when it is coordinated and evidence-based. If yours is dismissive of every lifestyle factor, that is a clue to find a co-managing physician (which is part of what we do at Fishtown).

Vitamin D plays a meaningful role in cancer outcomes, especially in colorectal, breast, and prostate cancers. Low vitamin D at diagnosis is associated with worse survival in multiple cancer types. Whether supplementation improves outcomes is still debated, but the safety, low cost, and broader benefits make it a reasonable target. We aim for serum 25-OH vitamin D levels in the 40 to 60 ng/mL range during treatment.

Antioxidants during chemo or radiation are nuanced. Some chemotherapies and radiation work by generating oxidative stress in cancer cells, so high-dose antioxidants taken at the same time could theoretically reduce treatment effectiveness. Other phases of treatment may benefit from antioxidant support to reduce damage to healthy tissue. The simple rule: time antioxidants away from active treatment days, and always coordinate with your oncology team.

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