Antioxidants, Polyphenols, and Cancer Therapies

There’s often confusion about how antioxidants or polyphenols might interact with cancer treatments like immunotherapy, chemotherapy, or pro-oxidant therapies (IV Vitamin C, HBOT, Artemisinin, Methylene Blue + light). The scientific literature suggests that timing can influence how these compounds behave in the body.

✅ Immunotherapy (e.g. Keytruda, Opdivo)

These drugs reactivate T-cells, which use bursts of reactive oxygen species (ROS) to attack tumors.

Some studies suggest that very strong antioxidants (Vitamin C, NAC, glutathione, Vitamin E) could, if taken right at infusion, reduce this ROS signal.

Polyphenols (curcumin, EGCG, resveratrol, quercetin) act differently. They don’t just “scavenge ROS” but instead modulate pathways like NF-κB and STAT3. Literature suggests they may even support immune function during checkpoint inhibitor therapy.

✅ Chemotherapy (platinums, taxanes, anthracyclines, etc.)

Many chemotherapies kill cancer cells through oxidative stress.

Strong antioxidants given at the same time could theoretically reduce this effect, which is why some protocols separate them by a day or two.

Polyphenols are more nuanced: some studies show they can reduce side effects and may even increase cancer sensitivity to chemo, but timing still appears to matter.

✅ Pro-oxidant Therapies (IV Vitamin C, HBOT, Artemisinin, CDS, Methylene Blue + light)

These therapies aim to increase ROS stress in cancer cells.

Combining them with strong antioxidants in the same window may cancel out the intended effect.

Polyphenols don’t appear to block this process and in some contexts have been reported to enhance it.

✅ Key Idea

Classical antioxidants (Vitamin C, NAC, glutathione, ALA, Vitamin E) directly scavenge ROS, which can interfere with therapies that rely on oxidative stress if taken at the same time.

Polyphenols (curcumin, EGCG, resveratrol, quercetin) act more like signaling regulators and are generally reported as supportive rather than disruptive.

The main consideration is not “whether” but when these compounds are used alongside treatment.

👉 This is still a grey area. Some integrative oncologists pause polyphenols on treatment days (to be ultra cautious), others keep them in.

How do you handle it?

⚠️ Disclaimer: This post is a summary of published research and is for educational purposes only. It is not medical advice. Everyone’s situation is different, and decisions about supplements or timing with treatments should always be discussed with a qualified healthcare provider.

✅ References

1. Yeung, A. W. et al. “Polyphenols in cancer treatment: ROS signaling, immune modulation, and checkpoint inhibitors.” Cancers (2021).

2. Simone, C. B. et al. “Antioxidants and other nutrients do not interfere with chemotherapy or radiation therapy and can increase survival.” CA: A Cancer Journal for Clinicians (2007).

3. Llopiz, D. et al. “Enhancement of anti-PD-1 therapy efficacy by resveratrol in preclinical cancer models.” OncoImmunology (2020).

4. Prasad, K. N. et al. “Antioxidants and chemotherapy: Is there a rationale for concurrent use?” Journal of the American College of Nutrition (2016).

5. Gonzalez, M. J. et al. “High-dose vitamin C and cancer therapy: Timing matters.” Integrative Cancer Therapies (2018).

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